Engine Mechanical - 8.1l v8 Chevrolet Avalanche I

MODEL IDENTIFICATION

MODEL IDENTIFICATION

ENGINE IDENTIFICATION

Engine is identified by eighth character of Vehicle Identification Number (VIN). VIN is stamped on a metal plate on top left end of instrument panel, near windshield.

VALVE CLEARANCE ADJUSTMENT

Engine is equipped with hydraulic valve lifters. No adjustments are required.

TROUBLE SHOOTING

Note. To trouble shoot engine mechanical components, see ENGINE MECHANICAL in BASIC TROUBLE SHOOTING article in GENERAL INFORMATION.

REMOVAL & INSTALLATION

Note. For repair procedures not covered in this article, see ENGINE OVERHAUL PROCEDURES article in GENERAL INFORMATION.

Note. For reassembly reference, label all electrical connectors, vacuum hoses and fuel lines before removal. Also place mating marks on engine hood and other major assemblies before removal.

FUEL PRESSURE RELEASE

Fuel Pressure Release Procedure

1. Disconnect negative battery cable.
2. Remove fuel injector sight shield.
3. Loosen fuel filler cap in order to relieve fuel tank vapor pressure.
4. Connect Fuel Pressure Gauge (J-34730-1A) to fuel pressure valve. Wrap a shop towel around the fitting while connecting gauge in order to avoid spillage.
5. Install gauge bleed hose into an approved container.
6. Open valve on the gauge to bleed system pressure. The fuel connections are now safe for servicing.
7. Drain any fuel remaining in the fuel pressure gauge into an approved container.

Removal (Metal Collar)

1. Relieve fuel system pressure before servicing any fuel system connection. See «FUEL PRESSURE RELEASE»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__fuel-pressure-release) .
2. Remove retainer from quick-connect fitting.
3. Blow dirt out of the fitting using compressed air.
4. Choose the correct tool from the Fuel Line Disconnect Tool Set (J-37088-A) for the size of the fitting. Insert tool into the female connector, then push inward in order to release the locking tabs.
5. Pull the connection apart.
6. Use a clean shop towel in order to wipe off the male pipe end.
7. Inspect both ends of the fitting for dirt and burrs. Clean or replace the components as required.

Installation (Metal Collar)

1. Apply a few drops of clean engine oil to male fuel pipe end.
2. Push both sides of quick-connect fitting together in order to cause the retaining tabs to snap into place.
3. Once installed, pull on both sides of the quick-connect fitting to ensure connection is secure.

Removal (Plastic Collar)

1. Relieve fuel system pressure before servicing any fuel system connection. See «FUEL PRESSURE RELEASE»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__fuel-pressure-release) .
2. Using compressed air, blow any dirt out of the quick-connect fitting.
3. Squeeze the plastic retainer release tabs. Pull the connection apart.

Installation (Plastic Collar)

1. Apply a few drops of clean engine oil to male fuel pipe end.
2. Push both sides of quick-connect fitting together in order to cause the retaining tabs to snap into place.
3. Once installed, pull on both sides of the quick-connect fitting in order to make sure the connection is secure.

COOLING SYSTEM BLEEDING

Note. When adding coolant, use DEX-COOL® coolant. If silicated coolant is added to system, premature engine, heater core or radiator corrosion may result. In addition, engine coolant will require change sooner, at 30,000 miles or 24 months.

Refilling & Bleeding Procedure

1. Close radiator drain cock.
2. Fill system through the surge tank opening.
3. Pre-mix a 50 to 60 percent solution of DEX-COOL® and clean, drinkable water.
4. Slowly add the pre-mixed solution to the surge tank until the level is slightly above the COLD FILL mark.
5. Start and operate engine at idle for one minute.
6. Loosely install surge tank cap. DO NOT allow system to build up pressure.
7. Cycle engine from idle to 3000 RPM in 30-second intervals until engine coolant temperature reaches 210°F (99°C) and the thermostat opens.
8. Turn off engine.
9. Remove surge tank fill cap. To remove, slowly rotate the cap counterclockwise. Stop rotating and allow hissing to stop. After all hissing stops, continue turning counterclockwise in order to remove the fill cap.
10. Start and operate engine for one minute. Fill the surge tank to 1/2" (12.7 mm) above the COLD FILL mark on the surge tank.
11. Install radiator surge tank cap.
12. Cycle engine from idle to 3000 RPM in 30-second intervals until engine coolant temperature reaches 210°F (99°C) and thermostat opens.
13. Turn off engine.
14. Top off coolant, as necessary, to 1/2" (12.7 mm) above the COLD FILL mark on the surge tank.
15. Rinse away any excess coolant from engine and engine compartment. Inspect coolant concentration.

Removal

1. Raise and support vehicle.
2. Remove oil pan skid plate bolts and plate, if necessary.
3. Support transmission with a transmission jack.
4. Remove transmission mount-to-transmission support nuts.
5. Raise transmission off of the transmission support.
6. Remove transmission support crossmember bolts.
7. Remove transmission support crossmember.
8. Remove muffler. See «MUFFLER REPLACEMENT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
9. Remove clip around engine harness and oxygen sensor pigtail.
10. Disconnect the Connector Position Assurance (CPA) retainer.
11. Disconnect oxygen sensor electrical connector.
12. Remove oxygen sensor.
13. Remove exhaust manifold pipe.
14. Slide exhaust manifold pipe hanger out of the exhaust pipe hanger bracket.
15. Discard exhaust manifold pipe seal.

Installation

1. Install NEW exhaust manifold pipe seal to the manifold pipe.
2. Install exhaust manifold pipe.
3. Apply lubricant to exhaust pipe hanger bracket to aid in installation.
4. Slide exhaust manifold pipe hanger into exhaust pipe hanger bracket.
5. Install and tighten exhaust manifold pipe nuts. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
6. If exhaust manifold pipe was replaced, apply Anti-Seize Compound GM (PN 12377953) to threads of old oxygen sensor. Install oxygen sensor. Tighten oxygen sensor to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
7. If exhaust manifold pipe was not replaced, connect oxygen sensor electrical connector. Connect CPA retainer. Install clip around engine harness and oxygen sensor pigtail.
8. Install muffler. See «MUFFLER REPLACEMENT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
9. Install transmission support crossmember.
10. Install transmission support crossmember bolts. Tighten transmission support crossmember bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
11. Lower transmission onto transmission support.
12. Install transmission mount to transmission support nuts. Tighten transmission mount nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
13. Remove transmission jack.
14. Install oil pan skid plate and bolts, if necessary. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
15. Lower vehicle.

1. On 2WD models, raise vehicle to a height to work through the front wheelhouse opening.
2. On 4WD models, raise vehicle and remove front wheels.
3. On all models, remove the left or right front wheel.
4. Remove wheelhouse inner panel push pin retainers.
5. Remove wheelhouse inner panel.
6. Working through the wheelhouse opening, remove engine mount heat shield bolts.
7. Remove engine mount heat shield.
8. Remove engine mount-to-engine mount bracket bolt.
9. Remove oil pan skid plate bolts and plate (if equipped).
10. Remove engine shield bolts and shield.
11. Raise engine with a suitable jack in order to remove the engine mount and bracket.
12. Remove engine mount-to-engine bolts.
13. Remove engine mount.
14. Remove engine mount bracket through-bolts.
15. Remove engine mount bracket.

1. Install engine mount bracket onto the frame.
2. Loosely install the engine mount bracket through-bolts.
3. Position engine mount to engine.
4. Loosely install engine mount-to-engine bolts.
5. Tighten engine mount bracket through-bolts and engine mount-to-engine bolts. Tighten the engine mount bracket through bolts to specification. Tighten engine mount-to-engine bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
6. Install engine shield and bolts. Tighten engine shield bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
7. Lower engine.
8. Install oil pan skid plate and bolts (if equipped). Tighten oil pan skid plate bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
9. Install engine mount heat shield.
10. Install engine mount-to-engine mount bracket bolts. Tighten engine mount-to-engine mount bracket bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
11. Install wheelhouse inner panel.
12. Install wheelhouse inner panel push pin retainers.
13. Install left front tire and wheel.
14. Lower vehicle.

1. Raise hood to service position. Remove the hood hinge bolts. Raise hood until vertical. Install hood hinge bolts until snug in the service position.
2. Loosen clamps at throttle body and air cleaner.
3. Remove air cleaner outlet duct.
4. Disconnect battery terminal cables.
5. Remove ignition coils.
6. Relieve fuel system pressure. See «FUEL PRESSURE RELEASE»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__fuel-pressure-release) .
7. Disconnect fuel feed and return pipes from the fuel rail. See «QUICK CONNECT FITTING SERVICE»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__fuel-pressure-release) .
8. Remove A/C compressor.
9. Remove radiator.
10. Disconnect Throttle Actuator Control (TAC) module electrical connector.
11. Remove vacuum lines from engine, as required.
12. Remove EGR valve adapter.
13. Remove ground cable bolt at the engine block.
14. Remove generator.
15. Remove engine electrical harness and tie out of the way.
16. Raise and suitably support the vehicle with safety stands.
17. Remove starter motor.
18. Remove hoses from the power steering pump.
19. Remove exhaust manifold pipe. See «EXHAUST MANIFOLD PIPE»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
20. Remove catalytic converter. See «CATALYTIC CONVERTER»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
21. Remove torque converter bolts.
22. Remove bolts from the transmission to engine.
23. Remove engine oil cooler lines from engine block.
24. Attach Engine Lift Brackets (J-36857) to rear of right cylinder head and to front of the left cylinder head.
25. Install attaching bolt and washer. Tighten lift bracket bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
26. Remove engine mount heat shield bolts and shields.
27. Remove engine mount to engine mount bracket bolts.
28. Remove engine using a suitable lifting devise.
29. Install engine onto a suitable engine stand.
30. Remove generator mounting bracket.
31. Remove A/C compressor/power steering pump bracket from cylinder head.
32. Remove lift brackets from cylinder head.

