Results Of Incorrect Operation
- A plugged valve (3 ) or hose (2 & 4 ) may cause the following conditions: Rough idle Stalling or a low idle speed Oil leaks Oil in the air cleaner Sludge in the engine
- A leaking crankcase ventilation valve (3 ) or hose (2 & 4 ) may cause the following conditions: Rough idle Stalling High idle speed
Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2: This test is to verify that the symptom is present during diagnosing. Other vehicle components may cause a similar symptom such as the exhaust system or the drivetrain.
- 3: This test is to verify that the drive belts or accessory drive components may be causing the vibration. When removing the drive belt, the water pump may not be operating and the engine may overheat. Also DTCs may set when the engine is operating with the drive belt removed.
- 4: The drive belts may cause a vibration. While the drive belts are removed, this is the best time to inspect the condition of the belt.
- 6: Inspecting of the fasteners can eliminate the possibility that a wrong bolt, nut, spacer or washer was installed.
- 8: This step should only be performed if the fan is driven by the drive belt. Inspect the engine cooling fan for bent, twisted, loose or cracked blades. Inspect the fan clutch for smoothness, ease of turning. Inspect for a bent fan shaft or bent mounting flange.
- 9: This step should only be performed if the water pump is driven by the drive belt. Inspect the water pump shaft for being bent. Also inspect the water pump bearings for smoothness and excessive play. Compare the water pump with a known good water pump.
- 10: Accessory drive component brackets that are bent, cracked or loose may put extra strain on that accessory component causing it to vibrate.
| Step | Action | Yes | No |
|---|---|---|---|
| NOTE: Refer to BELT DRESSING NOTICE in Cautions and Notices. DEFINITION: The following items are indications of drive belt vibration: The vibration is engine-speed related. The vibration may be sensitive to accessory load. | |||
| 1 | Did you review the Symptoms - Engine Mechanical operation and perform the necessary inspections? | Go to Step 2 | Go to Vibration Analysis - Engine in Vibration Diagnosis and Correction |
| 2 | Verify that the vibration is engine related. Does the engine make the vibration? | Go to Step 3 | Go to Diagnostic Aids |
| 3 | Remove the drive belt. Refer to Drive Belt Replacement . Operate the engine for no longer than 30-40 seconds. Does the engine still make the vibration? | Go to Diagnostic Starting Point - Vibration Diagnosis and Correction in Vibration Diagnosis and Correction | Go to Step 4 |
| 4 | Inspect the drive belt for wear, damage, debris build-up and missing drive belt ribs. Did you find any of these conditions? | Go to Step 5 | Go to Step 6 |
| 5 | Install a new drive belt. Refer to Drive Belt Replacement . Did you complete the replacement? | Go to Step 11 | |
| 6 | Inspect for improper, loose or missing fasteners. Did you find any of these conditions? | Go to Step 7 | Go to Step 8 |
| 7 | Tighten any loose fasteners. Replace improper or missing fasteners. Refer to Fasteners in General Information. Did you complete the repair? | Go to Step 11 | |
| 8 | Inspect for damaged fan blades or bent fan clutch shaft, if the fan is belt driven. Did you find and correct the condition? | Go to Step 11 | Go to Step 9 |
| 9 | Inspect for a bent water pump shaft, if the water pump is belt driven. Did you find and correct the condition? | Go to Step 11 | Go to Step 10 |
| 10 | Inspect for bent or cracked brackets. Did you find and correct the condition? | Go to Step 11 | Go to Diagnostic Aids |
| 11 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
| NOTE |
|---|
| Refer to BELT DRESSING NOTICE in Cautions and Notices. |
Drive Belt Vibration Diagnosis
The numbers below refer to the step numbers on the diagnostic table.
- 2: This inspection is to verify the condition of the drive belt. Damage to the belt may have occurred when it came off of the pulleys. The drive belt may have been damaged, which caused the drive belt to fall off. Inspect the belt for cuts, tears, sections of ribs missing or damaged belt plys.
- 4: Misalignment of the pulleys may be caused from improper mounting of the accessory drive component, incorrect installation of the accessory drive component pulley or the pulley bent inward or outward from a previous repair. Test for a misaligned pulley using a straight edge in the pulley grooves across 2 or 3 pulleys. If a misaligned pulley is found, refer to that accessory drive component for the proper installation procedure for that pulley.
