Engine Mechanical - 4.3L: Diagnosis Chevrolet Silverado Classic 1500

Diagnostic Starting Point - Engine Mechanical

Begin the system diagnosis by reviewing the Disassembled Views , Engine Component Description , Lubrication Description , New Product Information and 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 the «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-277938-S42060090482008012100000) , «Engine Component Description»(ref-277938-S14051644982008012100000) , «Lubrication Description»(ref-277938-S18501648482008012100000) , «New Product Information»(ref-277938-S42538074692008012100000) and «Drive Belt System Description»(ref-277938-S36664467242008012100000) .

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 .

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. 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-277938-S37057930872008012100000)
2. «Base Engine Misfire with Abnormal Internal Lower Engine Noises»(ref-277938-S14793094942008012100000)
3. «Base Engine Misfire with Abnormal Valve Train Noise»(ref-277938-S24183829062008012100000)
4. «Base Engine Misfire with Coolant Consumption»(ref-277938-S03911827682008012100000)
5. «Base Engine Misfire with Excessive Oil Consumption»(ref-277938-S12703803152008012100000)
6. «Engine Noise on Start-Up, but Only Lasting a Few Seconds»(ref-277938-S29004237162008012100000)
7. «Upper Engine Noise, Regardless of Engine Speed»(ref-277938-S07473052172008012100000)
8. «Lower Engine Noise, Regardless of Engine Speed»(ref-277938-S09341417962008012100000)
9. «Engine Noise Under Load»(ref-277938-S07863390372008012100000)
10. «Engine Will Not Crank - Crankshaft Will Not Rotate»(ref-277938-S01188347582008012100000)
11. «Engine Compression Test»(ref-277938-S38057148262008012100000)
12. «Oil Consumption Diagnosis»(ref-277938-S11142204002008012100000)
13. «Oil Pressure Diagnosis and Testing»(ref-277938-S21302316402008012100000)
14. «Oil Leak Diagnosis»(ref-277938-S38078615082008012100000)
15. «Drive Belt Chirping, Squeal, and Whine Diagnosis»(ref-277938-S32766837932008012100000)
16. «Drive Belt Rumbling and Vibration Diagnosis»(ref-277938-S31239695982008012100000)
17. «Drive Belt Falls Off and Excessive Wear Diagnosis»(ref-277938-S19078981202008012100000)
18. «Drive Belt Tensioner Diagnosis»(ref-277938-S29429066902008012100000)

Engine Compression Test

1. Ensure that the vehicle batteries are in good condition, and fully charged.
2. Operate the vehicle until the engine is at normal operating temperature.
3. Disconnect the positive ignition coil wire plug from the ignition coil.
4. Disconnect the fuel injector electrical connector.
5. Remove all of the spark plugs.
6. Block the throttle linkage wide open.
7. Install the engine cylinder compression gage to the cylinder being tested.
8. Using the vehicle starter motor, rotate, or crank the engine for 4 compression strokes, or puffs, for the cylinder being tested. If the engine rotates for more than 4 compression strokes, test the cylinder again.
9. Record the compression reading.
10. Remove the engine cylinder compression gage from the cylinder being tested.
11. Repeat steps 8-11 for each additional cylinder. All cylinders must be tested to obtain valid test results.
12. If any cylinders have low compression, inject approximately 15 ml (1 oz) of engine oil into the cylinder through the spark plug hole.
13. Repeat steps 8-11 for all low compression cylinders.
14. 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). Multiply the highest cylinder pressure by 70 percent, 1035 kPa x 70 percent = 725 kPa (150 psi x 70 percent = 105 psi), in order to determine the lowest allowable pressure in any other cylinder. Normal The compression builds up quickly and evenly to the specified compression. Piston rings leaking Compression is low on the first compression stroke. The compression builds up on the following strokes, but does not reach normal. Compression improves considerably when you add oil. Valves leaking Compression is low on the first compression stroke. The compression does not build up on the following strokes, and does not reach normal. Compression does not improve much, if at all, when you add oil. Head gasket leaking Compression is low on the first stroke. The compression does not build up on the following strokes, and does not reach normal. Compression does not improve much, if at all, when you add oil. Adjacent cylinders have the same, or similar, low compression readings.
15. If one or more cylinders fails to meet the minimum specified compression, repair or replace all damaged or worn components and test the engine again.

