Engine Mechanical - 8.1L: Diagnosis Chevrolet Silverado Classic 3500

Diagnostic Starting Point - Engine Mechanical

Begin the system diagnosis by reviewing the Disassembled Views , Engine Component Description , Lubrication Description , New Product Information , and the . Reviewing the description and operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the description and operation information will also help you determine if the condition described by the customer is normal operation. Refer to Symptoms - Engine Mechanical in order to identify the correct procedure for diagnosing the system and where the procedure is located.

Strategy Based Diagnostics

1. Perform a «Diagnostic System Check - Vehicle»(ref-277883-S07139257572008012100000) before using the symptom tables, if applicable.
2. Review the system operations in order to familiarize yourself with the system functions. Refer to «Disassembled Views»(ref-277941-S31159949942008012100000) , «Engine Component Description»(ref-277941-S11087738732008012100000) , , «Lubrication Description»(ref-277941-S32560604052008012100000) and «New Product Information»(ref-277941-S25622687272008012100000) .

All diagnosis on a vehicle should follow a logical process. Strategy based diagnostics is a uniform approach for repairing all systems. The diagnostic flow may always be used in order to resolve a system condition. The diagnostic flow is the place to start when repairs are necessary. For a detailed explanation, refer to Strategy Based Diagnosis .

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the engine. Refer to «Checking Aftermarket Accessories»(ref-277884-S30236091172008012100000) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
3. Inspect for the correct oil level, proper oil viscosity, and correct filter application.
4. Verify the exact operating conditions under which the condition exists. Note factors such as engine RPM, ambient temperature, engine temperature, amount of engine warm-up time, and other specifics.
5. Compare the engine sounds, if applicable, to a known good engine and ensure you are not trying to correct a normal condition.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Base Engine Misfire without Internal Engine Noises»(ref-277941-S40291052312008012100000)
2. «Base Engine Misfire with Abnormal Internal Lower Engine Noises»(ref-277941-S30915102702008012100000)
3. «Base Engine Misfire with Abnormal Valve Train Noise»(ref-277941-S21585126402008012100000)
4. «Base Engine Misfire with Coolant Consumption»(ref-277941-S00308116952008012100000)
5. «Base Engine Misfire with Excessive Oil Consumption»(ref-277941-S03740212762008012100000)
6. «Engine Noise on Start-Up, but Only Lasting a Few Seconds»(ref-277941-S29731610962008012100000)
7. «Upper Engine Noise, Regardless of Engine Speed»(ref-277941-S06290109862008012100000)
8. «Lower Engine Noise, Regardless of Engine Speed»(ref-277941-S41928270552008012100000)
9. «Engine Noise Under Load»(ref-277941-S38473573662008012100000)
10. «Engine Will Not Crank - Crankshaft Will Not Rotate»(ref-277941-S26227247892008012100000)
11. «Coolant in Combustion Chamber»(ref-277941-S13288694312008012100000)
12. «Coolant in Engine Oil»(ref-277941-S39876770392008012100000)
13. «Engine Compression Test»(ref-277941-S15968547152008012100000)
14. «Cylinder Leakage Test»(ref-277941-S20960280932008012100000)
15. «Oil Consumption Diagnosis»(ref-277941-S25384194112008012100000)
16. «Oil Pressure Diagnosis and Testing»(ref-277941-S41659126432008012100000)
17. «Drive Belt Chirping, Squeal, and Whine Diagnosis»(ref-277941-S38385461242008012100000)
18. «Drive Belt Rumbling and Vibration Diagnosis»(ref-277941-S13322067782008012100000)
19. «Drive Belt Falls Off and Excessive Wear Diagnosis»(ref-277941-S38892414412008012100000)