- 5: Inspecting the pulleys for being bent should include inspecting for a dent or other damage to the pulleys that would prevent the drive belt from not seating properly in all of the pulley grooves or on the smooth surface of a pulley when the back side of the belt is used to drive the pulley.
- 6: Accessory drive component brackets that are bent or cracked will let the drive belt fall off.
- 7: Inspecting of the fasteners can eliminate the possibility that a wrong bolt, nut, spacer or washer was installed. Missing, loose or the wrong fasteners may cause pulley misalignment from the bracket moving under load. Over tightening of the fasteners may cause misalignment of the accessory component bracket.
| Step | Action | Yes | No |
|---|---|---|---|
| NOTE: Refer to BELT DRESSING NOTICE in Cautions and Notices. DEFINITION: The drive belt falls off the pulleys or may not ride correctly on the pulleys. | |||
| 1 | Did you review the Symptoms - Engine Mechanical operation and perform the necessary inspections? | Go to Step 2 | Go to Drive Belt System Description |
| 2 | Inspect for a damaged drive belt. Did you find the condition? | Go to Step 3 | Go to Step 4 |
| 3 | Install a new drive belt. Refer to Drive Belt Replacement . Does the drive belt continue to fall off? | Go to Step 4 | System OK |
| 4 | Inspect for misalignment of the pulleys. Did you find and repair the condition? | Go to Step 12 | Go to Step 5 |
| 5 | Inspect for a bent or dented pulley. Did you find and repair the condition? | Go to Step 12 | Go to Step 6 |
| 6 | Inspect for a bent or a cracked bracket. Did you find and repair the condition? | Go to Step 12 | Go to Step 7 |
| 7 | Inspect for improper, loose or missing fasteners. Did you find loose or missing fasteners? | Go to Step 8 | Go to Step 9 |
| 8 | Tighten any loose fasteners. Replace improper or missing fasteners. Refer to Fasteners in General Information. Does the drive belt continue to fall off? | Go to Step 9 | System OK |
| 9 | Test the drive belt tensioner for operating correctly. Refer to Drive Belt Tensioner Diagnosis . Does the drive belt tensioner operate correctly? | Go to Step 11 | Go to Step 10 |
| 10 | Replace the drive belt tensioner. Refer to Drive Belt Tensioner Replacement . Does the drive belt continue to fall off? | Go to Step 11 | System OK |
| 11 | Inspect for failed drive belt idler and drive belt tensioner pulley bearings. Did you find and repair the condition? | Go to Step 12 | Go to Diagnostic Aids |
| 12 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
| NOTE |
|---|
| Refer to BELT DRESSING NOTICE in Cautions and Notices. |
Drive Belt Falls Off Diagnosis
The numbers below refer to the step numbers on the diagnostic table.
- 2: The inspection is to verify the drive belt is correctly installed on all of the drive belt pulleys. Wear on the drive belt may be caused by mispositioning the drive belt by one groove on a pulley.
- 3: The installation of a drive belt that is too wide or too narrow will cause wear on the drive belt. The drive belt ribs should match all of the grooves on all of the pulleys.
- 4: This inspection is to verify the drive belt is not contacting any parts of the engine or body while the engine is operating. There should be sufficient clearance when the drive belt accessory drive components load varies. The drive belt should not come in contact with an engine or a body component when snapping the throttle.
| Step | Action | Yes | No |
|---|---|---|---|
| NOTE: Refer to Belt Dressing Notice in Cautions and Notices. DEFINITION: Wear at the outside ribs of the drive belt due to an incorrectly installed drive belt. | |||
| 1 | Did you review the Symptoms - Engine Mechanical operation and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Mechanical |
| 2 | Inspect the drive belt for the proper installation. Refer to Drive Belt Replacement . Did you find this condition? | Go to Step 5 | Go to Step 3 |
| 3 | Inspect for the proper drive belt. Did you find this condition? | Go to Step 5 | Go to Step 4 |
| 4 | Inspect for the drive belt rubbing against a bracket, hose or wiring harness. Did you find and repair the condition? | Go to Step 6 | Go to Diagnostic Aids |
| 5 | Replace the drive belt. Refer to Drive Belt Replacement . Did you complete the replacement? | Go to Step 6 | |
| 6 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | |
| NOTE |
|---|
| Refer to Belt Dressing Notice in Cautions and Notices. |
Drive Belt Excessive Wear Diagnosis
Drive Belt System Description
The drive belt system consists of the following components
- The drive belt
- The drive belt tensioner
- The crankshaft balancer pulley
- The accessory drive components The generator The A/C compressor The water pump
The drive belt system uses one belt. The drive belt is thin so that it can bend backwards and has several ribs to match the grooves in the pulleys. The drive belt is made of different types of rubbers (chloroprene or EPDM) and have different layers or plys containing either fiber cloth or cords for reinforcement.
