Results Of Incorrect Operation
- A plugged valve or hose may cause the following conditions: Rough idle Stalling or slow idle speed Oil leaks Oil in air cleaner Sludge in engine
- A leaking crankcase ventilation valve or hose may cause the following conditions: Rough idle Stalling High idle speed
Test Description
The number(s) below refer to the step(s) in the diagnostic table.
- 2: The chirping noise may not be engine related. This step is to verify that the engine is making the noise. If the engine is not making the noise do not proceed further with his table.
- 3: The noise may be an internal engine noise. Remove the drive belt and operate the engine for a few seconds, this will verify if the chirping noise is related to the drive belt or not. With the drive belt removed the water pump will not operate and the engine may overheat. Also diagnostic trouble codes (DTCs) may set when the engine is operated with the drive belt removed.
- 4: Inspect the drive belt for signs of pilling. Pilling is the small balls, pills, or strings in the drive belt grooves caused by the accumulation of rubber dust.
- 6: Misalignment of the accessory drive pulley(s) may be caused from improper mounting or incorrect installation of an accessory drive component, or the pulley may be bent inward or outward from a previous repair. Test for a misaligned pulley using a straight edge in the pulley grooves across two or three pulleys. If a misaligned pulley is found, refer to that accessory drive component for the proper removal and installation procedure for that pulley.
- 10: Inspection of the fasteners can eliminate the possibility that a incorrect bolt, nut, spacer, or washer was installed.
- 12: Inspect the accessory drive pulley(s) should include inspecting for bends, dents or other damage to the pulley(s) that would prevent the drive belt from seating properly in the pulley grooves, or on the smooth surface of the pulley when the back side of the drive belt is used to drive the pulley.
- 14: Replacing the drive belt when it is not damaged or there is not excessive pilling will only be a temporary repair.
| Step | Action | Yes | No |
|---|---|---|---|
| NOTE: Refer to Belt Dressing Notice in Cautions and Notices. DEFINITION: The following items are indications of chirping: A high pitched noise that is heard once per revolution of the drive belt or a accessory drive pulley. Chirping may occur on cold damp start-up conditions and will subside once the vehicle reaches normal operating temperature. | |||
| 1 | Did you review the Symptoms - Engine Mechanical diagnostic information, and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Mechanical |
| 2 | Verify that there is a chirping noise. Does the engine make the chirping noise? | 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 to 40 seconds. Does the chirping noise still exist? | Go to Engine Noise on Start-Up, but Only Lasting a Few Seconds | Go to Step 4 |
| 4 | Inspect for severe drive belt pilling exceeding 1/3 of the drive belt groove depth. Does the drive belt grooves have pilling? | Go to Step 5 | Go to Step 6 |
| 5 | Clean the accessory drive belt pulley(s) with a suitable wire brush. Were the accessory drive belt pulley(s) cleaned? | Go to Step 15 | |
| 6 | Inspect for a misaligned accessory drive pulley(s). Is there a misaligned pulley(s)? | Go to Step 7 | Go to Step 8 |
| 7 | Replace and/or repair the misaligned accessory drive pulley(s). Were the misaligned accessory drive pulley(s) replaced and/or repaired? | Go to Step 15 | |
| 8 | Inspect for a bent or cracked accessory drive bracket(s). Is there a bent and/or cracked accessory drive bracket(s)? | Go to Step 9 | Go to Step 10 |
| 9 | Replace the bent and/or cracked accessory drive bracket(s). Was the bent and/or cracked accessory drive bracket(s) replaced? | Go to Step 15 | |
| 10 | Inspect for incorrect, loose and/or missing fasteners. Were there any incorrect, loose, and/or missing fasteners found? | Go to Step 11 | Go to Step 12 |
| 11 | Replace any incorrect and/or missing fasteners. Tighten any loose fasteners. Refer to Fastener Tightening Specifications . Were the fasteners replaced and/or tightened? | Go to Step 15 | |
| 12 | Inspect for a bent accessory drive pulley(s). Was a bent accessory drive pulley(s) found? | Go to Step 13 | Go to Step 14 |
| 13 | Replace the bent accessory drive pulley(s). Was the bent accessory drive pulley(s) replaced? | Go to Step 15 | |
| 14 | Replace the drive belt. Refer to Drive Belt Replacement . Was the drive belt replaced? | Go to Step 15 | |
| 15 | Clear any codes. Run the engine in order to verify the repair. Does the chirping noise still exist? | System OK | |
| NOTE |
|---|
| Refer to Belt Dressing Notice in Cautions and Notices. |
Drive Belt Chirping Diagnosis
The number(s) below refer to the step(s) in the diagnostic table.
