Engine Mechanical - 8.1L: Diagnosis Chevrolet Silverado 1500

Diagnostic Starting Point - Engine Mechanical

Begin the system diagnosis by reviewing the Disassembled Views , Engine Component Description , Lubrication Description , New Product Information , and the Drive Belt System Description . 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-238177-S28692454672006072400000) in Vehicle DTC Information 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-238225-S14467675652006072400000) , «Engine Component Description»(ref-238225-S29120562462006072400000) , «Drive Belt System Description»(ref-238225-S02571596582006072400000) , «Lubrication Description»(ref-238225-S16111645122006072400000) and «New Product Information»(ref-238225-S15869155042006072400000) .

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 problem. The diagnostic flow is the place to start when repairs are necessary. For a detailed explanation, refer to Strategy Based Diagnosis in General Information.

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the Engine. Refer to «Checking Aftermarket Accessories»(ref-238178-S36192588272006072400000) in Wiring Systems.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
3. Check for the correct oil level, proper oil viscosity, and correct filter application.
4. Verify the exact operating conditions under which the concern 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 make sure 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-238225-S03581940832006072400000)
2. «Base Engine Misfire with Abnormal Internal Lower Engine Noises»(ref-238225-S15370429652006072400000)
3. «Base Engine Misfire with Abnormal Valve Train Noise»(ref-238225-S02046971082006072400000)
4. «Base Engine Misfire with Coolant Consumption»(ref-238225-S06553492112006072400000)
5. «Base Engine Misfire with Excessive Oil Consumption»(ref-238225-S07786498072006072400000)
6. «Engine Noise on Start-Up, but Only Lasting a Few Seconds»(ref-238225-S32183324062006072400000)
7. «Upper Engine Noise, Regardless of Engine Speed»(ref-238225-S00113401982006072400000)
8. «Lower Engine Noise, Regardless of Engine Speed»(ref-238225-S24051636472006072400000)
9. «Engine Noise Under Load»(ref-238225-S22413521832006072400000)
10. «Engine Will Not Crank - Crankshaft Will Not Rotate»(ref-238225-S37492548852006072400000)
11. «Coolant in Combustion Chamber»(ref-238225-S16884818412006072400000)
12. «Coolant in Engine Oil»(ref-238225-S15983958882006072400000)
13. «Engine Compression Test»(ref-238225-S32935585872006072400000)
14. «Cylinder Leakage Test»(ref-238225-S33051909632006072400000)
15. «Oil Consumption Diagnosis»(ref-238225-S02621641592006072400000)
16. «Oil Pressure Diagnosis and Testing»(ref-238225-S36704709802006072400000)
17. «Drive Belt Chirping Diagnosis»(ref-238225-S07250762942006072400000)
18. «Drive Belt Squeal Diagnosis»(ref-238225-S21713300942006072400000)
19. «Drive Belt Whine Diagnosis»(ref-238225-S11616353302006072400000)
20. «Drive Belt Rumbling Diagnosis»(ref-238225-S10578610602006072400000)
21. «Drive Belt Vibration Diagnosis»(ref-238225-S19563310582006072400000)
22. «Drive Belt Falls Off Diagnosis»(ref-238225-S02766369292006072400000)
23. «Drive Belt Excessive Wear Diagnosis»(ref-238225-S01341962182006072400000)

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 the 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 gauge at zero. Then crank the engine through four compression strokes (four puffs).
7. Make the compression check the same for each cylinder. Record the reading. The minimum compression in any one 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 one cylinder is 1035 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 (one 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 two 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 two cylinders.

Oil Consumption Diagnosis

Excessive oil consumption, not due to leaks, is the use of more 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 more 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 oil level indicator. With the vehicle on a level surface, allow adequate drain down time and check 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 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 rings to seat. 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. Too high an oil level will cause aeration within the oil. 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.
2. Operate the engine and verify low or no oil pressure on the vehicle oil pressure gage or oil indicator light. Listen for a noisy valve train or knocking noise.
3. Inspect for the following: 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
4. Remove the oil pressure gage sensor or another engine block oil gallery plug.
5. Install an oil pressure gage and measure the engine oil pressure.
6. If the engine oil pressure is below specifications, inspect the engine for one or more of the following: 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

The chirping noise may be intermittent due to moisture on the drive belt(s) or the accessory drive pulley(s). In order to duplicate the customers concern, it may be necessary to spray a small amount of water onto the drive belt(s). If spraying water onto the drive belt(s) duplicates the symptom, cleaning the accessory drive pulley(s) may be the most probable solution.

A loose or improper installation of a body or suspension component, or other item(s) on the vehicle may also cause the chirping noise.

A loose or improper installation of a body, or suspension component, or other item(s) on the vehicle may cause the squeal noise.

If the squeal noise is intermittent, verify that it is not the accessory drive component(s) by varying their load(s) making sure they are operating to their maximum capacity. An overcharged air conditioning (A/C) system, a power steering system restriction or the incorrect fluid, or a failing generator are suggested items to inspect.

The drive belt(s) will not cause the whine.

If the whine is intermittent, verify that it is not the accessory drive component(s) by varying their loads, making sure they are operating to their maximum capacity. An overcharged air conditioning (A/C) system, a power steering system restriction or the incorrect fluid, or a failing generator are suggested items to inspect.

Vibration from the engine operating may cause a body component or another part of the vehicle to make rumbling noise.