Engine Compression Test

1. Disconnect the ignition coil wire harness connector at the front of the engine on the left cylinder bank and at the rear of the engine at the right cylinder bank.
2. Disconnect the fuel injector electrical harness connector at the rear of the intake manifold.
3. Remove all spark plugs.
4. Block the throttle plate wide open.
5. Charge the battery, if the battery is not fully charged.
6. Start with the compression gage at 0, then crank the engine through 4 compression strokes, 4 puffs.
7. Make the compression test the same for each cylinder. Record the reading. The minimum compression in any 1 cylinder should not be less than 70 percent of the highest cylinder. No cylinder should read less than 690 kPa (100 psi). For example, if the highest pressure in any 1 cylinder is 1 035 kPa (150 psi), the lowest allowable pressure for any other cylinder would be 725 kPa (105 psi), (1035 x 70% = 725) (150 x 70% = 105).
8. If some cylinders have low compression, inject approximately 15 ml (1 tablespoon) of engine oil into the combustion chamber through the spark plug hole. Normal - Compression builds up quickly and evenly to the specified compression for each cylinder. Piston Rings Leaking - Compression is low on the first stroke, then compression builds up with the following strokes, but does not reach normal. Compression improves considerably when you add oil. Valves Leaking - Compression is low on the first stroke. Compression usually does not build up on the following strokes. Compression does not improve much when you add oil. If 2 adjacent cylinders have lower than normal compression, and injecting oil into the cylinders does not increase the compression, the cause may be a head gasket leaking between the 2 cylinders.

Cylinder Leakage Test

1. Disconnect the battery ground negative cable.
2. Remove the spark plugs. Refer to «Spark Plug Replacement»(ref-277874-S39581815162008012100000) .
3. Rotate the crankshaft to place the piston in the cylinder being tested at top dead center (TDC) of the compression stroke.
4. Install the J 35667-A or equivalent.
5. Apply shop air pressure to the J 35667-A and adjust according to the manufacturers instructions.
6. Record the cylinder leakage value. Cylinder leakage that exceeds 25 percent is considered excessive and may require component service. In excessive leakage situations, inspect for the following conditions: Air leakage sounds at the throttle body or air inlet hose that may indicate a worn or burnt intake valve or a broken valve spring. Air leakage sounds at the exhaust system tailpipe that may indicate a worn or burnt exhaust valve or a broken valve spring. Air leakage sounds from the crankcase, oil level indicator tube, or oil fill tube that may indicate worn piston rings, a damaged piston, a worn or scored cylinder bore, a damaged engine block, or a damaged cylinder head. Air bubbles in the cooling system may indicate a damaged cylinder head or a damaged cylinder head gasket.
7. Perform the leakage test on the remaining cylinders and record the values.

Oil Consumption Diagnosis

Excessive oil consumption, not due to leaks, is the use of greater than 0.95 liter (1 quart) of engine oil within 379 liters (100 gallons) of fuel used. However, during initial engine break-in periods 5 000-6 500 kilometers (3,000-4,000 miles) oil consumption may exceed 1.9 liters (2 quarts) or greater per 379 liters (100 gallons) of fuel used. The causes of excessive oil consumption include the following conditions

1. External oil leaks Tighten bolts and/or replace gaskets and oil seals, as necessary.
2. Incorrect oil level or improper reading of the oil level indicator With the vehicle on a level surface, allow adequate drain down time and measure for the correct oil level.
3. Improper oil viscosity Use recommended SAE viscosity for the prevailing temperatures.
4. Continuous high speed driving and/or severe usage
5. Crankcase ventilation system restrictions or malfunctioning components
6. Valve guides and/or valve stem oil seals worn, or the seal omitted Ream the guides and install oversize service valves and/or new valve stem oil seals.
7. Piston rings broken, improperly installed, worn, or not seated properly Allow adequate time for the rings to seat and replace broken or worn rings, as necessary.
8. Piston improperly installed or piston size is incorrectly selected

Oil Pressure Diagnosis and Testing

1. With the vehicle on a level surface, allow adequate drain down time, 2-3 minutes, and measure for the proper engine oil level. An overfull oil level causes aeration within the oil.
2. Add the recommended grade engine oil GM P/N 12345610, (Canadian P/N 993193), or equivalent, and fill the crankcase until the oil level measures FULL on the oil level indicator.
3. Operate the engine and verify low or no oil pressure on the vehicle oil pressure gage or oil indicator lamp. Listen for a noisy valve train or knocking noise.
4. Inspect for the following conditions: Engine oil diluted by moisture or unburned fuel mixtures Improper engine oil viscosity for the expected temperature Incorrect or faulty oil pressure gage sensor Incorrect or faulty oil pressure gage Plugged oil filter Malfunctioning oil filter bypass valve
5. Remove the oil pressure gage sensor or another engine block oil gallery plug.
6. Install an oil pressure gage and measure the engine oil pressure.
7. If the engine oil pressure is below specifications, inspect the engine for 1 or more of the following conditions: Oil pump worn or dirty Malfunctioning oil pump pressure relief valve Oil pump screen loose, plugged, or damaged Excessive bearing clearance or worn bearings Cracked, porous, or restricted oil galleries Engine block oil gallery plugs missing or incorrectly installed Broken valve lifters