1. Attach engine lift brackets to rear of the right cylinder head and to the front of the left cylinder head.
2. Install attaching bolt and washer. Tighten lift bracket bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
3. Install A/C compressor/power steering mounting bracket to the engine block. Tighten the power steering pump bracket bolts and nut to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
4. Install generator bracket.
5. Remove engine using a suitable lifting devise.
6. Install engine into vehicle.
7. Install engine mount-to-engine mount bracket bolts.
8. Install engine mount heat shield and bolts.
9. Remove engine lift hooks from the cylinder heads.
10. Raise vehicle and support with safety stands.
11. Install engine oil cooler lines to engine block.
12. Install bolts from transmission to engine.
13. Install torque converter bolts.
14. Install catalytic converter. See «CATALYTIC CONVERTER»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
15. Install exhaust manifold pipe. See «EXHAUST MANIFOLD PIPE»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
16. Install hoses to power steering pump.
17. Install starter motor.
18. Lower vehicle.
19. Route engine electrical harness.
20. Install generator.
21. Install ground cable bolt at engine block. Tighten engine wiring harness bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
22. Install EGR valve adapter.
23. Install vacuum lines to engine.
24. Connect TAC module electrical connector.
25. Install radiator.
26. Install A/C compressor.
27. Disconnect fuel feed and return pipes from the fuel rail.
28. Install ignition coils.
29. Connect battery cables.
30. Install air cleaner outlet duct.
31. Tighten clamps at throttle body and air cleaner.
32. Remove hood hinge bolts from the service position.
33. Lower hood to normal position.
34. Install the hood hinge bolts. Tighten the hood hinge bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
35. Before starting a new engine or one that has been repaired, complete the following procedure. Fill engine with the proper quantity and grade of oil. Add Engine Oil Supplement GM (PN 1052367) to engine oil. Remove fuel pump fuse and disconnect the coil harness connectors, then crank engine until oil pressure is present. Crank engine several times. Listen for any unusual noises or evidence that any of the parts are binding. Install fuel pump fuse and connect the coil harness connectors. Start engine and listen for unusual noises. Check oil pressure gauge or light and confirm that engine has acceptable oil pressure. If necessary, install an oil pressure gauge and measure oil pressure. Operate engine at about 1000 RPM until engine has reached normal operating temperature. Inspect for oil and or coolant leaks while engine is running. Turn off engine and perform a final inspection for proper engine oil and coolant levels. The final step is to perform the Crankshaft Position (CKP) sensor variation learn procedure. See CRANKSHAFT POSITION SENSOR under PROGRAMMING in SELF-DIAGNOSTICS - 8.1L "C" & "K" SERIES article.

INTAKE MANIFOLD

Note. The intake manifold, throttle body, fuel rail, and injectors may be removed as an assembly. If not servicing the individual components, remove manifold as a complete assembly. (Scheme 1)

1. Loosen clamps at the throttle body and air cleaner.
2. Remove air cleaner outlet duct.
3. Loosen intake manifold sight shield bolt.
4. Remove sight shield from bracket.
5. Remove sight shield from bracket and nuts.
6. Relieve fuel system pressure. See «FUEL PRESSURE RELEASE»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__fuel-pressure-release).
7. Disconnect fuel feed and return lines. See «QUICK CONNECT FITTING SERVICE»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__fuel-pressure-release).
8. Disconnect engine harness clips from the studs on the front of dash.
9. Disconnect engine harness clip from the wheelhouse splash panel.
10. Disconnect the pressure cycling switch, surge tank switch, and Mass Airflow (MAF) sensor harness connectors. (Scheme 2)
11. Reposition engine harness branch to top of engine.
12. Remove the Connector Position Assurance (CPA) retainer at the ignition coil harness.
13. Disconnect the Manifold Absolute Pressure (MAP) sensor, ignition coil harness, and Engine Coolant Temperature (ECT) sensor connectors. (Scheme 3)
14. Remove engine harness bolt and studs.
15. Remove the CPA retainer at the ignition coil harness.
16. Disconnect the generator, injector harness, ignition coil harness, Throttle Position (TP) sensor, Electronic Throttle Control (ETC), and purge valve solenoid connectors. (Scheme 4)
17. Reposition engine harness to drivers-side of engine compartment.
18. Remove bypass valve vacuum hose from the intake manifold.
19. Disconnect EGR valve harness connector. (Scheme 5)
20. Remove EGR pipe bolts at EGR adapter.
21. Reposition EGR pipe.
22. Remove and discard EGR valve pipe gasket.
23. Remove fuel pressure regulator vacuum hose.
24. Remove fuel rail studs, and fuel rail. (Scheme 6)
25. Remove intake manifold bolts, and remove intake manifold. (Scheme 7)
26. Remove and discard intake manifold side gaskets.
27. Remove and discard intake manifold end seals.
28. Remove splash shield.
29. If replacing intake manifold, see «INTAKE MANIFOLD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) under OVERHAUL.
30. Clean and inspect intake manifold. See «INTAKE MANIFOLD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) under OVERHAUL.

1. If replacing intake manifold, see «INTAKE MANIFOLD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) under OVERHAUL.
2. Install splash shield.
3. Ensure splash shield snap fits between the cylinder heads.
4. Install NEW intake manifold end seals.
5. Install NEW intake manifold side gaskets onto the cylinder heads.
6. Ensure intake manifold gasket tabs align with the hole in the head gasket.
7. Ensure intake manifold gasket tabs align with the slot in the intake manifold end seals.
8. Install intake manifold gaskets to the cylinder head with "THIS SIDE UP" stamp facing up.
9. Install intake manifold. (Scheme 7)
10. Apply Threadlock (12345382) to a minimum of 8 threads of intake manifold bolts.
11. Install intake manifold bolts. (Scheme 7)
12. Tighten intake manifold bolts in sequence shown, using 4 passes. Tighten intake manifold bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
13. Install fuel rail. (Scheme 6)
14. Install fuel rail studs. Tighten fuel rail studs to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
15. Install fuel pressure regulator vacuum hose.
16. Install EGR valve pipe gasket.
17. Position EGR pipe.
18. Install EGR pipe bolts at EGR adapter. Tighten EGR pipe bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
19. Connect EGR valve harness connector. (Scheme 5)
20. Install the bypass valve vacuum hose to the intake manifold.
21. Position engine harness over engine compartment.
22. Connect the generator, injector harness, ignition coil harness, TP sensor & ECT sensor, and purge valve solenoid harness connector. (Scheme 4)
23. Install the CPA retainer at the ignition coil harness.
24. Install engine harness bolt and studs. Tighten engine harness bolt to specification. Tighten engine harness studs to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
25. Connect MAP sensor, ignition coil harness and ECT sensor harness connector. (Scheme 3)
26. Position engine harness branch over the top of the engine.
27. Connect the pressure cycling switch, surge tank switch, and MAF sensor connector. (Scheme 2)
28. Connect engine harness clip to wheelhouse splash shield.
29. Connect engine harness clips to studs on front of dash.
30. Connect fuel feed and return pipes.
31. Install engine sight shield bracket and nuts. Tighten sight shield bracket nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
32. Install sight shield to bracket.
33. Tighten intake manifold sight shield bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
34. Install air cleaner outlet duct.
35. Tighten clamps at throttle body and air cleaner. Tighten air cleaner outlet duct clamp to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).

Scheme 1

Scheme 2

Scheme 3

Scheme 4

Scheme 5

Scheme 6

Scheme 7

1. Remove wheelhouse panel.
2. Remove oil level indicator tube, if removing right exhaust manifold.
3. If removing left or right side exhaust manifold, remove spark plug wires from spark plugs and ignition coil. Remove spark plugs.
4. If removing right exhaust manifold, remove Exhaust Gas Recirculation (EGR) pipe nuts from exhaust manifold. Remove EGR pipe bracket bolt. Remove and discard EGR pipe gasket. Reposition EGR pipe.
5. If removing left or right side exhaust manifold, raise and support vehicle.
6. Remove appropriate exhaust manifold heat shield bolts and nuts, remove exhaust manifold heat shield.
7. Lower vehicle.
8. Remove exhaust manifold bolt and nuts, remove exhaust manifold.
9. Remove and discard exhaust manifold gasket.
10. If reusing exhaust manifold, clean and inspect exhaust manifold.

1. Install a NEW exhaust manifold gasket and manifold.
2. Install exhaust manifold bolt and nuts. Tighten the bolt to specification. Tighten the nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
3. Raise vehicle.
4. Install exhaust manifold heat shield. Tighten bolts and nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
5. Lower vehicle.
6. If installing right exhaust manifold, position the EGR.
7. Install a NEW EGR pipe gasket.
8. Install EGR pipe bracket bolt. Tighten the bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
9. Install EGR pipe nuts to the exhaust manifold. Tighten nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
10. If installing left or right side exhaust manifold, install spark plugs.
11. Install spark plug wires to spark plugs and ignition coils.
12. Install oil level indicator tube, if removed (right side exhaust manifold).
13. Install wheelhouse panel.