- 2: The squeal may not be engine related. This step is to verify that the engine is making the noise. If the engine is not making the noise do not proceed further with this table
- 3: The squeal may be an internal engine noise. Remove the drive belt and operate the engine for a few seconds, this will verify if the squealing noise is related to the drive belt or an accessory drive component. With the drive belt removed the water pump will not operate and the engine may overheat. Also diagnostic trouble codes (DTCs) may set when the engine is operated with the drive belt removed.
- 4: This test is to verify that an accessory drive component(s) does not have a seized bearing. With the belt removed test the bearings in the accessory drive component(s) for smooth operation. Also test the accessory drive components with the engine operating by varying the load on the accessory drive component(s) to verify that the component(s) is operating properly.
- 5: This test is to verify that the drive belt tensioner is operating properly. If the drive belt tensioner is not operating properly, proper belt tension may not be achieved to keep the drive belt from slipping which could cause a squealing noise.
- 6: This test is to verify that the drive belt is not too long, which would prevent the drive belt tensioner from operating properly. Also if the incorrect length drive belt was installed, it may not be routed correctly and may be turning an accessory drive component in the incorrect direction.
- 7: Misalignment of the accessory drive pulley(s) may be caused from improper mounting or incorrect installation of a accessory drive component, or the pulley may be bent inward or outward from a previous repair. Test for a misaligned pulley using a straight edge in the pulley grooves across two or three pulleys. If a misaligned pulley is found, refer to that accessory drive component for the proper removal and installation procedure for that pulley.
- 8: Inspect the accessory drive pulley(s) to verify that they are the correct diameter or width. Using a known good vehicle, compare the accessory drive pulleys.
| Step | Action | Yes | No |
|---|---|---|---|
| NOTE: Refer to Belt Dressing Notice in Cautions and Notices. DEFINITION: The following items are indications of drive belt squeal: A loud screeching noise that is caused by a slipping drive belt (this is unusual for a drive belt with multiple ribs) The squeal occurs when a heavy load is applied to the drive belt, such as an A/C compressor engagement, snapping the throttle, slipping on a seized pulley, or a faulty accessory drive component. | |||
| 1 | Did you review the Symptoms - Engine Mechanical diagnostic information, and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Mechanical |
| 2 | Verify that there is a squealing noise. Does the engine make the squeal noise? | 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 to 40 seconds. Does the squealing noise still exist? | Go to Engine Noise on Start-Up, but Only Lasting a Few Seconds | Go to Step 4 |
| 4 | Inspect for a seized accessory drive component bearing or a faulty accessory drive component. Did you find and correct the condition? | Go to Step 9 | Go to Step 5 |
| 5 | Inspect the drive belt tensioner for proper operation. Refer to Drive Belt Tensioner Diagnosis . Did you find and correct the condition? | Go to Step 9 | Go to Step 6 |
| 6 | Check for the correct length drive belt. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
| 7 | Inspect for a misaligned pulley. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
| 8 | Inspect for an incorrect size pulley. Did you find and correct the condition? | Go to Step 9 | |
| 9 | Install the drive belt. Refer to Drive Belt Replacement . Clear any codes. Run the engine in order to verify the repair. Does the squealing noise still exist? | System OK | |
| NOTE |
|---|
| Refer to Belt Dressing Notice in Cautions and Notices. |
Drive Belt Squeal Diagnosis
The number(s) below refer to the step(s) in the diagnostic table.