Oil Leak Diagnosis

Oil Leak Diagnosis

Crankcase Ventilation System Inspection/Diagnosis

A plugged positive crankcase ventilation (PCV) pipe/passage way may cause

1. Rough idle
2. Stalling or slow idle speed
3. Oil leaks
4. Sludge in the engine

Diagnostic Aids

1. A chirping or squeal noise may be intermittent due to moisture on the drive belts or the pulleys. It may be necessary to spray a small amount of water on the drive belts in order to duplicate the customers concern. If spraying water on the drive belt duplicates the symptom, cleaning the belt pulleys may be the probable solution.
2. If the noise is intermittent, verify the accessory drive components by varying their loads making sure they are operated to their maximum capacity. An overcharged A/C system, power steering system with a pinched hose or wrong fluid, or a generator failing are suggested items to inspect.
3. A chirping, squeal or whine noise may be caused by a loose or improper installation of a body or suspension component. Other items of the vehicle may also cause the noise.
4. The drive belts will not cause a whine noise.

The accessory drive components can have an affect on engine vibration. Vibration from the engine operating may cause a body component or another part of the vehicle to make rumbling noise. Vibration can be caused by, but not limited to the air conditioning (A/C) system over charged, the power steering system restricted or the incorrect fluid, or an extra load on the generator. To help identify an intermittent or an improper condition, vary the loads on the accessory drive components.

The drive belt may have a rumbling condition that can not be seen or felt. Sometimes replacing the drive belt may be the only repair for the symptom.

If replacing the drive belt, completing the diagnostic table, and the noise is only heard when the drive belts are installed, there might be an accessory drive component with a failure. Varying the load on the different accessory drive components may aid in identifying which component is causing the rumbling noise.

If the drive belt repeatedly falls off the drive belt pulleys, this is because of pulley misalignment.

An extra load that is quickly applied on released by an accessory drive component may cause the drive belt to fall off the pulleys. Verify the accessory drive components operate properly.

If the drive belt is the incorrect length, the drive belt tensioner may not keep the proper tension on the drive belt.

Excessive wear on a drive belt is usually caused by an incorrect installation or the wrong drive belt for the application.

Minor misalignment of the drive belt pulleys will not cause excessive wear, but will probably cause the drive belt to make a noise or to fall off.

Excessive misalignment of the drive belt pulleys will cause excessive wear but may also make the drive belt fall off.

Drive Belt Tensioner Diagnosis

1. Remove the drive belt(s). Refer to «Drive Belt Replacement - Accessory»(ref-277941-S02332021392008012100000) or «Drive Belt Replacement - Air Conditioning»(ref-277941-S06661750352008012100000) .
2. Position a hex-head socket on the belt tensioner pulley bolt head.
3. Move the drive belt tensioner through its full travel. The movement should feel smooth. There should be no binding. The tensioner should return freely.
4. If any binding is observed, replace the drive belt tensioner(s). Refer to «Drive Belt Tensioner Replacement - Accessory»(ref-277941-S04400394372008012100000) or «Drive Belt Tensioner Replacement - Air Conditioning»(ref-277941-S28070877712008012100000) .
5. Install the drive belt(s). Refer to «Drive Belt Replacement - Accessory»(ref-277941-S02332021392008012100000) or «Drive Belt Replacement - Air Conditioning»(ref-277941-S06661750352008012100000) .

Engine Mount Inspection

Note. Broken or deteriorated mounts can cause misalignment and destruction of certain drive train components. When a single mount breaks, the remaining mounts are subjected to abnormally high stresses.