1. Drain cooling system.
2. Remove intake manifold. See «INTAKE MANIFOLD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__intake-manifold) .
3. Remove valve rocker arms and push rods. See «VALVE ROCKER ARM & PUSH ROD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
4. Remove engine harness ground bolts.
5. Reposition engine harness grounds and ground strap from cylinder head.
6. Remove water crossover.
7. Remove exhaust manifold. See «EXHAUST MANIFOLD (LEFT & RIGHT SIDE)»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
8. Remove and discard cylinder head bolts.
9. Remove cylinder head.
10. Remove and discard cylinder head gasket.
11. Clean and inspect cylinder head. See «CYLINDER HEAD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) under OVERHAUL.

Note. Ensure threaded holes in engine block are clean and not damaged. Do not use sealer on any engines that use a composition type gasket. Align cylinder head gasket locating marks to face up. Ensure that head gasket tabs are located over cylinders No. 1 and 2 for correct installation.

1. Place a NEW cylinder head gasket into position.
2. Install cylinder head.
3. If not pre-applied to the NEW cylinder head bolts, apply Sealant (12346004) to cylinder head bolts.
4. Install cylinder head bolts No. 1, 2 and 3. (Scheme 8)
5. Tighten cylinder head bolts. Tighten cylinder head bolts a first pass, in sequence to specification. (Scheme 9)and «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications). Tighten cylinder head bolts a second pass, in sequence to specification, then an additional 120 degrees using a Torque Angle Meter ((J-36660-A). Tighten bolts (1, 2, 3, 6, 7, 8, 9, 10, 11, 14, 16 & 17) an additional 60 degrees, bolts (15 & 18) an additional 45 degrees, and bolts (4, 5, 12 & 13) an additional 30 degrees a final pass in sequence using the torque angle meter.
6. Install exhaust manifold. See «EXHAUST MANIFOLD (LEFT & RIGHT SIDE)»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
7. Install water crossover.
8. Position engine harness grounds and ground strap to cylinder head.
9. Install engine harness ground bolts. Tighten engine harness ground bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
10. Install valve rocker arms and push rods. See «VALVE ROCKER ARM & PUSH ROD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
11. Install intake manifold. See «INTAKE MANIFOLD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__intake-manifold).
12. Fill and bleed cooling system. See «COOLING SYSTEM BLEEDING»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__cooling-system-bleeding).

Scheme 8

Scheme 9

1. Drain cooling system.
2. Remove intake manifold. See «INTAKE MANIFOLD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__intake-manifold) .
3. Remove valve rocker arms and pushrod's. See «VALVE ROCKER ARM & PUSH ROD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
4. Remove Engine Coolant Temperature (ECT) sensor clip from bracket.
5. Remove ECT sensor from cylinder head.
6. Remove ECT sensor bracket bolt and bracket.
7. Remove heater inlet and outlet hoses from hose bracket.
8. Remove heater hose bracket bolts and bracket from cylinder head.
9. Remove water crossover.
10. Remove exhaust manifold. See «EXHAUST MANIFOLD (LEFT & RIGHT SIDE)»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
11. Remove and discard cylinder head bolts.
12. Remove cylinder head.
13. Remove and discard cylinder head gasket.
14. Clean and inspect cylinder head. See «CYLINDER HEAD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) under OVERHAUL.

Note. Do not reuse a cylinder head gasket once the initial clamping loads are applied. The initial tightening sequence procedure of the cylinder head bolts compresses the cylinder head gasket. If any bolt must be loosened once the initial sequence is started, cylinder head gasket must be replaced. Failure to replace cylinder head gasket can lead to cylinder head bolt breakage or cylinder head gasket failure. A broken cylinder head bolt or failed cylinder head gasket can lead to extensive engine damage.

Note. Ensure threaded holes in engine block are clean and not damaged. Do not use sealer on any engines that use a composition type gasket. Align cylinder head gasket locating mark to face up. Ensure that head gasket tabs are located over cylinders No. 1 and 2 for correct installation.

1. Place NEW cylinder head gasket into position.
2. Install cylinder head.
3. If not pre-applied to the new cylinder heads bolts, apply Sealant (12346004) to cylinder head bolts.
4. Install cylinder head bolts No. 1, 2 and 3. (Scheme 10)
5. Tighten cylinder head bolts a first pass, in sequence to specification. Tighten the cylinder head bolts a second pass, in sequence to specification. (Scheme 9)and «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications), plus an additional 120 degrees using the Torque Angle Meter (J-36660-A). Tighten bolts (1, 2, 3, 6, 7, 8, 9, 10, 11, 14, 16 & 17) an additional 60 degrees, bolts (15 & 18) an additional 45 degrees, and bolts (4, 5, 12 & 13) an additional 30 degrees a final pass using the torque angle meter.
6. Install exhaust manifold. See «EXHAUST MANIFOLD (LEFT & RIGHT SIDE)»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
7. Install water crossover.
8. Install heater hose bracket and bolts to cylinder head. Tighten heater hose bracket bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
9. Install heater inlet and outlet hoses to hose bracket.
10. Install ECT sensor bracket and bolt. Tighten ECT sensor bracket bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
11. Apply Sealant GN (PN 12346004) to threads of the ECT sensor.
12. Install ECT sensor to cylinder head. Tighten ECT sensor to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
13. Install ECT sensor clip to bracket.
14. Install valve rocker arms and push rods. See «VALVE ROCKER ARM & PUSH ROD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
15. Install intake manifold. See «INTAKE MANIFOLD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__intake-manifold).
16. Fill and bleed cooling system. See «COOLING SYSTEM BLEEDING»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__cooling-system-bleeding).

Scheme 10

1. Remove water pump. See «WATER PUMP»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
2. Remove crankshaft balancer. See «CRANKSHAFT BALANCER»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
3. Disconnect Camshaft Position (CMP) sensor electrical connector.
4. Remove engine harness clips from battery cable channel.
5. Remove CMP sensor bolt and sensor. (Scheme 11)
6. Remove battery cable channel bolt.
7. Remove and reposition battery cable channel.
8. Remove engine front cover bolts. Remove engine front cover. (Scheme 12)
9. Remove engine front cover gasket.
10. Remove crankshaft front oil seal from front cover.

1. Install a NEW crankshaft front oil seal using Front Cover Oil Seal Installer (J-42851).
2. Lubricate sealing surface of the crankshaft front oil seal with clean engine oil.
3. Apply Sealant GM (PN 12346286) in 2 places on engine block where the front cover meets the oil pan.
4. Install engine front cover gasket into the front cover.
5. Install front cover and gasket. Hold front cover up to crankshaft. Lift front cover while sliding the cover over crankshaft. Slide front cover towards engine block while keeping cover raised. Lower cover down over the dowel pin, allowing the front cover to rest on the sealant.
6. Install engine front cover bolts (Scheme 12) Tighten cover bolts in sequence a first pass to specification. Tighten engine front cover bolts in sequence a final pass to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
7. Position battery cable channel into place.
8. Install battery cable channel bolt. Tighten battery cable channel bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
9. Inspect the CMP sensor O-ring for cuts, cracks, tears or damage. Replace as needed.
10. Apply a light film of clean engine oil to the CMP sensor O-ring.
11. Install CMP sensor. Install CMP sensor bolt. Tighten CMP sensor bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications). (Scheme 11)
12. Install engine harness clips to the battery cable channel.
13. Connect CMP sensor electrical connector.
14. Install crankshaft balancer. See «CRANKSHAFT BALANCER»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
15. Install water pump. See «WATER PUMP»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).

Scheme 11

Scheme 12

1. Remove engine front cover. See «ENGINE FRONT COVER»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
2. Align timing marks on camshaft and crankshaft sprockets.
3. Remove camshaft sprocket bolts.
4. Remove camshaft sprocket and timing chain.
5. Install Crankshaft Protector Button (J 42846) into the end of the crankshaft.
6. Remove crankshaft sprocket using a suitable 3-jaw puller.
7. Clean and inspect timing chain and sprockets. Inspect for worn teeth, damaged teeth, chipped teeth, uneven wear on one edge of teeth, worn valleys between sprocket teeth, and crankshaft sprocket keyway for wear.

1. Using Crankshaft Sprocket Installer (J-22102), install crankshaft sprocket. Align keyway of the crankshaft sprocket with crankshaft pin.
2. Remove crankshaft sprocket installer.
3. Rotate crankshaft until crankshaft sprocket alignment mark is in 12 o'clock position.
4. Install camshaft sprocket and timing chain.
5. Ensure that crankshaft sprocket is aligned at 12 o'clock position and camshaft sprocket is aligned at 6 o'clock position.
6. Install camshaft sprocket bolts. Tighten camshaft sprocket bolts a first pass to specification. Tighten camshaft sprocket bolts a final pass to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
7. Install engine front cover. See «ENGINE FRONT COVER»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .

1. Remove valve rocker arm cover.
2. Remove valve rocker arm nuts, valve rocker arm balls, and valve rocker arms.
3. Remove valve push rods.
4. Remove valve rocker arm studs and push rod guides.
5. Clean and inspect valve rocker arms and push rods. See «VALVES»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) under OVERHAUL.

1. Apply Sealant GM (PN 12346004) to valve rocker arm stud-to-cylinder head threads.
2. Install push rod guides and valve rocker arm studs. Tighten valve rocker arm studs to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
3. Install the valve push rods.
4. Coat valve rocker arm and valve rocker arm ball bearing surfaces with Lubricant GM (PN 12345501).
5. Install valve rocker arms, valve rocker arm balls, and valve rocker arm nuts. Tighten valve rocker arm nuts slowly to specification while guiding the tips of the rocker arms over the tips of the valves. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
6. Install valve rocker arm cover.