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

If after replacing the drive belt(s) and completing the diagnostic table, the rumbling is only heard with the drive belt(s) installed, there might be an accessory drive component failure. Varying the load on the different accessory drive component(s) may aid in identifying which component is causing the rumbling noise.

The accessory drive components may have an affect on engine vibration. An overcharged air conditioning (A/C) system, a power steering system restriction, 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.

If the drive belt(s) repeatedly falls off the accessory drive pulley(s), this may be caused by a pulley misalignment.

An extra load that is quickly applied or released by an accessory drive component may cause the drive belt(s) to fall off. Verify that the accessory drive component(s) are operating properly.

If the drive belt(s) is the incorrect length, the drive belt tensioner(s) may not maintain the proper tension on the drive belt(s).

Excessive wear on a drive belt(s) is usually caused by incorrect installation or the incorrect drive belt(s) for the application.

Minor misalignment of the accessory drive pulley(s) will not cause excessive wear, but will probably cause the drive belt(s) to make a noise or fall off.

Excessive misalignment of the accessory drive pulley(s) will cause excessive wear and may also make the drive belt(s) fall off.

Drive Belt Tensioner Diagnosis

1. Remove the drive belt(s). Refer to «Drive Belt Replacement - Accessory»(ref-238225-S30832365212006072400000) or «Drive Belt Replacement - Air Conditioning»(ref-238225-S29324271352006072400000) .
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-238225-S36425538632006072400000) or «Drive Belt Tensioner Replacement - Air Conditioning»(ref-238225-S22323884382006072400000) .
5. Install the drive belt(s). Refer to «Drive Belt Replacement - Accessory»(ref-238225-S30832365212006072400000) or «Drive Belt Replacement - Air Conditioning»(ref-238225-S29324271352006072400000) .

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-238222-S27810710062006072400000) 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 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 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-238225-S05200931462006072400000) . 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. Use a bore gage and 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. Check 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 between 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. Measure the crankshaft runout using J 7872 . Crankshaft runout should not exceed 0.051 mm (0.002 in).
8. Inspect the crankshaft thrust wall surface (1) for wear and/or excessive runout (2). Refer to «Engine Mechanical Specifications»(ref-238225-S16999722612006072400000) .

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: 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 flexplate in solvent.
2. Dry the flexplate with compressed air.
3. Inspect the flexplate for the following conditions: Stress cracks around the engine flexplate-to-torque converter mounting bolt hole locations (1) and/or engine flexplate-to-crankshaft (2, 3) IMPORTANT: Do not attempt to repair the welded areas that retain the ring gear to the flexplate plate. Install a new flexplate. Cracks at welded areas that retain the ring gear onto the flexplate (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-238225-S16999722612006072400000) . 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-238225-S16999722612006072400000) .
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.

Scheme 276

Scheme 277

Scheme 278

1. Assemble the right bank pistons and connecting rods with the arrow (1) on the top of the piston facing front of engine and the master or larger flange (2) of the connecting rod facing rear of engine.
2. Assemble the left bank pistons and connecting rods with the arrow (1) on the top of the piston facing front of engine and the master or larger flange (2) of the connecting rod facing front of engine.
3. Install the retainer. The retainer should be seated in the groove of the pin bore.
4. Lubricate the pin and pin bore with clean engine oil.
5. Install the piston pin to the piston and connecting rod.
6. Install the retainer. The retainer should be seated in the groove of the pin bore. Ensure the pin moves freely within the piston pin bore.
7. Using piston ring pliers, install the piston rings onto the piston.
8. Install the lower oil control piston ring spacer onto the piston.
9. Install the lower oil control piston ring onto the piston (1).
10. Install the upper oil control piston ring onto the piston (1).
11. Position the oil control piston ring end gaps a minimum of 90 degrees apart (1, 2, 3).
12. Install the lower compression piston ring onto the piston. The mark (1) on the side of the piston ring should face the top of the piston.
13. Install the upper compression piston ring onto the piston. The mark (1) on the side of the piston ring should face the top of the piston.
14. Position the compression ring end gaps 120 degrees apart.
15. Install the connecting rod bearings (118) to the rod (119) and cap (117).

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 it rolls smoothly, it is OK. 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 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 the rocker arm studs for the following conditions: Damaged threads (1) Excessive wear or damage (2) 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 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: A damaged, mispositioned 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 lifter(s), inspect the corresponding lobe on the camshaft for damage.
4. Inspect the valve lifter guides for the following: Excessive guide slot side wear Cracks or damage
5. Inspect the valve lifter guide retainer for the following: 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-238225-S16999722612006072400000) .
3. If the valve spring tension is low, use a shim to increase tension.
4. Recheck the valve spring tension, a valve spring that does not meet specification must be replaced.

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: Scoring Chipping Galling Excessive wear
4. Inspect the oil pump housing (422) for the following: 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: Chipping Galling Wear Damage to the oil pump drive shaft tang
4. Damage to the oil pump drive body (4).
5. If the oil pump drive is to be reused, 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: 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, making sure 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 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: 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. Reseal 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 components with compressed air.
3. Inspect the exhaust manifolds for the following: 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: 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: 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 roughness of operation 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)

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 problem. The diagnostic flow is the place to start when repairs are necessary. For a detailed explanation, refer to Strategy Based Diagnosis in General Information or Diagnostic Starting Point - Engine Mechanical in Engine Mechanical.