- 3: This test is to verify that the whine is being caused by the accessory drive component(s). Remove the drive belt and operate the engine for a few seconds, this will verify if the whining noise is related to the accessory drive component. With the drive belt removed the water pump will not operate and the engine may overheat. Also diagnostic trouble codes (DTCs) may set when the engine is operated with the drive belt removed.
- 4: This inspection should include checking the drive belt tensioner and the drive belt idler pulley bearings. The drive belt may have to be installed and the accessory drive component(s) operated separately by varying their loads. Refer to the suspected accessory drive component for the proper removal and replacement procedure.
| Step | Action | Yes | No |
|---|---|---|---|
| NOTE: Refer to Belt Dressing Notice in Cautions and Notices. DEFINITION: A high pitched continuous noise that may be caused by an accessory drive component failed bearing. | |||
| 1 | Did you review the Symptoms - Engine Mechanical diagnostic information, and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Mechanical |
| 2 | Verify that there is a whining noise. Does the engine make the whine noise? | Go to Step 3 | Go to Diagnostic Aids |
| 3 | Remove the drive belt. Drive Belt Replacement . Operate the engine for no longer than 30 to 40 seconds. Does the whining noise still exist? | Go to Engine Noise on Start-Up, but Only Lasting a Few Seconds | Go to Step 4 |
| 4 | Inspect for a failed accessory drive component bearing. Install the drive belt. Drive Belt Replacement . Did you find and correct the condition? | Go to Step 5 | |
| 5 | Clear any codes. Run the engine in order to verify the repair. Does the whining still exist? | System OK | |
| NOTE |
|---|
| Refer to Belt Dressing Notice in Cautions and Notices. |
Drive Belt Whine Diagnosis
The number(s) below refer to the step(s) in the diagnostic table.
- 2: This test is to verify that the symptom is present during diagnosing. Other vehicle components may cause a similar symptom.
- 3: This test is to verify that the drive belt is causing the rumbling. Rumbling may be confused with an internal engine noise due to the similarity in the description. Operate the engine for a few seconds, this will verify if the rumbling noise is related to the drive belt or not. With the drive belt removed the water pump will not operate and the engine may overheat. Also diagnostic trouble codes (DTCs) may set when the engine is operated with the drive belt removed.
- 4: Inspect the drive belt to ensure that the drive belt is not the cause of the noise. Small cracks across the ribs of the drive belt will not cause the noise. Belt separation is identified by the plys of the belt separating, this may be seen at the edge of the belt or felt as a lump in the belt.
- 5: Small amounts of pilling is a normal condition and acceptable. When the pilling is severe the drive belt does not have a smooth surface for proper operation.
| Step | Action | Yes | No |
|---|---|---|---|
| NOTE: Refer to Belt Dressing Notice in Cautions and Notices. DEFINITION: A low pitch tapping, knocking, or thumping noise heard at or just above idle. Heard once per revolution of the drive belt or a pulley(s). Rumbling may be caused from: Pilling, the accumulation of rubber dust that forms small balls (pills) or strings in the drive belt pulley groove The separation of the drive belt A damaged drive belt | |||
| 1 | Did you review the Symptoms - Engine Mechanical diagnostic information, and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Mechanical |
| 2 | Verify that there is a rumbling noise. Does the engine make the rumbling noise? | Go to Step 3 | Go to Diagnostic Aids |
| 3 | Remove the drive belt(s). Refer to Drive Belt Replacement . Operate the engine for no longer than 30 to 40 seconds. Does the rumbling noise still exist? | Go to Engine Noise on Start-Up, but Only Lasting a Few Seconds | Go to Step 4 |
| 4 | Inspect the drive belt for damage, separation, or sections of missing ribs. Were any of these conditions found? | Go to Step 7 | Go to Step 5 |
| 5 | Inspect for severe pilling of more than 1/3 of the drive belt groove depth. Do the drive belt grooves have pilling? | Go to Step 6 | Go to Step 7 |
| 6 | Clean the drive belt pulleys using a suitable wire brush. Install the drive belt. Refer to Drive Belt Replacement . Did you complete the repair? | Go to Step 8 | |
| 7 | Install a new drive belt. Refer to Drive Belt Replacement . Did you complete the replacement? | Go to Step 8 | |
| 8 | Clear any codes. Run the engine in order to verify the repair. Does the rumbling noise still exist? | System OK | |
| NOTE |
|---|
| Refer to Belt Dressing Notice in Cautions and Notices. |
Drive Belt Rumbling Diagnosis
The number(s) below refer to the step(s) in the diagnostic table.