1. Remove valve rocker arms and push rods. See «VALVE ROCKER ARM & PUSH ROD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
2. Rotate crankshaft until both valves are closed before applying compressed air into cylinder.
3. Remove spark plug from cylinder being serviced.
4. Install Spark Plug Port Adapter (J-22794) into spark plug hole. Apply compressed air into cylinder in order to hold the valves closed. Lightly tap the valve spring cap to loosen the valve stem keys. Install Valve Spring Compressor (J-5892-D) to cylinder head. Install valve rocker arm nut. Using valve spring compressor, compress valve springs. (Scheme 13)
5. Remove valve stem keys.
6. Slowly release valve spring compressor.
7. Remove valve spring compressor from cylinder head.
8. Remove valve spring cap and valve spring from valve component housing. (Scheme 14)
9. Remove valve stem oil seal.

1. Lubricate valve stem and outside diameter of the valve guide seal with clean engine oil.
2. Lubricate rotators with clean engine oil.
3. Install valve stem oil seal over the valve tip and onto the valve guide using Valve Stem Seal Installer (J-43105). Tap valve stem seal onto valve guide until the valve stem seal installer fully seats the seal.
4. Install valve spring cap and spring into valve component housing. (Scheme 14)
5. Using valve spring compressor, compress valve spring.
6. Apply a small amount of clean grease to hold the valve stem keys in place. Carefully release the valve spring compressor. Ensure valve stem keys do not move. Remove valve spring compressor from the valve assembly. Release compressed air from cylinder being worked on. (Scheme 13)
7. Install spark plug.
8. Install valve rocker arms and push rods. See «VALVE ROCKER ARM & PUSH ROD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).

Scheme 13

Scheme 14

1. Remove intake manifold. See «INTAKE MANIFOLD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__intake-manifold) .
2. Remove valve rocker arms and push rods. See «VALVE ROCKER ARM & PUSH ROD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
3. Remove valve lifter guide retainer bolts and retainer.
4. Remove valve lifter guides.
5. Remove valve lifters.
6. Some valve lifters may be stuck in their bore due to gum or varnish deposits, These lifters can be removed using Valve Lifter Remover (J-3049-A).
7. Clean and inspect valve lifters. See «VALVES»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) under OVERHAUL.

Note. If a new camshaft is installed, replace all valve lifters.

1. Coat the valve lifter rollers with Lubricant (12345501).
2. Install valve lifters.
3. Install valve lifter guides over the flats on valve lifters, making sure rollers of the valve lifters are properly aligned with camshaft lobes.
4. Install valve lifter guide retainer.
5. Install valve lifter guide retainer bolts. Tighten valve lifter guide retainer bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
6. Install valve rocker arms and push rods. See «VALVE ROCKER ARM & PUSH ROD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) . Install intake manifold, see «INTAKE MANIFOLD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__intake-manifold) .

1. Remove grille.
2. Remove A/C condenser.
3. Remove valve lifters. See «VALVE LIFTER REPLACEMENT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
4. Remove timing chain and sprocket. See «TIMING CHAIN & SPROCKETS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
5. Remove camshaft retainer bolts and remove camshaft retainer.
6. Install three 8-1.25 x 100 mm bolts into camshaft front bolt holes. Using the bolts as a handle, carefully rotate and pull camshaft out of engine block. (Scheme 15)
7. Remove bolts from front of camshaft.
8. Clean and inspect camshaft. See «CAMSHAFT BEARING CLEANING & INSPECTION»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__camshaft-bearing-cleaning-inspection) under OVERHAUL.

1. Apply Lubricant (12345501) to camshaft lobes, camshaft bearing journals and camshaft bearings.
2. Install three 8-1.25 x 100 mm bolts into camshaft threaded bolt holes. Using bolts as a handle, carefully install camshaft. (Scheme 15)
3. Remove bolts from front of camshaft.
4. Install camshaft retainer and bolts. Tighten camshaft retainer bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
5. Install timing chain and sprocket. See «TIMING CHAIN & SPROCKETS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
6. Install valve lifters. See «VALVE LIFTER REPLACEMENT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8).
7. Install A/C condenser.
8. Install grille.

Scheme 15

1. Remove rear camshaft plug, if not previously removed. Insert a long bar through the front of engine and drive the plug out of rear bore.
2. Prior to bearing removal, inspect the camshaft bearings for loose fit in engine block bearing bores.
3. Select the Expanding Driver (4-8) and Washer (2 or 3) from the Camshaft Bearing Service Set (J-33049) and assemble.
4. Insert camshaft bearing service set through the front of the engine block and into the bearing.
5. Tighten the expander assembly nut until snug.
6. Push the guide cone into the front camshaft bearing to align the camshaft bearing service set.
7. Drive inner bearings from their block bores.
8. Assemble the camshaft bearing service set handle, expanding driver, and washer.
9. Insert camshaft bearing service set into the outer camshaft bearings.
10. Drive the outer bearings from the bore.

1. Assemble the tool handle, expanding driver, and washer.
2. Insert the camshaft bearing service set tool into engine block end camshaft bearings.
3. Drive the end bearings into the bore.
4. Select the expanding driver and washer from the camshaft bearing service set and assemble the tool.
5. Insert the camshaft bearing service set tool through the front of engine block and to inner bearing bores.
6. Install bearing onto the expanding driver.
7. Tighten the expander assembly nut until the tool is snug in the bearing.
8. Align the oil lubrication hole in the bearing with the oil galleries in engine block.
9. Push the guide cone into the front camshaft bearing bore to align the tool.
10. Drive bearing into bore.

1. Remove A/C belt.
2. Remove cooling fan.
3. Remove starter motor.
4. Install the Flywheel Holding Tool (J-42847) to starter bolt holes. Tighten flywheel holding tool bolts to 37 ft. lbs. (50 N.m).
5. Remove crankshaft balancer bolt and washer.
6. Install Crankshaft Balancer Protector Button (J-42846) onto the end of the crankshaft.
7. Install Harmonic Balancer Remover (J-38416-B) onto the crankshaft balancer protector button in order to remove crankshaft balancer. Place the legs of harmonic balancer remover into recesses cast into the backside of balancer inner hub. (Scheme 16)
8. Tighten center screw of the harmonic balancer remover until the crankshaft balancer is clear of the crankshaft nose.
9. Remove crankshaft balancer.
10. Remove crankshaft balancer protector button from end of crankshaft.

1. Install the balancer onto the end of the crankshaft.
2. Install the Crankshaft Balancer Installer (J-42845) to the crankshaft balancer.
3. Using the crankshaft balancer installer, install the balancer. (Scheme 16)
4. Tighten crankshaft balancer installer until crankshaft balancer is completely seated against the crankshaft sprocket.
5. Remove crankshaft balancer installer from crankshaft. (Scheme 16)
6. Install crankshaft bolt and washer to crankshaft. Tighten crankshaft balancer bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
7. Remove flywheel holding tool.
8. Install starter motor.
9. Install cooling fan.
10. Install A/C belt.

Scheme 16

1. Remove crankshaft balancer. See «CRANKSHAFT BALANCER»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
2. Remove crankshaft front cover oil seal.

1. Coat crankshaft front cover oil seal with clean engine oil.
2. Using Front Cover Oil Seal Installer (J-42851), install oil seal
3. Remove front cover oil seal installer.
4. Install crankshaft balancer. See «CRANKSHAFT BALANCER»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .

1. Remove flywheel.
2. Install guide pins from the Crankshaft Rear Seal Puller (J-43320) into the crankshaft.
3. Install crankshaft rear seal puller over the guide pins.
4. Using a suitable drill, insert 8 of the self-drilling sheet metal screws into the rear crankshaft seal, using a criss-cross pattern. The self-tapping screws are included with the crankshaft rear seal puller.
5. Thread the center bolt of the crankshaft rear seal puller into the crankshaft to remove the seal.
6. Remove guide pins from the crankshaft.

1. Ensure crankshaft is free of grit, loose rust, and burrs. Correct as needed.
2. Apply a very light film of oil onto the crankshaft sealing surface. DO NOT apply oil to sealing surface of engine block.
3. Using Crankshaft Rear Seal Installer (J-42849), install rear sea to installer.
4. Position crankshaft rear seal installer against crankshaft. Thread the attaching screws into the tapped holes in crankshaft.
5. Tighten screws securely with a screwdriver in order to ensure that the seal is installed squarely over the crankshaft.
6. Rotate the center nut until crankshaft rear seal installer bottoms.
7. Remove crankshaft rear seal installer.
8. Install flywheel.