Note. When raising or supporting the engine for any reason, do not use a jack under the oil pan, any sheet metal, or the crankshaft pulley. Due to the small clearance between the oil pan and the oil pump screen, jacking against the oil pan may cause the pan to be bent against the pump screen. This will result in a damaged oil pickup unit.

1. Measure the engine movement at the engine mount in order to check for damage to the rubber portions of the mount. Apply the park brake. Start the engine. Firmly apply and hold the primary brakes. Have an assistant stand to the side of the vehicle in order to observe for engine movement. Slightly load the engine, shifting from drive to reverse a few times If the engine moves more than 24 mm (0.945 in) from the at rest position, in either direction, check for loose engine mount bolts.
2. If the engine mount bolt torque is within specifications, check the condition of the engine mount.
3. Replace the engine mount if any of the following conditions exist: Heat check cracks cover the rubber cushion surface. The rubber cushion is separated from the metal plate of the mount. There is a split through the rubber cushion.

Engine Block Cleaning and Inspection

1. Boil the cylinder block in caustic solution.
2. Flush the cylinder block with clean water or steam.
3. Clean the following areas: All gasket surfaces Refer to «Replacing Engine Gaskets»(ref-277938-S01985332132008012100000) . Cylinder bores Remove excessive cylinder ring ridge, as required. Main bearing caps Oil galleries Remove all sludge or restrictions. Scale deposits from the coolant passages All dirt or debris from threaded bolt holes
4. Dry the block with compressed air.
5. Lubricate the cylinder bores with clean engine oil in order to prevent rusting.
6. Inspect the engine block for the following conditions: Gasket surfaces for deep gouges or other damage Crankshaft bearing bores for wear The surfaces where the crankshaft bearings contact the crankshaft bearing bore must be smooth. All crankshaft bearing bores must be round and uniform in the inside diameter (ID) at all the bearing supports. If a crankshaft bearing cap is damaged and requires replacement, refer to «Crankshaft and Bearings Cleaning and Inspection»(ref-277941-S34536460262008012100000) . Camshaft bearing bores for wear or damage Valve lifter bores for scuffing or wear Engine block for cracks or other damage Cylinder walls for scoring or gouges Coolant jackets for cracks Crankshaft bearing webs for cracks Engine mount bosses for damage The oil passages for restrictions
7. Inspect the engine block cylinder head deck for flatness, using a straight edge and a feeler gage. The surface must be flat within 0.100 mm (0.004 in).
8. Using a bore gage, measure the cylinder bore for taper, out-of-round, and oversize. Slide the bore gage up and down throughout the length of the cylinder bore. Inspect the bore both parallel and perpendicular to the centerline of the crankshaft at the top, center, and bottom of the bore. A cylinder bore that measures 107.940-107.990 mm (4.249-4.251 in) may be serviced with a standard size piston/connecting rod assembly. A cylinder bore that exceeds the maximum diameter must be serviced with an oversized piston/connecting rod assembly.

Crankshaft and Bearings Cleaning and Inspection

Tools Required

1. J 7872 Magnetic Base Dial Indicator
2. J 43690 Rod Bearing Clearance Checking Tool
3. J 43690-100 Rod Bearing Clearance Checking Tool - Adapter Kit
4. J 45059 Angle Meter

Crankshaft Inspection

1. Clean the crankshaft in solvent. Remove all sludge or restrictions from the oil passages.
2. Dry the crankshaft and bearings with compressed air.
3. Inspect the crankshaft for the following conditions: Crankshaft journals (1) should be smooth with no evidence of scoring or damage Deep grooves (2) Scratches or uneven wear (3) Pitted surfaces (4) Wear or damage to the thrust journal surfaces Scoring or damage to the rear seal surface Restrictions to oil passages Damage to threaded bolt holes
4. Inspect the crankshaft pin for damage: Measure for proper installed height (a). Correct height should be 2.00-2.25 mm (0.078-0.088 in). Replace the crankshaft pin if it is damaged.
5. Inspect the reluctor wheels for cracked, bent, or broken teeth. Measure between the crankshaft shoulder and the front reluctor wheel (1). Measure the gap between the front and rear reluctor wheels (2). The maximum allowable gap is 0.15 mm (0.006 in).
6. Measure the crankshaft main journals and the crankpins for out-of-round and taper.
7. Using a suitable fixture, support the crankshaft.
8. Measure the crankshaft runout using the J 7872 . Crankshaft runout should not exceed 0.051 mm (0.002 in).
9. Inspect the crankshaft thrust wall surface (1) for wear and/or excessive runout (2). Refer to «Engine Mechanical Specifications»(ref-277941-S07562565932008012100000) .