Cylinder Leakage Test

With the use of air pressure, a cylinder leakage test will aid in the diagnosis. Use the cylinder leakage test in conjunction with the engine compression test in order to isolate the cause of leaking cylinders.

1. Disconnect the battery ground negative cable.
2. Remove the spark plugs. Refer to «Spark Plug Replacement»(ref-277873-S32460422202008012100000) use for the 4.3L engine.
3. Rotate the crankshaft to place the piston in the cylinder being tested at top dead center (TDC) of the compression stroke, with both valves closed.
4. Install the J 35667-A . See «Special Tools»(ref-277938-S12463979202008012100000) .
5. Apply shop air pressure to the J 35667-A and adjust according to the manufacturer instructions. See «Special Tools»(ref-277938-S12463979202008012100000) .
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 from the intake or exhaust system may indicate a worn or burnt valve or a broken valve spring. Remove the valve rocker arm cover of the suspect cylinder head. Refer to «Valve Rocker Arm Cover Replacement - Left Side»(ref-277938-S20911449062008012100000) or «Valve Rocker Arm Cover Replacement - Right Side»(ref-277938-S21491217102008012100000) Ensure that both valves are closed. Inspect the cylinder head for a broken valve spring. Remove and inspect the suspect cylinder head. Refer to «Cylinder Head Replacement - Left Side»(ref-277938-S37280722942008012100000) or «Cylinder Head Replacement - Right Side»(ref-277938-S12003992052008012100000) . Air leakage from the crankcase, oil level indicator, or oil fill tube may indicate worn piston rings, a damaged piston, a worn or scored cylinder bore, a damaged engine block or a damaged cylinder head. Remove the piston from the suspect cylinder. Refer to «Piston, Connecting Rod, and Bearing Removal»(ref-277938-S12485614622008012100000) or «Piston, Connecting Rod, and Bearing Installation»(ref-277938-S10814677352008012100000) . Inspect the piston and connecting rod assembly. Refer to «Piston, Connecting Rod, and Bearings Cleaning and Inspection»(ref-277938-S21218988442008012100000) . Inspect the engine block. Refer to «Engine Block Cleaning and Inspection»(ref-277938-S27029236282008012100000) . Inspect the cylinder head. Refer to «Cylinder Head Cleaning and Inspection»(ref-277938-S26138348812008012100000) . Air bubbles in the cooling system may indicate a damaged cylinder head or a damaged cylinder head gasket. Remove both cylinder heads. Refer to «Cylinder Head Replacement - Left Side»(ref-277938-S37280722942008012100000) or «Cylinder Head Replacement - Right Side»(ref-277938-S12003992052008012100000) . Inspect both cylinder heads. Refer to «Cylinder Head Cleaning and Inspection»(ref-277938-S26138348812008012100000) . Inspect the engine block. Refer to «Engine Block Cleaning and Inspection»(ref-277938-S27029236282008012100000) .
7. Remove the J 35667-A . See «Special Tools»(ref-277938-S12463979202008012100000) .
8. Install the spark plugs. Refer to «Spark Plug Replacement»(ref-277873-S32460422202008012100000) use for the 4.3L engine.
9. Connect the battery ground negative cable.

Oil Consumption Diagnosis

Excessive oil consumption, not due to leaks, is the use of 1 liter (1 quart) of engine oil within 3 200 kilometers (2,000 miles). However, during initial engine break-in periods 4 828-6 437 kilometers (3,000-4,000 miles), oil consumption may exceed 1 liter (1 quart) or more. The causes of excessive oil consumption include the following conditions

1. External oil leaks Tighten the 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, damaged, or the seal omitted Ream the valve 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 piston rings to seat. Replace broken or worn piston rings as necessary.
8. Piston improperly installed or miss-fitted

Oil Pressure Diagnosis and Testing

1. With the vehicle on a level surface, allow adequate drain down time, 2-3 minutes, and measure for a low engine oil level. Add the recommended grade engine oil, 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 the oil indicator light. Listen for a noisy valve train or a 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.
6. Start the engine and then allow the engine to reach normal operation temperature.
7. Measure the engine oil pressure at the following RPM: Specification: 42 kPa (6 psig) minimum, at 1,000 RPM 125 kPa (18 psig) minimum, at 2,000 RPM 166 kPa (24 psig) minimum, at 4,000 RPM
8. If the engine oil pressure is below minimum 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 Cracked, porous or restricted oil galleries Engine block oil gallery plugs missing or incorrectly installed Broken valve lifters

Oil Leak Diagnosis

Oil Leak Diagnosis

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.