1. Remove crankshaft position sensor bolt.
2. Apply penetrating oil to the crankshaft position sensor-to-engine block mating surface. Allow penetrating oil to soak for several minutes, to help loosen the O-ring from engine block
3. Twist sensor to break the O-ring seals loose. When removing sensor, pull sensor straight out of engine block at the same angle sensor was installed.
4. Inspect both crankshaft position sensor O-rings for cuts, cracks, tears or damage. Replace the O-rings as needed.
5. Remove crankshaft bearing cap bolts and studs, crankshaft bearing caps, crankshaft lower bearings from bearing caps, crankshaft, and upper bearings from engine block. (Scheme 17)

1. Install crankshaft upper bearings into the block. Apply clean engine oil to the bearing surfaces. (Scheme 17)
2. Install crankshaft lower bearings into the crankshaft bearing caps. Apply clean engine oil to bearing surfaces. (Scheme 17)
3. Install crankshaft. (Scheme 17)
4. Apply a 0.500" (13 mm) light film of sealant to the rear bearing cap sealing face or to rear bearing cap channel of engine block. Apply sealant to bearing cap mating surface and bearing cap channel from the rear seal bore to oil pan surface.
5. Install crankshaft bearing caps in the location the caps were marked and originally removed from. (Scheme 17)
6. Install crankshaft bearing cap bolts and studs. Tighten crankshaft bearing cap inner bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications). Tighten crankshaft bearing cap outer studs to specification. Using a Torque Angel Meter, tighten crankshaft bearing cap inner bolts an additional 90 degrees. Using a Torque Angle Meter, tighten the crankshaft bearing cap outer studs an additional 80 degrees. (Scheme 17)
7. Measure crankshaft end play as follows: Install Dial Indicator Set (J-8001) to cylinder block, with dial indicator plunger against one of the counterweights of crankshaft. Firmly thrust the end of the crankshaft first rearward then forward. This will line up the rear crankshaft bearing and crankshaft thrust surfaces. With crankshaft pushed forward, zero dial indicator. Move crankshaft rearward, and read the end play measurement on dial indicator. An optional method is to insert a feeler gauge between crankshaft and bearing surface and measure clearance. See «ENGINE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8). If correct end play cannot be obtained, inspect for the correct size crankshaft bearing has been installed. See «ENGINE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8). Inspect crankshaft thrust wall surface or surfaces for wear and/or excessive runout. Inspect crankshaft for binding. Turn crankshaft to check for binding. If crankshaft does not turn freely, loosen crankshaft bearing bolts and studs, one cap at a time, until the tight bearing is located. The following condition or conditions could cause a lack of clearance at the bearing: Burrs on crankshaft bearing cap. Foreign material between the bearing and the block. Foreign material between bearing and bearing cap. A faulty crankshaft bearing. Improper size bearing.
8. Inspect both crankshaft position sensor O-rings for cuts, cracks, tears or damage. Replace the O-rings as needed. Lubricate crankshaft position sensor O-rings with clean engine oil.
9. Install crankshaft position sensor into block. There may be a slight resistance as the O-rings seat into the engine block.
10. Apply Thread Adhesive GM (PN 12345493) to crankshaft position sensor bolt.
11. Install crankshaft position sensor bolt. Tighten crankshaft position sensor bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).

Scheme 17

1. Remove intake manifold. See «INTAKE MANIFOLD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__intake-manifold) .
2. Remove oil pump drive bolt.
3. Remove oil pump drive.
4. Clean and inspect oil pump drive.

1. Apply grease to the oil pump drive gear for ease of assembly.
2. Line up the oil pump drive, making sure that the oil pump is fully seated in engine block.
3. Install oil pump, making sure that oil pump drive is fully seated in engine block. Tighten oil pump drive bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
4. Install intake manifold. See «INTAKE MANIFOLD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__intake-manifold) .

1. Remove engine oil filter.
2. Loosen oil filter fitting using a hex wrench.
3. Remove oil filter fitting.
4. Remove oil filter bypass valves. Unstake the tangs on the oil bypass valves and remove with long nose pliers.
5. Discard oil bypass valves.

1. Install NEW oil bypass valves. Stake the tangs on the oil bypass valves.
2. Inspect oil filter fitting, replace as necessary.
3. Install oil filter fitting. Tighten oil filter fitting to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
4. Install oil filter.

OIL PAN

Note. Do not raise engine by crankshaft balancer to perform this service procedure. Damage to crankshaft balancer or crankshaft may occur.

1. On 4WD models, remove front differential. See appropriate DIFFERENTIALS article in DRIVE AXLES.
2. On all models, remove starter motor.
3. Remove oil pan skid plate bolts then the oil pan skid plate.
4. Remove crossbar.
5. Drain engine oil and remove oil level indicator.
6. Disconnect oil level sensor electrical connector. (Scheme 19)
7. Remove engine harness clip from oil pan.
8. Remove oil level sensor from oil pan.
9. Remove battery cable channel bolt.
10. Remove and reposition battery cable channel.
11. Remove oil pan bolts, oil pan and gasket.

Note. The oil pan must be installed within 5 minutes of the sealer being applied or sealer will begin to cure, causing an inadequate seal.

1. Apply Sealant GM (PN 12346286) to the sides of the front and rear crankshaft bearing caps, and on both left and right sides (4 locations total).
2. Install a NEW oil pan gasket into the oil pan groove, if required.
3. Install oil pan.
4. Install oil pan bolts. Tighten oil pan bolts in sequence and to 89 INCH lbs. (10 N.m) on the first pass and to 18 ft. lbs. (25 N.m) on the second pass. (Scheme 18)
5. Position battery cable channel into place.
6. Install battery cable channel bolt. Tighten battery cable channel bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
7. Install oil level sensor to oil pan. Tighten oil level sensor to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
8. Install engine harness clip to oil pan.
9. Connect oil level sensor electrical connector. (Scheme 19)
10. Install oil level indicator.
11. Fill engine with oil.
12. Install and tighten crossbar bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
13. Install oil pan skid plate and bolts. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
14. Install starter motor.
15. On 4WD models, install front differential. See appropriate DIFFERENTIALS article in DRIVE AXLES.

Scheme 18

Scheme 19

1. Remove oil pan. See «OIL PAN»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__oil-pan) .
2. Remove oil pump bolt.
3. Remove and separate oil pump, retainer, and driveshaft.
4. Discard driveshaft retainer.
5. Remove crankshaft oil deflector nuts.
6. Remove crankshaft oil deflector.
7. Clean and inspect oil pump.

1. Install crankshaft oil deflector.
2. Install crankshaft oil deflector nuts. Tighten crankshaft oil deflector nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
3. Assemble oil pump, driveshaft and a NEW retainer.
4. Install oil pump assembly. Position oil pump onto the locating pins.
5. Install and tighten oil pump bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
6. Install oil pan. See «OIL PAN»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__oil-pan) .

1. Remove cylinder bore ridge as necessary. Install Crankshaft Protector Button (J-42846) onto the front of crankshaft in order to turn crankshaft. Rotate crankshaft until piston is at bottom of the stroke (BDC). Place a cloth on top of piston. Perform cutting operation with Cylinder Bore Ridge Reamer (J-24270). Remove cylinder bore ridge reamer. Rotate crankshaft until the piston is at Top Dead Center (TDC). Remove cloth and cuttings. Repeat procedure for each piston.
2. Remove connecting rod nuts.
3. Remove connecting rod cap and lower connecting rod bearing.
4. Install rubber fuel line onto the connecting rod bolts to prevent contact with crankshaft.
5. Remove piston, connecting rod and upper connecting rod bearing out of the top of engine block.
6. Remove rubber fuel line from connecting rod bolts.
7. Remove remaining piston and connecting rod assemblies.
8. Remove crankshaft protector button from the front of crankshaft.

1. Coat the piston, piston rings, cylinder bore and bearing surfaces with clean engine oil.
2. Install rubber fuel line onto connecting rod bolts.
3. Install piston, connecting rod and upper connecting rod bearing through the top of engine block.
4. Install Piston Ring Compressor (J-8037) onto the piston and compress piston rings.
5. Use piston ring compressor and lightly tap the top of the piston with a wooden hammer handle.
6. Hold piston ring compressor firmly against engine block until all of the piston rings have entered cylinder bore.
7. Use a rubber fuel line in order to guide connecting rod onto crankshaft journal.
8. Remove rubber fuel line.
9. Install connecting rod cap and lower connecting rod bearing.
10. Install the new connecting rod nuts. Tighten connecting rod nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) plus an additional 90 degrees.
11. Once piston and connecting rod assemblies have been installed, lightly tap each connecting rod assembly, parallel to crank pin, in order to make sure that they have side clearance.
12. Use a feeler gauge or a dial indicator to measure the side clearance between the connecting rod caps. The rod side clearance should be 0.0151-0.0270" (0.384-0.686 mm). See «ENGINE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .

1. Remove transmission. See appropriate TRANSMISSION article.
2. Remove engine flywheel bolts.
3. Remove engine flywheel.

1. Install engine flywheel.
2. Install engine flywheel bolts.
3. Install transmission.

1. Raise and support vehicle.
2. Remove engine shield bolts and shield, if necessary.
3. Remove oil pan skid plate bolts and plate, if necessary.
4. Remove muffler. See «MUFFLER REPLACEMENT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
5. Disconnect the Connector Position Assurance (CPA) retainers.
6. Disconnect oxygen sensor electrical connectors.
7. Remove left exhaust manifold pipe nuts.
8. Remove catalytic converter.
9. Slide catalytic converter hanger out of the exhaust pipe hanger bracket.
10. Remove oxygen sensors if catalytic converter is to be replaced.

1. Apply Anti-Seize Compound GM (PN 12377953) to threads of the old oxygen sensors. Install oxygen sensors. Tighten oxygen sensors to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
2. Install a NEW exhaust seal to the exhaust manifold.
3. Install catalytic converter. Slide catalytic converter hanger into exhaust pipe hanger bracket.
4. Install left exhaust manifold pipe nuts. Tighten exhaust manifold pipe nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
5. Connect oxygen sensor electrical connectors.
6. Connect CPA retainers.
7. Install muffler. See «MUFFLER REPLACEMENT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
8. Install oil pan skid plate and bolts, if necessary. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
9. Install engine shield and bolts, if necessary. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
10. Lower vehicle.