Crankshaft and Connecting Rod Bearing Inspection

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

Crankshaft Balancer Cleaning and Inspection

1. Clean the crankshaft balancer in solvent.
2. Dry the crankshaft balancer with compressed air.
3. Inspect the crankshaft balancer for the following conditions: Damaged belt grooves (3) Debris in the belt grooves (3) Worn, grooved, or damaged hub seal surface (1) Minor imperfections on the hub seal surface may be removed with a polishing compound or fine grade of emery cloth. A 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 (2)
4. Repair or replace the crankshaft balancer, as necessary.

Engine Flywheel Cleaning and Inspection (Automatic Transmission)

1. Clean the flex plate in solvent.
2. Dry the flex plate with compressed air.
3. Inspect the flex plate for the following conditions: Stress cracks around the engine flex plate-to-torque converter mounting bolt hole locations (1) and/or engine flex plate-to-crankshaft (2, 3) IMPORTANT: Do not attempt to repair the welded areas that retain the ring gear to the flex plate. Install a new flex plate. Cracks at welded areas that retain the ring gear onto the flex plate (4) Damaged or missing ring gear teeth (5)

Engine Flywheel Cleaning and Inspection (Manual Transmission)

1. Clean the engine flywheel in solvent.
2. Dry the engine flywheel with compressed air.
3. Inspect the manual transmission engine flywheel for the following conditions: Pitted surface (1) Scoring or grooves (2) Rust or other surface damage (3) Damaged ring gear teeth (4) Loose or improperly positioned ring gear The ring gear has an interference fit onto the engine flywheel and should be positioned completely against the flange of the engine flywheel.

Piston, Connecting Rod, and Bearings Cleaning and Inspection

1. Clean the piston and pin (144), connecting rod (119), and cap (117) in solvent.
2. Dry the components with compressed air.
3. Clean the piston ring grooves with a suitable ring groove cleaning tool.
4. Clean the piston oil lubrication holes and slots.
5. Inspect the piston for the following conditions: Eroded areas (1) on the top of the piston Scuffed or damaged skirt (2) Cracks in the piston ring lands, the piston skirt, or the pin bosses Piston ring grooves for nicks, burrs, or other warpage which may cause the piston ring to bind
6. Inspect the piston pin for scoring, wear, or other damage.
7. Measure the piston ring-to-piston ring groove side clearance. Refer to «Engine Mechanical Specifications»(ref-277941-S07562565932008012100000) . Insert the 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 the piston ring side clearance with a feeler gage.
9. If the side clearance is too small, try another piston ring set. Refer to «Engine Mechanical Specifications»(ref-277941-S07562565932008012100000) .
10. If the proper piston ring-to-piston ring groove clearance cannot be achieved, replace the piston and pin assembly.
11. Inspect the connecting rod for an out-of-round bearing bore.
12. Inspect the connecting rod for twisting.
13. Inspect the 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 6.5 mm (0.25 in) above the ring travel. The ring must be square to the cylinder wall. Use a feeler gage in order to measure the end gap. Select another size ring set if the end gap exceeds specifications.

Camshaft and Bearings Cleaning and Inspection

1. Clean the camshaft in solvent.
2. Dry the camshaft with compressed air.
3. Inspect the camshaft retainer plate for damage.
4. Inspect the camshaft for the following conditions: Camshaft bearing journals (1) that are: Worn Scored Damaged Worn camshaft lobes (2) Damaged sprocket bolt threads (3) Damaged sprocket pin (206)
5. Measure the camshaft journals with a micrometer. Refer to «Engine Mechanical Specifications»(ref-277941-S07562565932008012100000) .
6. Measure for excessive camshaft runout, using the J 7872 . Mount the camshaft in a suitable fixture. Use the J 7872 in order to measure for a bent camshaft. Refer to «Engine Mechanical Specifications»(ref-277941-S07562565932008012100000) .
7. Replace the camshaft if runout exceeds specifications.
8. Inspect the camshaft bearings (1-5) for wear or damage.
9. Replace the camshaft bearings, if necessary. Refer to «Camshaft Bearing Removal»(ref-277941-S39698195352008012100000) and «Camshaft Bearing Installation»(ref-277941-S20329272342008012100000) .