- 2: This test is to verify that the vibration 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 belt or accessory drive components may be causing the vibration. Remove the drive belt and operate the engine for a few seconds, this will verify if the vibration is related to the drive belt or not. With the drive belt removed the water pump will not operate and the engine may overheat. Also diagnostic trouble codes (DTCs) may set when the engine is operated with the drive belt removed.
- 4: The drive belt may cause a vibration. While the drive belt is removed this is the best time to inspect the condition of the drive belt.
- 6: Inspection of the fasteners can eliminate the possibility that a incorrect 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 smooth operation. Inspect for a bent fan shaft or bent mounting flange.
- 9: Inspect the water pump drive shaft for being bent. Also inspect the water pump bearings for smooth operation 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 an extra strain on that accessory drive 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 diagnostic information, and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Mechanical |
| 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 to 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. Were any of these conditions found? | 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 incorrect, loose and/or missing fasteners. Were any of these conditions found? | Go to Step 7 | Go to Step 8 |
| 7 | Replace any incorrect and/or missing fastener. Tighten any loose fasteners. Refer to Fastener Tightening Specifications . Were the fasteners replaced and/or tightened? | Go to Step 11 | |
| 8 | Inspect for damaged fan blades or a bent fan clutch shaft. Did you find and correct the condition? | Go to Step 11 | Go to Step 9 |
| 9 | Inspect for a bent water pump shaft. Did you find and correct the condition? | Go to Step 11 | Go to Step 10 |
| 10 | Inspect for bent or cracked accessory drive bracket(s). Did you find and correct the condition? | Go to Step 11 | |
| 11 | Clear any codes. Run the engine in order to verify the repair. Does the vibration still exist? | System OK | |
| NOTE |
|---|
| Refer to Belt Dressing Notice in Cautions and Notices. |
Drive Belt Vibration Diagnosis
The number(s) below refer to the step(s) on the diagnostic table.
- 2: This inspection is to verify the condition of the drive belt. Damage may have occurred to the drive belt when the drive belt fell off. Inspect the belt for cuts, tears, sections of ribs missing, or damaged belt plys.
- 4: Misalignment of the accessory drive pulley(s) may be caused from improper mounting or incorrect installation of a accessory drive component, or the pulley may be bent inward or outward from a previous repair. Test for a misaligned pulley using a straight edge in the pulley grooves across two or three pulleys. If a misaligned pulley is found, refer to that accessory drive component for the proper removal and installation procedure of that pulley.
- 5: Inspection of the accessory drive pulley(s) should include inspecting for bends, dents or other damage to the pulleys that would prevent the drive belt from seating properly in the pulley grooves or on the smooth surface of a pulley when the back side of the drive belt is used to drive the pulley.
- 6: Accessory drive component brackets that are bent or cracked will also cause the drive belt to fall off.
