Diagnostic Aids
The accessory drive components may have an affect on engine vibration. An overcharged air conditioning (A/C) system, a power steering system restriction incorrect fluid, or an extra load placed on the generator are suggested items to inspect. 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 steps in the diagnostic table.
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This step verifies that the vibration is present during diagnosis. Other vehicle components may cause a similar symptom, such as the exhaust system or the drive train.
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This step verifies 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 verifies if the vibration is related to the drive belt. With the drive belt removed, the water pump does not operate and the engine may overheat. Diagnostic trouble codes (DTCs) may set when the engine is operated with the drive belt removed.
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The drive belt may cause a vibration. While the drive belt is removed, is the best time to inspect the condition of the drive belt.
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Inspection of the fasteners can eliminate the possibility that an incorrect 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 smooth operation. Inspect for a bent fan shaft or bent mounting flange.
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Inspect the water pump drive shaft for being bent. Inspect the water pump bearings for smooth operation 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 an extra strain on that accessory drive component causing it to vibrate.
Step | Action | Yes | No | ||||
|---|---|---|---|---|---|---|---|
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Notice: Refer to Belt Dressing Notice in the Preface section. DEFINITION: The following items are indications of drive belt vibration:
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1 | Did you review the Symptoms - Engine Mechanical 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 Diagnostic Starting Point - 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 Drive Belt Replacement - Accessory or Drive Belt Replacement - Air Conditioning. Did you complete the replacement? | Go to Step 11 | -- | ||||
Inspect for incorrect, loose and/or missing fasteners. Did you find any of these conditions? | 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 . Did you replace and/or tighten any fasteners? | Go to Step 11 | -- | ||||
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 | |||||
Inspect for a bent water pump drive shaft. Did you find and correct the condition? | Go to Step 11 | Go to Step 10 | |||||
Inspect for a bent or cracked accessory drive bracket. Did you find and correct the condition? | Go to Step 11 | -- | |||||
11 |
Does the vibration still exist? | -- | System OK | ||||