Scheme 149

1. Assemble the tool handle (10), expanding driver (4-8), and washer (2 or 3).
2. Insert the J 33049 tool into the engine block end camshaft bearings.
3. Drive the end bearings into the bore.
4. Select the expanding driver (4-8) and washer (2 or 3) from the J 33049 .
5. Assemble the tool.
6. Insert the J 33049 tool through the front of the engine block and to the inner bearing bores.
7. Install the bearing onto the expanding driver.
8. Tighten the expander assembly nut until the tool is snug in the bearing.
9. Align the oil lubrication hole in the bearing with the oil galleries in the engine block.
10. Push the guide cone into the front camshaft bearing bore to align the tool.
11. Drive the bearing into the bore.

Timing Chain and Sprockets Cleaning and Inspection

1. Clean the camshaft timing components in solvent.
2. Dry the components with compressed air.
3. Inspect the camshaft timing chain for binding or wear.
4. Inspect the camshaft and crankshaft sprockets for the following conditions: Worn teeth (1) Damaged teeth (2) Chipped teeth (3) Uneven wear on one edge of the teeth Worn valleys between the sprocket teeth Crankshaft sprocket keyway for wear

Valve Rocker Arm and Push Rods Cleaning and Inspection

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

Valve Lifters and Guides Cleaning and Inspection

1. Dry the components with compressed air.
2. Inspect the valve lifters for the following conditions: A damaged, mis-positioned, or broken clip (1) A scored or worn pushrod socket (2) A severely scuffed or worn lifter body (3) If the valve lifter body shows scuffing or wear, inspect the engine block valve lifter bores for wear or damage. Flat spots on the roller (4) A loose pin (5) A plugged oil hole (6)
3. If flat spots are found on the lifters, inspect the corresponding lobe on the camshaft for damage.
4. Inspect the valve lifter guides for the following conditions: Excessive guide slot side wear Cracks Damage
5. Inspect the valve lifter guide retainer for the following conditions: Wear, damage, or stress cracking in the leg areas Wear or damage around the retainer bolt holes

Cylinder Head Cleaning and Inspection

Tools Required

1. J 8089 Carbon Removal Brush
2. J 9666 Valve Spring Tester
3. J 8001 Dial Indicator Set

Visual Inspection Procedure

Inspect the cylinder head for the following conditions

1. Damaged gasket surfaces
2. Damage to threaded bolt holes
3. Burnt or eroded areas in the combustion chamber
4. Cracks in the exhaust ports and combustion chambers
5. External cracks in the water chamber
6. Restrictions in the intake or exhaust passages
7. Restrictions in the cooling system passages

Valve Inspection Procedure

1. Inspect the valves for the following conditions: Burnt or damaged areas (1) Undersized valve margin (2) Bent stem (3) Scoring or other damage to the stem (4) Worn key groove (5) Worn stem tip (6)
2. Inspect the valve contact surface for the following conditions: Undersized margin (1) Pitted surface (2) Burnt or eroded areas (3) Acceptable edge, margin (4)
3. Valves with excessive damage must be replaced.

Valve Spring Inspection and Measurement

1. Inspect the valve springs for broken coils or coil ends.
2. Use the J 9666 in order to measure the valve spring force. Refer to «Engine Mechanical Specifications»(ref-277941-S07562565932008012100000) .
3. If the valve spring tension is low, use a shim to increase tension.
4. Inspect the valve spring tension again. A valve spring that does not meet specification must be replaced.