1. Remove wheels.
2. Remove oil pan skid plate bolts and plate, if necessary.
3. Remove spare tire.
4. On vehicles equipped with electronic rear suspension, disconnect the chassis harness from the electrical connectors, electronic suspension rear position sensor and rear shock absorber.
5. Remove the left and right sensor link rods from the sensors by supporting sensor lever with your hand and twisting the link rod in order to remove it from the ball stud.
6. On all vehicles, install adjustable jack stands under rear axle.
7. Remove rear axle vent hose from rear axle (if equipped).
8. Remove vent hose swivel clip from the rear brake crossover pipe.
9. On all vehicles, remove rear shock absorbers lower bolts and nuts.
10. Lower rear axle slightly, using the adjustable jack stands, in order to remove the muffler.
11. Unclip oxygen sensor connector from the frame.
12. Disconnect the Connector Position Assurance (CPA) retainer.
13. Disconnect oxygen sensor electrical connector.
14. Remove muffler nuts.
15. Loosen exhaust pipe clamp.
16. With the aid of an assistant, support muffler.
17. Remove insulators from frame hangers.
18. Slide muffler rearward in order to remove muffler from catalytic converter.
19. Remove insulators from muffler hangers.
20. Remove exhaust manifold pipe gasket.
21. Remove oxygen sensor, if muffler is being replaced.

1. If muffler was replaced, reinstall the old oxygen sensor.
2. Apply anti-seize compound to the threads of the old oxygen sensor.
3. Install oxygen sensor and tighten to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
4. Install insulators to muffler hangers.
5. Install a new exhaust manifold pipe gasket.
6. With the aid of an assistant, slide the muffler forward in order to install the muffler to the catalytic converter.
7. Install insulators to the frame hangers.
8. Install muffler nuts, until snug.
9. Tighten exhaust pipe clamp bolt and muffler nuts. Tighten exhaust muffler nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) . Tighten exhaust pipe clamp to specification.
10. Connect oxygen sensor electrical connector.
11. Connect CPA retainer.
12. Clip oxygen sensor connector to the support.
13. Raise rear axle using adjustable jack stands.
14. Install rear shock absorbers lower bolts and nuts. Tighten lower bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
15. Remove adjustable jack stands from under the rear axle.
16. Connect vent hose swivel clip to the rear brake crossover pipe.
17. Install rear axle vent hose to rear axle, if necessary.
18. Install the left and right sensor link rods to the sensors. Using Hose Clamp Pliers (J-38185), install link rods to ball studs on sensor levers.
19. Connect the chassis harness to the electronic suspension rear position sensor and rear shock.
20. Install spare tire.
21. Install oil pan skid plate and bolts, if necessary. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
22. Install rear wheels.

1. Drain cooling system.
2. Reposition inlet hose clamp from the radiator. Remove inlet hose from radiator.
3. Reposition outlet hose clamp from radiator. Remove radiator outlet hose from radiator.
4. Remove lower fan shroud.
5. Reposition radiator vent inlet hose clamp from radiator. Remove vent inlet hose from radiator.
6. Remove engine oil cooler lines from radiator.
7. Remove transmission oil cooler lines from radiator.
8. Remove radiator mounting bolts. Remove radiator from vehicle.
9. To install, reverse removal procedure. Tighten radiator mounting bolts to 18 ft. lbs. (25 N.m). Refill and bleed cooling system. See «COOLING SYSTEM BLEEDING»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__cooling-system-bleeding) . Check for leaks and coolant level.

1. Drain cooling system.
2. Reposition inlet hose clamp at water/coolant outlet.
3. Remove inlet hose from water/coolant outlet.
4. Remove water/coolant outlet bolts.
5. Remove thermostat housing. Remove thermostat. (Scheme 20)
6. To install, reverse removal procedure. Tighten to specifications. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications). Bleed cooling system. See «COOLING SYSTEM BLEEDING»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__cooling-system-bleeding). Check for leaks and coolant level.

Scheme 20

1. Drain cooling system.
2. Remove drive belt.
3. Remove fan clutch.
4. Reposition outlet hose clamp at water pump. Remove outlet hose from water pump.
5. Reposition bypass hose clamps at water pump and water crossover. Remove bypass hose.
6. Remove water pump bolts. Remove water pump. Discard water pump gaskets.
7. To install, reverse removal procedure. Tighten to specifications. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) . Refill and bleed cooling system. See «COOLING SYSTEM BLEEDING»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__cooling-system-bleeding) . Check for leaks and coolant level.

Disassembly

1. Remove throttle body nuts and throttle body.
2. Remove and discard throttle body gasket.
3. Remove MAP sensor bolt and MAP sensor.
4. Inspect MAP sensor seal for damage.
5. Remove EGR valve nuts, EGR valve and EGR valve gasket.
6. Discard EGR valve gasket.
7. Remove EGR adapter nuts, EGR adapter and EGR adapter gasket.
8. Discard EGR adapter gasket.
9. Remove purge solenoid vacuum hose.
10. Remove purge solenoid bolt and purge solenoid.
11. Inspect purge solenoid seal for damage. Replace seal as needed.

Cleaning & Inspection

1. Clean intake manifold in an approved solvent. Clean debris out of all bolt holes. Clean intake manifold gasket sealing surfaces. Clean all carbon from EGR passages. Clean all intake manifold ports.
2. Dry intake manifold with compressed air.
3. Inspect intake manifold bolt holes for cracks and/or damage, MAP sensor sealing surface for damage, purge solenoid sealing surface for damage, or purge solenoid bolt has a sealer that may come off during removal of bolt. Ensure all sealant is removed from the bolt hole. Check intake manifold-to-cylinder head sealing surfaces for damage, EGR adapter mounting surface for damage, and throttle body studs for damage. Replace as necessary. Check throttle body mounting surface for damage, or oil fill tube hole for signs of leakage. Reseal as necessary. Check PCV port for debris or varnish buildup and EGR pipe for damage.

Assembly

1. Apply a very light film of clean engine oil to purge solenoid seal.
2. Install purge solenoid.
3. Apply thread adhesive to purge solenoid bolt threads.
4. Install and tighten purge solenoid bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
5. Install purge solenoid vacuum hose.
6. Install EGR adapter gasket.
7. Install EGR adapter.
8. Install and tighten EGR adapter nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
9. Install EGR valve gasket and EGR valve.
10. Install and tighten EGR valve nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
11. Install MAP sensor. Tighten MAP sensor bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .
12. Install throttle body gasket. Install throttle body.
13. Install throttle body nut and tighten to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) .

1. Use Valve Spring Compressor (J-5892-D) to compress valve springs.
2. Remove valve stem keys. (Scheme 21)
3. Release and remove the valve spring compressor.
4. Remove valve cap, valve spring, positive valve stem seal from valve guide, valve rotator, and valve. (Scheme 21)
5. Disconnect Engine Coolant Temperature (ECT) sensor from bracket.
6. Remove ECT sensor from right cylinder head.
7. Remove ECT sensor bracket and bolt.
8. Remove cylinder head coolant hole plug from the left cylinder head.

Cylinder Head Cleaning Procedure

1. Clean valve stems and heads on a buffing wheel.
2. Clean valve stem keys, valve spring cap, valve spring, valve rotators, valve and cylinder head with solvent.
3. Dry components with compressed air.
4. Use Carbon Removal Brush (J-8089) in order to clean carbon from combustion chambers.

Valve Inspection Procedure

Inspect cylinder head for damaged gasket surfaces, damaged threaded bolt holes, burnt or eroded areas in combustion chamber, cracks in exhaust ports and combustion chambers, external cracks in water chamber, restrictions in intake or exhaust passages and restrictions in cooling system passages.

Flatness Measurement Procedure

1. Measure cylinder head for warpage with a straight edge and feeler gauge. A cylinder head block deck with warpage in excess of 0.002" (0.050 mm) within a 6.0" (150.0 mm) area must be repaired or replaced. A cylinder head intake manifold deck with warpage in excess of 0.003" (0.080 mm) must be repaired or replaced. See «ENGINE BLOCK (PRODUCTION SPECIFICATIONS)»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
2. See «CYLINDER HEAD»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table, for resurfacing specifications.
3. A cylinder head that requires excessive resurfacing must be replaced.

Valve Spring Inspection & Measurement

1. Inspect valve springs for broken coils or coil ends.
2. Use Valve Spring Tester (J-9666) in order to measure the valve spring force. See «VALVE SYSTEM»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
3. If valve spring tension is low, use a shim to increase tension.
4. Recheck valve spring tension, a valve spring that does not meet specification must be replaced.

Valve Guide Measurement Procedure

1. Measure valve stem-to-guide clearance. Clamp Dial Indicator on to the exhaust port side of the cylinder head. Locate the indicator so that the movement of the valve stem from side to side, crosswise to the cylinder head, will cause a direct movement of the indicator stem. Drop the valve head about 0.064" (1.6 mm) off the valve seat. Use light pressure when moving the valve stem from side to side in order to obtain a clearance reading. See «VALVES»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) .
2. Valve guide with excessive clearance must be repaired. See «VALVE GUIDE REAMING PROCEDURE FOR OVERSIZED VALVE STEMS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__valve-guide-reaming-procedure-for-oversized) .
3. Replace cylinder head if valve guide cannot be repaired or reamed to accept an oversize valve stem.

Valve Guide Reaming Procedure For Oversized Valve Stems

1. Ream valve guide as necessary to achieve proper valve stem-to-guide clearance with the new, oversized valve stems.
2. Always recondition the valve seat after reaming valve guide bores or installing new valves.
3. Replace cylinder head if valve guide cannot be repaired or reamed to accept an oversize valve stem.

Valve Reconditioning Procedure

1. Replace valve if valve stem shows excessive wear or is warped.
2. Reface pitted valves on a valve refacing machine in order to insure the correct relationship between the head and stem.
3. Replace valve if the edge of the head is less than 0.031" (0.79 mm) thick after grinding.