Engine Mount Inspection

Note. Refer to Engine Mounting Notice .

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-277851-S21776392712008012100000) .
2. Inspect for loose or missing bolts at the following locations: Engine mount bracket to engine Engine mount frame bracket to frame Engine mount to engine mount bracket Engine mount to engine mount frame bracket
3. Replace missing or loose bolts.
4. In order to access the square tab on the right side of the engine remove the starter. Refer to «Starter Motor Replacement (4.3L Engine)»(ref-277854-S36909298662008012100000) .
5. Using a jack on the square tab at the rear of the engine block (left side shown) raise the engine in order to complete the following tasks: Remove weight from the engine mount. Place a slight tension on the rubber cushion. Observe the engine mount while raising the engine.
6. Replace the engine mount if the following conditions exist: Heat check cracks cover the hard rubber surface. The rubber cushion is separated from the metal plate of the engine mount. There is a split through the rubber cushion.
7. Install the starter, if removed. Refer to «Starter Motor Replacement (4.3L Engine)»(ref-277854-S36909298662008012100000) .

Engine Block Cleaning and Inspection

1. Clean all the remaining sealing or gasket material from the sealing surfaces.
2. Clean the engine block with cleaning solvent.
3. Flush the engine block with clean water or steam.
4. Clean the cylinder bores.
5. Clean the oil galleries and the oil passages.
6. Clean the scale and the deposits from the coolant passages.
7. Clean the engine block cylinder head bolt holes.
8. After cleaning the engine block, spray or wipe the cylinder bores and the machined surfaces with clean engine oil.
9. Inspect the following areas: Coolant jackets (1) for cracks Cylinder bores (2) for scratches or gouging Valve lifter bores (3) for excessive scoring or wear Threaded holes (4) for damage Crankshaft bearing webs (5) for cracks Crankshaft bearing caps (6) and the crankshaft bearing bores (7) for damage The crankshaft bearing bores should be round and uniform when measuring the inside diameter (ID). The surface where the crankshaft bearings contact the crankshaft bearing bore should be smooth. If a crankshaft bearing cap is damaged and requires replacement, replace the crankshaft bearing cap first, then rebore the engine block crankshaft bearing bores and check for the proper alignment. Finally, check the crankshaft for the proper clearances. Engine block core hole plug bores (8) for damage Engine block (9) for cracks or damage Engine mount bosses (10) for damage
10. Measure the cylinder bores for taper and out-of-round. Depress the plunger on the J 8087 to 7 mm (0.275 in) or until the J 8087 enters the cylinder bore. Center the J 8087 in the cylinder bore and turn the indicator dial to 0. Move the J 8087 up and down the cylinder bore to determine the cylinder bore taper. Refer to «Engine Mechanical Specifications»(ref-277938-S01556385892008012100000) . Turn the J 8087 to different points around the cylinder bore to determine the cylinder bore out-of-round condition. Refer to «Engine Mechanical Specifications»(ref-277938-S01556385892008012100000) .

Piston, Connecting Rod, and Bearings Cleaning and Inspection

1. Clean the piston and connecting rod 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: Eroded areas (1) on the top of the piston Scuffed or damaged skirt (2) Damage to the pin bore (3) 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. 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 gauge.
9. If the 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. To determine the proper piston ring side clearance, refer to «Engine Mechanical Specifications»(ref-277938-S01556385892008012100000) .
12. Inspect the connecting rod for an out-of-round bearing bore. Refer to «Engine Mechanical Specifications»(ref-277938-S01556385892008012100000) .
13. Inspect the connecting rod for twisting.
14. Inspect the connecting rod for damage to the bearing cap and bolt threads.
15. Measure the piston compression ring end gap. IMPORTANT: Fit each compression ring to the cylinder in which it will be used. 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. Refer to «Engine Mechanical Specifications»(ref-277938-S01556385892008012100000) .