Both sides of the drive belt may be used to drive the different accessory drive components. When the back side of the drive belt is used to drive a pulley, the pulley is smooth.
The drive belt is pulled by the crankshaft balancer pulley across the accessory drive component pulleys. The spring loaded drive belt tensioner keeps constant tension on the drive belt to prevent the drive belt from slipping. The drive belt tensioner arm will move when loads are applied to the drive belt by the accessory drive components and the crankshaft.
Engine Component Description
The cylinder block is made of cast alloy iron. The cylinder block has 6 cylinders that are arranged in a V shape. There are 3 cylinders in each bank. The cylinder banks are set at a 60 degree angle from each other.
Starting from the front of the engine - accessory belt end, the right bank cylinders are 2, 4, 6. The left bank cylinders are 1, 3, 5.
Four main bearings support the crankshaft. The crankshaft is retained by the bearing caps. The bearing caps are machined with the block for proper alignment and clearances. The main bearing caps are drilled and tapped for the structural oil pan side bolts.
The aluminum cylinder heads have individual intake and exhaust ports for each cylinder. The valve guides are pressed in. The roller rocker arms are located on a pedestal in a slot in the cylinder head. The roller rocker arms are retained on individual threaded bolts.
The crankshaft is forged steel - some applications use cast iron, with deep rolled fillets on all 6 crankpins and all 4 main journals. Four steel-backed aluminum bearings are used. The #3 bearing is the end-thrust bearing.
The camshaft is made from a new metal composite design. The camshaft profile is a hydraulic roller design. The camshaft is supported by 4 journals. The camshaft includes an oil pump drive gear.
The pistons are cast aluminum using 2 compression rings and 1 oil control ring. The pistons also have 2 polymer coated patches on the skirt for noise reduction. The piston pin is offset 0.8 mm (0.031 in) towards the major thrust side. This placement allows for a gradual change in thrust pressure against the cylinder wall as the piston travels its path. The pins are made of chromium steel and have a floating fit in the pistons. The pins are retained in the connecting rods by a press fit.
The connecting rods are made of forged steel. Full pressure lubrication is directed to the connecting rods by drilled oil passages from the adjacent main bearing journal.
A roller rocker type valve train is used. Motion is transmitted from the camshaft through the hydraulic roller lifter and from the pushrod to the roller rocker arm. The rocker arm pivots on the needle roller bearings. The rocker arm transmits the camshaft motion to the valve. The rocker arm pedestal is located in a slot in the cylinder head. The rocker arm is retained in the cylinder head by a bolt. The pushrod is located by the rocker arm.
The intake manifold is a 2-piece cast aluminum unit. The intake manifold centrally supports a fuel rail with 6 fuel injectors.
The exhaust manifolds are cast nodular iron.
Scheme 1
Full pressure lubrication, through a full flow oil filter, is furnished by a gear type oil pump. The oil is drawn up through the pickup screen and the tube. The oil passes through the pump to the oil filter.
The oil filter is a full flow paper element unit. An oil filter bypass is used in order to ensure oil supply during the following conditions
- On a cold start
- If the filter is plugged
- If the filter develops excessive pressure drop
The bypass is designed to open at 69-83 kPa (10-12 psi).
A priority oil delivery system supplies oil first to the crankshaft journals. The oil from the crankshaft main bearings is supplied to the connecting rod bearings by intersecting the passages drilled in the crankshaft. The passages supply the oil to the crankshaft main bearings and the camshaft bearings through the intersecting vertical drilled holes. The oil passages from the camshaft journals supply oil to the hydraulic lifters.
The piston oil nozzle lubricates the pistons and cylinder walls in cylinders 5 and 6. A nonserviceable check valve integrated into the nozzle prevents oil bleed down from the nozzle when the engine is not running.
The hydraulic lifters pump oil up through the pushrods to the rocker arms. The cast dams in the crankcase casting direct the oil that drains back from the rocker arms in order to supply the camshaft lobes. The camshaft chain drive is lubricated by indirect oil splash.