Valve Seat Reconditioning Procedure

1. Recondition valve seats.
2. The valves must seat perfectly for the engine to deliver optimum power and performance.
3. Ensure that valve seat and valve are not shrouded after valve seat reconditioning. Adequate flow past the valve seat and valve is essential for cooling the valve head and valve seat area.
4. Correct contact between each valve and its seat in the cylinder head is also essential to ensure that the heat in the valve head is properly carried away.
5. The valve seats should be concentric to within 0.002" (0.050 mm) total indicator runout.

Cylinder Boring

1. Before you use any type of boring bar, clean the top of the cylinder block in order to remove any dirt or burrs.
2. Carefully follow the instructions furnished by the manufacturer regarding use of equipment.
3. When you rebore cylinders, make sure all crankshaft bearing caps are in place. Tighten the bearing caps to the proper torque in order to avoid distortion of the bores in the final assembly. The crankshaft must be removed prior to cylinder boring.
4. When you take the final cut with a boring bar, leave 0.001" (0.03 mm) on the diameter for finish honing. This gives the required position to the cylinder clearance specifications. (Carefully perform the honing and boring operation in order to maintain the specified clearances between pistons, rings, and cylinder bores).

Cylinder Honing

1. When honing the cylinders, follow the manufacturer's recommendations for equipment use, cleaning, and lubrication. Use only clean, sharp stones of the proper grade for the amount of material you remove. Dull, dirty stones cut unevenly and generate excessive heat. Do not hone to a final grade with a coarse or medium-grade stone. Leave sufficient metal so that all stone marks may be removed with fine grade stones. The re-honed surface finish should be 10-20 micro inch (0.25-0.50 micrometer). Perform final honing with a fine-grade stone and hone the cylinder in a cross hatch pattern at 20 to 30 degrees to obtain the proper clearance.
2. During the honing operation, thoroughly clean the cylinder bore. Repeatedly check the cylinder bore for fit with the selected oversized piston. All measurements of the cylinder bore should be made with the components at normal room temperature.
3. To eliminate taper in the cylinder, when honing, make full strokes of the hone in the cylinder. Repeatedly check the measurement at the top, the middle, and the bottom of the bore. The finish marks should be clean but not sharp. The finish marks should be free from embedded particles and torn or folded metal.
4. When finished, the reconditioned cylinder bores should have less than or meet the specified out-of-round or taper requirements.
5. After final honing and before the piston is checked for fit, clean the bores with hot water and detergent. Scrub the bores with a stiff bristle brush and rinse the bores thoroughly with hot water. Do not allow any abrasive material to remain in the cylinder bores. Abrasive material may cause premature wear of new piston rings and cylinder bores. Abrasive material will contaminate the engine oil and may cause premature wear of the bearings. After washing the cylinder bore, dry the bore with a clean shop towel.
6. Perform final measurements of the cylinder bore.
7. Permanently mark the piston for the specific cylinder to which it has been fitted.
8. Apply clean engine oil to each cylinder bore in order to prevent rusting.

1. Lubricate valve stems with clean engine oil.
2. Insert valves into their proper locations.
3. Install necessary valve spring shims onto the cylinder head, if applicable.
4. Lubricate rotators with clean engine oil.
5. Install rotators over the guide and on top of the cylinder head or valve spring shims, if applicable.
6. Lubricate valve stem seal and the outside diameter of the valve guide with clean engine oil.
7. Install valve stem oil seals over the valve tip and onto the valve guides using Valve Stem Seal Installer (J-43105). Tap the valve stem seal onto the valve guide until the valve stem seal installer fully seats the seal.
8. Install valve springs and valve spring caps. (Scheme 21)
9. Use Valve Spring Compressor (J-5892-D) in order to compress the valve spring. Compress the spring enough to clearly see the valve stem key grooves of the valve.
10. Install valve stem keys. Use grease to hold the keys in place. Ensure that keys seat properly in the upper groove of valve stem.
11. Release and remove the valve spring compressor.
12. Lightly tap end of valve stem with a plastic-faced hammer to seat the keys.
13. Apply Sealant GM (PN 12346004) to the threads of the ECT sensor.
14. Install ECT sensor into the right cylinder head. Tighten ECT sensor to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
15. Install ECT sensor bracket and bolt. Tighten the ECT sensor bracket bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).
16. Install cylinder head coolant hole plug into the left cylinder head. Tighten cylinder head coolant hole plug to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications).

Scheme 21

Crankshaft Inspection

1. Clean crankshaft in solvent. Remove all sludge or restrictions from the oil passages.
2. Dry crankshaft and bearings with compressed air.
3. Inspect the crankshaft. Crankshaft journals should be smooth with no evidence of scoring or damage, deep grooves, scratches or uneven wear, pitted surfaces, wear or damage to thrust journal surfaces, scoring or damage to rear seal surface, restrictions to oil passages or damage to threaded bolt holes.
4. Inspect crankshaft pin for damage. Measure for proper installed height. Check for correct height, see «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table. Replace crankshaft pin, if damaged.
5. Inspect reluctor wheels for cracked, bent or broken teeth. Measure between the crankshaft shoulder and the front reluctor wheel. Measure between front and rear reluctor wheels. The maximum allowable gap is 0.006" (0.15 mm). See «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
6. Measure crankshaft main journals and crank pins for out-of-round and taper.
7. Using a suitable fixture, support crankshaft. Measure crankshaft runout using a Magnetic Base Dial Indicator (J-7872) . For correct crankshaft runout not to be exceeded, see «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
8. Inspect crankshaft thrust wall surface for wear and/or excessive runout. See «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.

Crankshaft & Connecting Rod Bearing Inspection

1. Inspect bearings for craters or pockets. Flattened sections on bearing halves also indicate fatigue.
2. Inspect bearings for excessive scoring or discoloration.
3. Inspect bearings for dirt or debris embedded into bearing material.
4. Inspect bearings for improper seating indicated by bright, polished sections of the bearings.

Crankshaft & Connecting Rod Bearing Clearance Measurement

The crankshaft and connecting rod bearings are of the precision insert type and do not use shims for adjustment. Crankshafts with journals that measure less than minimum specifications must be replaced.

Micrometer Method For Crankshaft Bearings

1. Measure the crankshaft main journal diameter with a micrometer in several places along the length approximately 90 degrees apart, minimum of 4 places, and average the measurements.
2. Determine taper and the out-of-round. See «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
3. Install NEW crankshaft bearings into crankshaft bearing caps and engine block.
4. Install crankshaft bearing caps and crankshaft bearing cap bolts and studs. Tighten crankshaft bearing cap inner bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) . Tighten the crankshaft bearing cap outer studs to specification. Using a Torque Angle Meter (J-36660-A) , tighten crankshaft bearing cap inner bolts an additional 90 degrees. Using the torque angle meter, tighten the crankshaft bearing cap outer studs an additional 80 degrees.
5. Measure crankshaft bearing Inside Diameter (ID) using an inside micrometer. Measure at a minimum of 4 places and average the measurements.
6. In order to determine the crankshaft bearing clearance, subtract the crankshaft journal diameter from the crankshaft bearing ID.
7. Compare crankshaft bearing clearance to specifications. See «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
8. If crankshaft bearing clearances exceeds specifications, install undersize crankshaft bearings to achieve the correct clearance.
9. Measure new crankshaft bearing inside diameter using an inside micrometer.
10. Replace crankshaft if the proper clearances cannot be obtained with standard size bearings.

Micrometer Method For Connecting Rod Bearings

1. Measure crank pin diameter with a micrometer in several places along the length, approximately 90 degrees apart, minimum of 4 places, and average the measurements.
2. Determine the taper and the out-of-round. See «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
3. Install NEW connecting rod bearings into the connecting rod cap and the connecting rod.
4. Install connecting rod cap and the original, used, nuts. Tighten the connecting rod nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) . Tighten the connecting rod nuts an additional 90 degrees.
5. Measure connecting rod bearing Inside Diameter (ID) using an inside micrometer.
6. Compare the connecting rod bearing clearance specifications. See «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
7. If the connecting rod bearing clearances exceed specifications, replace components as required.

Measuring Crankshaft Bearing Clearance Using Plastigage®

1. Install the crankshaft and the new crankshaft bearings into the block, making sure not to damage the reluctor rings of the crankshaft.
2. Install gaging plastic the full width of the crankshaft journal.
3. Install crankshaft bearing caps and the crankshaft bearing cap bolts and studs. Tighten the crankshaft bearing cap inner bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) . Tighten the crankshaft bearing cap outer studs to specification. Using a Torque Angle Meter, tighten the crankshaft bearing cap inner bolts an additional 90 degrees. Using torque angle meter, tighten the crankshaft bearing cap outer studs an additional 80 degrees.
4. Remove crankshaft bearing cap bolts and the crankshaft bearing caps. The gaging plastic may adhere to either the crankshaft journal or the crankshaft bearing surfaces.
5. On the edge of the gaging plastic envelope there is a graduated scale. Without removing the gaging plastic, measure the compressed width at the widest point.
6. If the flattened gaging plastic tapers toward the middle or the ends, there may be a difference in clearance indicating taper, low spot or other irregularity of the crankshaft bearing or the crankshaft journal. Normally the crankshaft journals wear evenly and are not out-of-round. However, if a crankshaft bearing is being fitted to an out-of-round crankshaft journal, see «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table, be sure to fit to the maximum diameter of the crankshaft journal. If the crankshaft bearing is fitted to the minimum diameter and the crankshaft journal is excessively out-of-round, the interference between the crankshaft bearing and the crankshaft journal will result in rapid crankshaft bearing failure.
7. Compare the crankshaft bearing clearance to the specifications. See «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
8. If crankshaft bearing clearances exceeds specifications, replace components as required.
9. Measure new crankshaft bearing inside diameter using the same method.
10. Replace crankshaft if the proper clearances cannot be obtained with standard size bearings.
11. Remove flattened gaging plastic.
12. Measure remaining crankshaft journals.