Crankshaft and Bearings Cleaning and Inspection

Tools Required

1. J 7872 Magnetic Base Dial Indicator
2. J 43690 Rod Bearing Clearance Checking Tool. See «Special Tools»(ref-277938-S12463979202008012100000) .
3. J 45059 Angle Meter. See «Special Tools»(ref-277938-S12463979202008012100000) .

1. Clean the crankshaft in cleaning solvent. Remove all sludge or restrictions from the oil passages.
2. Dry the crankshaft with compressed air.
3. Clean the crankshaft bearings in cleaning solvent. Wipe the crankshaft bearings clean with a soft cloth, do not scratch the crankshaft bearing surfaces.
4. Dry the crankshaft bearings with compressed air.
5. Inspect the crankshaft for the following: 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 the oil passages Damage to the threaded bolt holes
6. Inspect the crankshaft balancer key (1), the keyway (2), and the threaded hole (3) for damage. Repair or replace the crankshaft as necessary.
7. Measure the crankpins for out-of-round and taper. Refer to «Engine Mechanical Specifications»(ref-277938-S01556385892008012100000) .
8. Use a suitable support to support the crankshaft on the front and rear journals.
9. Use the J 7872 in order to measure the crankshaft journal runout. The proper crankshaft journal runout is 0.025 mm maximum (0.0010 in maximum).
10. Measure the crankshaft end play. IMPORTANT: In order to properly measure the crankshaft end play, the crankshaft, the crankshaft bearings, the crankshaft bearing caps, and the crankshaft bearing cap bolts must be installed into the engine block and the bolts tightened using J 45059 . See «Special Tools»(ref-277938-S12463979202008012100000) . The proper crankshaft bearing cap bolt tightening specification first pass is 20 N.m (15 lb ft), final pass is 73 degrees. Firmly thrust the crankshaft first rearward, then forward. This will align the crankshaft rear bearings and the crankshaft thrust surfaces. With the crankshaft pushed forward, insert a feeler gage between the crankshaft and the crankshaft bearing surface and then measure the clearance. The proper crankshaft end play clearance specification is 0.050-0.20 mm (0.002-0.008 in). Turn the crankshaft to check for binding. If the crankshaft does not turn freely, then loosen the crankshaft bearing cap bolts, one crankshaft bearing cap at a time, until the tight crankshaft bearing is located. Burrs on the crankshaft bearing cap or engine block, foreign matter between the crankshaft bearing and the crankshaft bearing cap or the engine block, or a faulty crankshaft bearing could cause a lack of clearance between the crankshaft and crankshaft bearing.
11. Inspect the crankshaft bearings for craters or pockets. Flattened sections on the crankshaft bearing halves also indicate fatigue.
12. Inspect the crankshaft bearings for excessive scoring or discoloration.
13. Inspect the crankshaft bearings for dirt or debris imbedded into the crankshaft bearing material.
14. Inspect the crankshaft bearings for improper seating indicated by bright, polished sections of the crankshaft bearings. If the lower half of the crankshaft bearing is worn or damaged, both the upper and lower halves of the crankshaft bearing should be replaced. Generally, if the lower half of the crankshaft bearing is suitable for use, the upper half of the crankshaft bearing should also be suitable for use.

Crankshaft Balancer Cleaning and Inspection

1. Clean the crankshaft balancer in cleaning solvent.
2. Dry the crankshaft balancer with compressed air.
3. Inspect the crankshaft balancer for the following: Loose or improperly installed crankshaft balancer front groove pin (1) A properly installed front groove pin should be installed until flush or below flush with the face of the crankshaft balancer. IMPORTANT: A crankshaft front oil sealing surface with excessive scoring, grooves, rust, or other damage must be replaced. Worn, grooved, or damaged crankshaft front oil sealing surface (2) Minor imperfections on the crankshaft balancer crankshaft front oil seal surface may be removed with a polishing compound or fine grade emery cloth. Worn, chunking, or deteriorated rubber (3) between the hub and the outer ring Worn or damaged keyway (4) Worn or damaged bolt hole threads (5)

