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, or the 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 number(s) below refer to the step(s) in the diagnostic table.
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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.
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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.
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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.
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Inspection of the fasteners can eliminate the possibility that a 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. Also 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 diagnostic information, 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. 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 | -- | ||||
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 | -- | ||||
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 shaft. Did you find and correct the condition? | Go to Step 11 | Go to Step 10 | |||||
Inspect for bent or cracked accessory drive bracket(s). Did you find and correct the condition? | Go to Step 11 | -- | |||||
11 |
Does the vibration still exist? | -- | System OK | ||||