Inspecting Valve Spring Installed Height

1. Install the valve rotator (3), the valve (4), the valve spring cap (1), and the valve stem keys (5) into the cylinder head.
2. Using a snap gage or inside micrometer, measure the distance from the top of the valve rotator to the bottom of the valve spring cap. Refer to «Engine Mechanical Specifications»(ref-277941-S07562565932008012100000) for proper valve spring installed height specifications.
3. Install a valve spring seat shim if the valve spring installed height measurement is greater than the specification.
4. Measure the valve spring installed height again. Replace the cylinder head if the valve spring installed height cannot be obtained.

Oil Pump Cleaning and Inspection

1. Clean the oil pump components in cleaning solvent.
2. Dry the components with compressed air.
3. Inspect the gears (427, 428) for the following conditions: Scoring Chipping Galling Excessive wear
4. Inspect the oil pump housing (422) for the following conditions: Damaged bolt hole threads Worn oil pump driveshaft bore Scoring or excessive wear within the housing Worn driven gear shaft
5. Inspect for a collapsed pressure relief valve spring.
6. Inspect the pressure relief valve for scoring or wear. The valve should move freely within the bore of the housing.

Oil Pump Drive Cleaning and Inspection

1. Clean the oil pump drive in cleaning solvent.
2. Dry the oil pump drive with compressed air.
3. Inspect the oil pump drive (1) for the following conditions: Excessive play in the oil pump drive bearing Damage to the oil pump drive clamp bolt hole (2) Damaged gear (3) for the following conditions: Chipping Galling Wear Damage to the oil pump driveshaft tang
4. Damage to the oil pump drive body (4).
5. If the oil pump drive is to be used again, lubricate the bearing with clean engine oil and apply grease to all gear teeth (3).

Valve Rocker Arm Cover Cleaning and Inspection

1. Remove the white wiring harness clip locks.
2. Disconnect the ignition coil wiring harness from the ignition coils.
3. Remove the ignition coil wiring harness retainer bolts.
4. Open the 2 wiring harness retainers and remove the ignition coil wiring harness.
5. Remove the ignition coil bolts.
6. Remove the ignition coils.
7. Clean the valve rocker arm cover in solvent.
8. Dry the covers with compressed air.
9. Inspect the covers for the following conditions: Gouges or damage to the sealing surfaces Cracking or damage to the valve cover gasket Debris or damage to the bolt hole threads
10. Install the ignition coils.
11. Install the ignition coil bolts. Tighten: Tighten the ignition coil bolts to 12 N.m (106 lb in).
12. Install and secure the ignition coil wiring harness into the 2 wiring harness retainers.
13. Install the ignition coil wiring harness retainer bolts. Tighten: Tighten the ignition coil wiring harness retainer bolts to 12 N.m (106 lb in).
14. Connect the ignition coil wiring harness to the ignition coils. Ensure the connectors for cylinders 1 and 3, and cylinders 6 and 8 are connected to the corresponding ignition coils.
15. Install the white wiring harness clip locks.

Oil Pan Cleaning and Inspection

1. Remove the oil pan gasket (404) from the groove in the oil pan (400).
2. Clean the oil pan in solvent.
3. Dry the oil pan with compressed air.
4. Inspect the oil pan for the following conditions: The drain plug hole for damaged threads Gouges or damage to the oil pan sealing surfaces Cracks or damage to the exterior of the oil pan Damage to the oil level indicator tube area Damage to the oil pan gasket

Intake Manifold Cleaning and Inspection

1. Clean the intake manifold in an approved solvent. Clean debris out of all bolt holes. Clean the intake manifold gasket sealing surfaces. Clean all intake manifold ports.
2. Dry the intake manifold with compressed air.
3. Inspect the following components: The intake manifold bolt holes (1) for cracks and/or damage The manifold absolute pressure (MAP) sensor sealing surface (2) for damage The evaporative emission (EVAP) purge valve sealing surface (4) for damage The purge valve bolt has a sealer that may come off during removal of the bolt. Ensure all sealant is removed from the bolt hole. The intake manifold-to-cylinder head sealing surfaces (3) for damage The throttle body studs (5) for damage Replace, as necessary. The throttle body mounting surface (6) for damage The oil fill tube hole (7) for signs of leakage Seal, as necessary. Positive crankcase ventilation (PCV) port (8) for debris or varnish buildup

Exhaust Manifold Cleaning and Inspection

1. Clean the exhaust manifolds in solvent.
2. Dry the exhaust manifolds with compressed air.
3. Inspect the exhaust manifolds for the following conditions: Damage to the gasket sealing surfaces Damage to the exhaust manifold studs Broken or damaged heat shields Cracks in the exhaust manifold Restrictions within the exhaust passages
4. Measure the alignment, or surface flatness, of the exhaust manifold flanges, using a straight edge and a feeler gage. Exhaust manifold surface flatness must not exceed 0.254 mm (0.01 in).
5. If the surface flatness is not within specifications, the exhaust manifold is warped and must be replaced.