Engine Flywheel Cleaning and Inspection

1. Clean the engine flywheel (1 or 2) in cleaning solvent.
2. Dry the engine flywheel with compressed air.
3. Inspect the engine flywheel, automatic transmission, if equipped, for the following: Stress cracks around the engine flywheel-to-torque converter bolt hole locations (1) Missing balance weights Stress cracks around the engine flywheel-to-crankshaft bolt hole locations (2 or 3) Welded areas that retain the ring gear onto the engine flywheel for cracking (4), if present Damaged ring gear teeth (5)
4. Inspect the engine flywheel, manual transmission, if equipped, for loose or improperly installed flywheel weights, if applicable. A properly installed flywheel weight should be installed until flush or below flush with the face of the engine flywheel.
5. Inspect the engine flywheel, manual transmission, if equipped, for the following: Pitted friction 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 the ring gear should be positioned completely flat against the flange of the engine flywheel.

Camshaft and Bearings Cleaning and Inspection

1. Clean the engine camshaft in cleaning solvent.
2. Dry the engine camshaft with compressed air.
3. Inspect the camshaft retainer plate for damage. If the camshaft retainer plate is damaged, replace as necessary.
4. Inspect the camshaft bearings for correct fit into the engine block camshaft bearing bores. The camshaft bearings have an interference fit to the engine block camshaft bearing bores and must not be loose in the engine block camshaft bearing bores.
5. Inspect the camshaft bearings for excessive wear or scoring.
6. Inspect the engine camshaft for the following: Worn, scored, or damaged bearing journals (1) Worn engine camshaft lobes (2) Damaged bolt hole threads (3) Damaged camshaft sprocket locator pin (4)
7. Measure the engine camshaft journals with a micrometer. If the camshaft journals are more than 0.025 mm (0.0010 in) out-of-round, then replace the engine camshaft.
8. Measure for a bent engine camshaft or excessive engine camshaft runout using the J 7872 . Mount the engine camshaft in a suitable stand between centers. Use the J 7872 in order to check the intermediate engine camshaft journals. If the runout exceeds 0.065 mm (0.0026 in), the engine camshaft is bent and must be replaced.
9. Measure the engine camshaft lobe lift using the J 7872 . Place the engine camshaft on the V-blocks. Use the J 7872 in order to measure the engine camshaft lobe lift.
10. Replace the engine camshaft if the engine camshaft lobe lift is not within specifications. Refer to «Engine Mechanical Specifications»(ref-277938-S01556385892008012100000) .

Balance Shaft Cleaning and Inspection

1. Clean the following components in cleaning solvent: The balance shaft (1) The balance shaft retainer (2) The balance shaft rear bearing The balance shaft driven gear (4) The balance shaft drive gear
2. Dry the following components with compressed air: The balance shaft (1) The balance shaft retainer (2) The balance shaft rear bearing The balance shaft driven gear (4) The balance shaft drive gear
3. Inspect the balance shaft bearings for the following: Front ball bearing for damage or wear Front ball bearing for smoothness of operation Rear sleeve bearing for wear, scoring, or other damage
4. Inspect the balance shaft (1) for the following: Wear or scoring on the rear bearing journal Damaged bolt hole threads Damage to the balance shaft driven gear locator pin
5. Inspect the balance shaft retainer (2) for wear or damage.
6. Inspect the balance shaft retainer bolts (3) for damaged threads.
7. Inspect the driven gear (4) for the following: Excessive wear or damage Nicks, burrs, or scoring
8. Inspect the driven gear bolt (5) for damaged threads.
9. Inspect the balance shaft drive gear for the following: Excessive wear or damage Nicks, burrs, or scoring

Timing Chain and Sprockets Cleaning and Inspection

1. Clean the components with cleaning solvent.
2. Dry the components with compressed air.
3. Inspect the camshaft timing chain for binding or wear.
4. Inspect the camshaft sprocket and the crankshaft sprocket for: Broken teeth (1) Damaged teeth (2) Chipped teeth (3) Worn teeth Uneven wear on the edge of the teeth Worn valleys between the sprocket teeth Crankshaft sprocket keyway for wear
5. Inspect the timing chain tensioner bracket and shoe for cracking and wear.