- 7: Inspection of the fasteners can eliminate the possibility that a incorrect bolt, nut, spacer, or washer was installed. Missing, loose, or incorrect fasteners may cause pulley misalignment from the accessory drive bracket(s) moving under load. Over tightening the fasteners may cause misalignment of the accessory component bracket(s).
| 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 diagnostic information, and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Mechanical |
| 2 | Inspect for a damaged drive belt. Was a damaged drive belt found? | 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 misaligned accessory drive pulley. Did you find and correct the condition? | Go to Step 12 | Go to Step 5 |
| 5 | Inspect for a bent or dented accessory drive pulley. Did you find and correct the condition? | Go to Step 12 | Go to Step 6 |
| 6 | Inspect for a bent or a cracked accessory drive bracket(s). Did you find and correct the condition? | Go to Step 12 | Go to Step 7 |
| 7 | Inspect for incorrect, loose and/or missing fasteners. Were there any incorrect, loose and/or missing fasteners? | Go to Step 8 | Go to Step 9 |
| 8 | Replace any incorrect and/or missing fasteners. Tighten any loose fasteners. Refer to Fastener Tightening Specifications . Does the drive belt continue to fall off? | Go to Step 9 | System OK |
| 9 | Test the drive belt tensioner for correct operation. 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 a failed drive belt idler and/or tensioner pulley bearings. Did you find and repair the condition? | Go to Step 12 | |
| 12 | Run the engine in order to verify the repair. Does the drive belt still fall off? | System OK | |
| NOTE |
|---|
| Refer to Belt Dressing Notice in Cautions and Notices. |
Drive Belt Falls Off Diagnosis
The number(s) below refer to the step(s) in the diagnostic table.
- 2: This inspection is to verify that the drive belt is correctly installed on all of the accessory drive pulleys. Wear on the drive belt may be caused by mis-positioning the drive belt by one groove on a pulley(s).
- 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 the pulleys.
- 4: This inspection is to verify the drive belt is not contacting any part of the engine or body while the engine is operating. There should be sufficient clearance when the 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 diagnostic information, and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Mechanical |
| 2 | Inspect the drive belt(s) for proper installation. Is the drive belt installed properly? | Go to Step 5 | Go to Step 3 |
| 3 | Inspect for the correct drive belt. Is the correct drive belt installed? | Go to Step 5 | Go to Step 4 |
| 4 | Inspect the drive belt for signs of rubbing against a bracket, hose, or wiring harness. Was the drive belt rubbing against anything? | Go to Step 5 | Go to Diagnostic Aids |
| 5 | Replace the drive belt. Refer to Drive Belt Replacement . Did you complete the replacement? | Go to Step 6 | |
| 6 | Run the engine in order to verify the repair. Is there still excessive drive belt wear? | System OK | |
| NOTE |
|---|
| Refer to Belt Dressing Notice in Cautions and Notices. |
Drive Belt Excessive Wear Diagnosis
Crankcase Ventilation System Description
A crankcase ventilation system is used in order to provide a more complete scavenging of crankcase vapors. The air cleaner supplies fresh air through a filter to the crankcase. The crankcase mixes the fresh air with blow-by gases. This mixture then passes through a crankcase ventilation valve into the intake manifold.
The primary control is through the crankcase ventilation valve (1), which meters the flow at a rate depending on the manifold vacuum.
In order to maintain an idle quality, the crankcase ventilation valve restricts the flow when the intake manifold vacuum is high. If abnormal operating conditions arise, the system is designed in order to allow the excessive amounts of blow-by gases to back flow through the crankcase vent tube into the air cleaner in order to be consumed by normal combustion.
Scheme 1
Drive Belt System Description
The drive belt system consists of the following components
- The drive belt
- The drive belt tensioner
- The drive belt idler pulley
- The crankshaft balancer pulley
- The accessory drive component mounting brackets
- The accessory drive components The power steering pump, if belt driven The generator The A/C compressor, if equipped The engine cooling fan, if belt driven The water pump, if belt driven The vacuum pump, if equipped The air compressor, if equipped
The drive belt system may use 1 belt or 2 belts. The drive belt is thin so that it can bend backwards and has several ribs to match the grooves in the pulleys. There also may be a V-belt style belt used to drive certain accessory drive components. The drive belts are 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.
The drive belt system may have an idler pulley, which is used to add wrap to the adjacent pulleys. Some systems use an idler pulley in place of an accessory drive component when the vehicle is not equipped with the accessory.