Inspection Procedure

1. Inspect the engine coolant crossover (308) for the following conditions: Corrosion or damage to the gasket sealing surfaces Corrosion or damage to the thermostat bypass hose fitting Corrosion or damage to the heater hose fitting Corrosion or damage to the threads of the water outlet
2. Inspect the water outlet (311) for corrosion or damage.

Water Pump Cleaning and Inspection

1. Inspect the water pump pulley for damage at the belt contact area (1) and the pulley-to-water pump mounting surface.
2. Clean all excess dirt and debris from the water pump housing.
3. Inspect the water pump for the following conditions: Leakage at the hose fitting (1) Leakage at the water pump weep hole (3) A stain around the weep hole is acceptable. If leakage occurs, dripping with the engine running and the cooling system pressurized, replace the water pump. Gasket sealing surfaces (2) for excessive scratches or gouging Restrictions within the internal coolant passages (6) Excessive side-to-side play in the pulley shaft If the shaft end play exceeds 0.381 mm (0.015 in), replace the water pump. Rotate the pump shaft by hand and inspect for operation roughness. If the hub wobbles, is noisy, or feels rough when rotated, replace the water pump. The shaft and fan hub must turn straight and smoothly. Damage to threaded bolt holes (4) Damage to the fan clutch mounting threads (5)

Scheme 150

The thread repair process involves a solid, thin walled, self-locking, carbon steel, bushing type insert (1). During the bushing installation process, the driver tool expands the bottom external threads of the insert into the base material (2). This action mechanically locks the insert in place. Also, when installed to the proper depth, the flange of the insert will be seated against the counterbore of the repaired hole.

1. Drill out the threads of the damaged hole (1). M6 inserts require a minimum drill depth of 15 mm (0.59 in). M8 inserts require a minimum drill depth of 20 mm (0.79 in). M10 inserts require a minimum drill depth of 23.5 mm (0.93 in).
2. Using compressed air, clean out any chips.
3. Counterbore the hole to the full depth permitted by the tool (1).
4. Using compressed air, clean out any chips.
5. Using a tap wrench (2), tap the threads of the drilled hole. M6 inserts require a minimum tap depth of 15 mm (0.59 in). M8 inserts require a minimum tap depth of 20 mm (0.79 in). M10 inserts require a minimum tap depth of 23.5 mm (0.93 in).
6. Using compressed air, clean out any chips.
7. Spray cleaner GM P/N 12346139, GM P/N 12377981 (Canadian P/N 10953463), or equivalent, into the hole.
8. Using compressed air, clean any cutting oil and chips out of the hole.
9. Lubricate the threads of the installer tool (2) with the driver oil (1).
10. Install the insert (2) onto the driver tool (1).
11. Apply threadlock LOCTITE™ 277, J 42385-109 (1), or equivalent, to the insert OD threads (2).
12. Install the insert (2) into the hole. Install the insert until the flange of the insert contacts the counterbored surface. Continue to rotate the installer tool (1) through the insert. The installer tool will tighten up before screwing completely through the insert. This is acceptable. You are forming the bottom threads of the insert and mechanically locking the insert to the base material threads.
13. Inspect the insert for proper installation into the hole. A properly installed insert (1) will be either flush or slightly below flush with the surface of the base material (2).

Engine Mechanical Diagnostic Procedure Revisions

All diagnosis on a vehicle should follow a logical process. Strategy based diagnostics is a uniform approach for repairing all systems. The diagnostic flow may always be used in order to resolve a system condition. The diagnostic flow is the place to start when repairs are necessary. For a detailed explanation, refer to Strategy Based Diagnosis or Diagnostic Starting Point - Engine Mechanical .