Diagnostic Aids
The accessory drive components may have an affect on engine vibration. An overcharged A/C system, a power steering system restriction, or incorrect fluid, or an extra load placed on the generator are some systems that should be inspected. 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 number(s) on the diagnostic table.
-
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.
-
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 operate and the engine may overheat. Also DTCs may set when the engine is operated with the drive belt removed.
-
The drive belt may cause a vibration. With the drive belt removed inspect the condition of the drive belt.
-
Inspection of the fasteners can eliminate the possibility that a wrong bolt, nut, spacer, or washer was installed.
-
This step should only be performed if the cooling 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.
-
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 smooth operation and excessive play. Compare the water pump with a known good water pump.
-
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 | ||||
|---|---|---|---|---|---|---|---|
|
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:
| |||||||
1 | Did you review the Symptoms - Drive Belt diagnostic information and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Drive Belt | ||||
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 Engine Related Vibration in Vibration and Diagnosis | 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 . Did you complete the replacement? | Go to Step 11 | -- | ||||
Inspect for improper, missing or loose fasteners. Did you find any of these conditions? | Go to Step 7 | Go to Step 8 | |||||
7 | Tighten any loose fasteners. Refer to Fastener Tightening Specifications . Replace improper or missing fasteners. 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 Engine Coolant Fan Motor 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 | Run the engine in order to verify the repair. Does the drive belt still vibrate? | Go to Step 3 | System OK | ||||
