Diagnostic Aids
The accessory drive components can have an affect on engine vibration. Some of the causes of component vibration can be that the A/C system is over charged, the power steering system is restricted or has incorrect fluid, or there is an extra load on the generator. To help identify an intermittent or an improper condition, vary the loads on the accessory drive components.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This test is to verify that the symptom is present during diagnosing. Other vehicle components, such as the exhaust system or the drivetrain, may cause a similar symptom.
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This test is to verify that the drive belt or accessory drive components may be causing the vibration. With the drive belt removed 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.
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The drive belt may cause a vibration. The best time to inspect the condition of the drive belt is while it is removed from the vehicle.
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Inspection of the fasteners can determine if a wrong bolt, nut, spacer, or washer was installed.
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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 and ease of turning. Inspect for a bent fan shaft or bent mounting flange.
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This step should only be performed if the water pump is driven by the drive belt. Inspect the water pump for a bent shaft. Also inspect the water pump bearings for smoothness and excessive play. Compare the water pump with a known good water pump.
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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 | ||||
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Notice: Do not use belt dressing on the drive belt. Belt dressing causes the breakdown of the composition of the drive belt. Failure to follow this recommendation will damage the drive belt. DEFINITION: The following items are indications of drive belt vibration:
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1 | Did you review the Drive Belt Symptom operation and perform the necessary inspections? | Go to Step 2 | |||||
Verify that the vibration is engine related. Does the engine make the vibration? | Go to Step 3 | Go to Diagnostic Aids | |||||
Does the engine still make the vibration? | Go to Symptoms - Vibration Diagnosis and Correction in Vibration Diagnosis and Correction | Go to Step 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 Generator and Air Conditioning Compressor and Power Steering Pump Belt Replacement and Drive Belt Tensioner Replacement - Cooling Fan . Did you complete the replacement? | Go to Step 11 | -- | ||||
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 Fastener Tightening Specifications . Did you complete the repair? | Go to Step 11 | -- | ||||
Inspect for damaged fan blades or bent fan clutch shaft, if the fan is belt driven. Refer to Fan Clutch Replacement in Engine Cooling. Did you find and correct the condition? | Go to Step 11 | Go to Step 9 | |||||
Inspect for a bent water pump shaft, if the water pump is belt driven. Refer to Water Pump Replacement in Engine Cooling. Did you find and correct the condition? | Go to Step 11 | Go to Step 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 | ||||