Measuring Connecting Rod Bearing Clearance Using Plastigage®

1. Install connecting rod bearings into the connecting rod and the connecting rod cap.
2. Using rubber fuel line over the connecting rod bolts, install piston and connecting rod assembly onto crank pin journal.
3. Install gaging plastic the full width of the crank pin journal.
4. Install connecting rod cap and original, used, nuts. Tighten connecting rod nuts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8__torque-specifications) . Tighten connecting rod nuts an additional 90 degrees.
5. Remove connecting rod nuts and cap. The gaging plastic may adhere to either the crank pin journal or connecting rod bearing surface.
6. On the edge of the gaging plastic envelope there is a graduated scale. Without removing the gaging plastic, measure the compressed width at the widest point. If the flattened gaging plastic tapers toward the middle or the ends, there may be a difference in clearance indicating taper, low spot or other irregularity of the crankshaft bearing or the crank pin journal.
7. Normally the crank pin journals wear evenly and are not out-of-round. However, if a connecting rod bearing is being fitted to an out-of-round crank pin journal, see «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table. Be sure to fit to the maximum diameter of the crank pin journal. If the connecting rod bearing is fitted to the minimum diameter and the crank pin journal is excessively out-of-round, the interference between the connecting rod bearing and the crank pin journal will result in rapid connecting rod bearing failure
8. Compare connecting rod bearing clearance to specifications. See «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
9. If connecting rod bearing clearances exceed specifications, replace components as required.
10. Remove flattened gaging plastic.
11. Measure remaining crank pin journals.

Measuring Crankshaft End Play

1. Install the Magnetic Base Dial Indicator, or equivalent to the cylinder block, with the dial indicator plunger against one of the counterweights of the crankshaft.
2. Firmly thrust the end of the crankshaft first rearward then forward. This will line up the rear crankshaft bearing and the crankshaft thrust surfaces.
3. With crankshaft pushed forward, zero the dial indicator. Move crankshaft rearward and read the end play measurement on the dial indicator. An optional method is to insert a feeler gauge between the crankshaft and bearing surface and measure clearance. See «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
4. If the correct end play cannot be obtained, inspect crankshaft thrust wall surface or surfaces for wear and/or excessive runout.
5. Inspect crankshaft for binding. Turn crankshaft to check for binding. If crankshaft does not turn freely, loosen crankshaft bearing bolts and studs, one cap at a time, until the tight bearing is located. The following condition or conditions could cause a lack of clearance at the bearing: Burrs on crankshaft bearing cap. Foreign matter between crankshaft bearing and block or crankshaft bearing cap. A faulty crankshaft bearing.

Measuring Connecting Rod Side Bearing

1. Install the Magnetic Based Dial Indicator, or equivalent to the cylinder block, with the dial indicator plunger against the side of the pair of connecting rods.
2. With connecting rods pushed forward, zero the dial indicator. Firmly move the pair of connecting rods side to side and read the measurement on dial indicator. An optional method is to insert a feeler gauge between the connecting rod caps and measure connecting rod side clearance. See «CRANKSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.

CRANKSHAFT BALANCER CLEANING & INSPECTION

1. Clean crankshaft balancer in solvent.
2. Dry crankshaft balancer with compressed air.
3. Inspect crankshaft balancer for damaged belt grooves, debris in belt grooves, worn, grooved, or damaged hub seal surface. Minor imperfections on hub seal surface may be removed with a polishing compound or fine grade of emery cloth. Crankshaft balancer hub seal surface with excessive scoring, grooves, rust or other damage must be replaced. Worn, chunking or deteriorated rubber between the hub and pulley must be replaced.
4. Repair or replace crankshaft balancer as necessary.

PISTON, CONNECTING ROD, & BEARINGS CLEANING & INSPECTION

1. Clean piston, connecting rod and connecting rod cap in solvent.
2. Dry components with compressed air.
3. Clean piston ring grooves with a suitable ring groove cleaning tool.
4. Clean piston oil lubrication holes and slots.
5. Inspect piston for eroded areas on the top of the piston, scuffed or damaged skirt, cracks in piston ring lands, piston skirt, or pin bosses. Inspect piston ring grooves for nicks, burrs, or other warpage which may cause piston ring to bind.
6. Inspect piston pin for scoring, wear or other damage.
7. Measure piston ring-to-piston ring groove side clearance. See «PISTON RING COMPRESSION»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table. Insert edge of the piston ring into the piston ring groove. Roll the piston ring completely around the piston. If binding is caused by a distorted piston ring groove, MINOR imperfections may be removed with a fine file. If binding is caused by a distorted piston ring, replace the piston ring.
8. Measure piston ring side clearance with a feeler gauge.
9. If side clearance is too small, try another piston ring set.
10. If the proper piston ring-to-piston ring groove clearance cannot be achieved, replace the piston and pin assembly.
11. Inspect connecting rod for an out-of-round bearing bore.
12. Inspect connecting rod for twisting.
13. Inspect connecting rod for damage to the connecting rod bolt threads.
14. Measure the piston compression ring end gap. Place the compression ring into the cylinder bore. Push the compression ring into the cylinder bore to approximately 0.25" (6.5 mm) above the ring travel. The ring must be square to the cylinder wall. Use a feeler gauge in order to measure the end gap. Select another size ring set if the end gap exceeds specifications.

CAMSHAFT BEARING CLEANING & INSPECTION

1. Clean camshaft in solvent.
2. Dry camshaft with compressed air.
3. Inspect camshaft retainer plate for damage.
4. Inspect camshaft for camshaft bearing journals that are worn, scored, and/or damaged.
5. Measure camshaft journals with a micrometer. See «CAMSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
6. Measure for excessive camshaft runout using a Magnetic Based Dial Indicator. Mount camshaft in a suitable fixture. Use the Magnetic Based Dial Indicator, in order to measure for a bent camshaft. See «CAMSHAFT»(/chevrolet/avalanche/i-2001-2006/remont/mechanical/#engine-mechanical-81l-v8) table.
7. Replace camshaft if runout exceeds specifications.
8. Inspect camshaft bearings, 1-5, for serviceability.
9. Replace camshaft bearings, if necessary..

Valve Rocker Arm & Push Rod Cleaning & Inspection

1. Clean components with cleaning solvent.
2. Dry components with compressed air.
3. Inspect valve rocker arms for wear or scoring in the ball area.
4. Inspect valve rocker arm push rod sockets and valve stem tip mating surfaces.
5. Inspect valve rocker arm ball for wear or scoring. These surfaces should be smooth with no scoring or exceptional wear.
6. Inspect push rods for worn or scored ends. These surfaces should be smooth with no scoring or exceptional wear.
7. Inspect push rods for bends. Roll push rods on a flat surface to determine if push rod is bent. If it rolls smoothly, it is okay. If push rod does not roll smoothly, replace push rod.
8. Inspect push rod oil passages for restrictions. Clean out the push rod tube with compressed air. Inspect by looking through the push rod tube for obstructions. A clear push rod will allow light through. Replace push rod(s) that cannot be cleaned out.
9. Inspect rocker arm studs for damaged threads, or excessive wear or damage made from contact between the rocker arm and rocker arm stud.
10. Valve rocker arm studs with excessive wear and/or damage must be replaced.
11. Inspect push rod guides for wear between push rod and push rod guide, bent push rod guide, or cracks.
12. Push rod guides with excessive wear and/or damage must be replaced.

Valve Lifters & Guides Cleaning & Inspection

1. Clean components in cleaning solvent.
2. Dry components with compressed air.
3. Inspect valve lifters for a damaged, mispositioned or broken clip. Inspect for a scored or worn push rod socket, or a severely scuffed or worn lifter body. If valve lifter body shows scuffing or wear, inspect engine block valve lifter bores for wear or damage, flat spots on roller, a loose pin or plugged oil hole.
4. If flat spots are found on the lifter(s), inspect the corresponding lobe on the camshaft for damage.
5. Inspect valve lifter guides for excessive guide slot side wear, cracks or damage.
6. Inspect valve lifter guide retainer for wear, damage, or stress cracking in the leg areas. Check for wear or damage around the retainer bolt holes.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

GENERAL SPECIFICATIONS

GENERAL SPECIFICATIONS

CYLINDER HEAD SPECIFICATIONS

CYLINDER HEAD

EXHAUST MANIFOLD SPECIFICATIONS

EXHAUST MANIFOLD

ENGINE BLOCK SPECIFICATIONS

CYLINDER BORE

ENGINE BLOCK (PRODUCTION SPECIFICATIONS)

PISTON SPECIFICATIONS

PISTON

PISTON RING COMPRESSION SPECIFICATIONS

PISTON RING COMPRESSION

PISTON RING OIL CONTROL SPECIFICATIONS

PISTON RING OIL CONTROL

PISTON PIN SPECIFICATIONS

PISTON PIN

CRANKSHAFT SPECIFICATIONS

CRANKSHAFT

CAMSHAFT SPECIFICATIONS

CAMSHAFT

ENGINE VALVE SYSTEM SPECIFICATIONS

VALVE SYSTEM

See also:
• FUEL PRESSURE RELEASE
• MUFFLER REPLACEMENT
• TORQUE SPECIFICATIONS
• INTAKE MANIFOLD
• COOLING SYSTEM BLEEDING
• CAMSHAFT BEARING CLEANING & INSPECTION
• OIL PAN
• VALVE GUIDE REAMING PROCEDURE FOR OVERSIZED VALVE STEMS