Valve Rocker Arm and Push Rods Cleaning and Inspection

1. Mark, sort, and organize the components for assembly.
2. Clean the components with cleaning solvent.
3. Dry the components with compressed air.
4. Inspect the valve rocker arm components for the following: Valve rocker arm valve pushrod socket contact surface (1) The contact surface must be smooth with no scoring or excessive wear. Valve rocker arm roller pivot for binding or damage (2) Valve rocker arm valve stem contact surface (3) The contact surface should be smooth with no scoring or excessive wear. Valve rocker arm bolt threads for damage (4)
5. Inspect the valve pushrods for the following: Restriction of the oil passage (1) Wear or scoring of the end contact surfaces (2) The end contact surfaces must be smooth with no scoring or excessive wear. Shaft for bends (3) Roll the valve pushrod on a flat surface to determine if the valve pushrod is bent.
6. Inspect the valve rocker support for excessive wear or damage.

Valve Lifters and Guides Cleaning and Inspection

1. Mark, sort, and organize the components for assembly.
2. Clean the components in cleaning solvent.
3. Dry the components with compressed air.
4. Inspect the valve lifter pushrod guides for excessive wear.
5. Inspect the valve lifter pushrod guides for cracks or damage.
6. Inspect the valve lifter for the following: Broken or damaged clip (1) Worn pushrod socket (2) Scuffed or worn lifter body (3) If the valve lifter shows scuffing or wear, inspect the engine block valve lifter bores for wear. Worn roller (4) Loose or damaged pin (5) Plugged oil hole (6)

Cylinder Head Cleaning and Inspection

Tools Required

1. J 8001 Dial Indicator Set
2. J 8089 Carbon Removing Brush
3. J 9666 Valve Spring Tester. See «Special Tools»(ref-277938-S12463979202008012100000) .

1. Clean the valve stems and cylinder heads on a buffing wheel.
2. Clean the following components in cleaning solvent: Valve stem keys (1) Valve spring cap (2) Valve spring (3) Cylinder head
3. Dry the components with compressed air.
4. Use the J 8089 to clean the carbon from the cylinder head combustion chambers. Be careful not to scuff the combustion chambers.
5. Inspect the cylinder head for the following: Damage to the gasket surfaces Damage to the threaded bolt holes Burnt or eroded areas in the combustion chamber Cracks in the exhaust ports and combustion chambers External cracks in the water chamber Restrictions in the intake or exhaust passages Restrictions in the cooling system passages Rusted, damaged, or leaking core plugs
6. Measure the cylinder head for warpage with a straight edge and feeler gage. A cylinder head block deck with warpage in excess of 0.10 mm (0.004 in) within a 152.4 mm (6.0 in) area must be repaired or replaced. A cylinder head exhaust manifold deck with warpage in excess of 0.05 mm (0.002 in) within a 152.4 mm (6.0 in) area must be repaired or replaced. A cylinder head intake manifold deck with warpage in excess of 0.10 mm (0.004 in) within a 152.4 mm (6.0 in) area must be repaired or replaced.
7. Use the J 9666 in order to measure the valve spring. See «Special Tools»(ref-277938-S12463979202008012100000) . Replace the valve spring if the valve spring tension is less than 338 N (76 lb) at 43.2 mm (1.70 in).
8. Inspect the valve springs for squareness.
9. Valve stems (1) with excessive valve guide (2) clearance must be repaired or the cylinder head replaced.
10. Measure the valve stem-to-guide clearance. Excessive valve stem-to-guide clearance may cause an excessive oil consumption and may also cause a valve to break. Insufficient clearance will result in noisy and sticky functioning of the valve and will disturb the engine assembly smoothness. Clamp the J 8001 on the exhaust port side of the cylinder head. Position the dial 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 dial indicator stem. The dial indicator stem must contract the side of the valve stem just above the valve guide. Drop the valve head about 1.6 mm (0.063 in) off the valve seat. Use light pressure and move the valve stem from side to side in order to obtain a valve stem-to-guide clearance reading. Refer to «Engine Mechanical Specifications»(ref-277938-S01556385892008012100000) .

Oil Pump Cleaning and Inspection

1. Clean the oil pump components in cleaning solvent.
2. Dry the components with compressed air.
3. Inspect the oil pump for the following conditions: Scoring on the top of the gears (1) Damaged gears (2) for the following: Chipping Galling Wear Scoring, damage or casting imperfections to the body (3) Damaged or scored gear shaft (4) Damaged or scored gear shaft (5) Damaged bolt hole threads Worn oil pump driveshaft bore Damaged or sticking oil pump pressure relief valve Minor imperfections may be removed with a fine oil stone. Collapsed or broken oil pump pressure relief valve spring
4. If the oil pump is to be reused, install a NEW oil pump pressure relief valve spring.
5. During oil pump installation, install a NEW oil pump driveshaft retainer.

Valve Rocker Arm Cover Cleaning and Inspection

1. Clean the valve rocker arm cover in cleaning solvent.
2. Dry the valve rocker arm cover with compressed air.
3. Inspect the valve rocker arm cover for the following: Damage to the PCV orifice (1) Damage to the bolt holes (2) A damaged valve rocker arm cover may interfere with the valve rocker arms. Damage to the exterior of the valve rocker arm cover (3) Gouges or damage to the sealing surface (4) Damage to the oil fill tube grommet (5) Restrictions to the ventilation system passages

Oil Pan Cleaning and Inspection

1. Remove the oil pan baffle bolts and the oil pan baffle.
2. Clean the oil pan and oil pan baffle in cleaning solvent.
3. Dry the oil pan and oil pan baffle with compressed air.
4. Inspect the oil pan for the following: Gouges or damage to the oil pan sealing surfaces (1) Damage to the threaded holes (2) Damaged oil pan drain hole threads (3) Damage to the oil pan baffle Damage to the exterior of the oil pan A damaged oil pan may interfere with the proper position of the oil pump screen, or may not distribute oil properly in the oil pan sump area.
5. Install the oil pan baffle and the bolts. Tighten: Tighten the oil pan baffle bolts to 12 N.m (106 lb in).

Intake Manifold Cleaning and Inspection

1. Clean the upper intake manifold in cleaning solvent.
2. Dry the upper intake manifold with compressed air.
3. Clean the lower intake manifold in cleaning solvent.
4. Dry the lower intake manifold with compressed air.
5. Inspect the upper intake manifold for the following: Cracks or other damage to the exterior (1) Cracking or damage in the gasket grooves (2) and (3) Damage to the throttle body mounting surface (4) Loose or damaged bolt hole thread inserts (5)
6. Inspect the lower intake manifold for the following: Damage to the gasket sealing surfaces (1) and (2) Restricted cooling system passages (3) Cracks or damage Damage to the threaded bolt holes

Exhaust Manifold Cleaning and Inspection

1. Clean the exhaust manifolds in cleaning solvent.
2. Dry the components with compressed air.
3. Inspect the exhaust manifolds for the following: Damage to the gasket sealing surfaces (1) Damage to the threaded holes (2) Restrictions within exhaust passages Broken or damaged exhaust manifold heat shields (3), if applicable Broken or damaged exhaust manifold
4. Measure the alignment or surface flatness of the exhaust manifold flanges using a straight edge and a feeler gage. Refer to «Engine Mechanical Specifications»(ref-277938-S01556385892008012100000) . If the surface flatness is not within the specifications, the exhaust manifold is warped and must be replaced.

Water Pump Cleaning and Inspection

1. Remove the old gasket material from the water pump sealing surfaces.
2. Clean all the dirt and any debris from the water pump.
3. Inspect the water pump for the following: Leakage or damage to the housing cover or gasket (1) Excessive scratches or gouging to the gasket sealing surfaces (2) Leakage from the water pump vent hole (3) A stain around the vent hole is acceptable. If leakage occurred (dripping) with the engine operating and the cooling system pressurized, then replace the water pump. Damaged bolt hole threads (4) Excessive side-to-side movement of the water pump shaft (5) Leakage around the water inlet pipe (6) Leakage around the heater hose pipe (7) Restrictions within the internal coolant passages

Engine Mechanical Diagnostic Procedure Revisions

No changes for 2007.