For 1990-2009 cars

## Drive Belt Rumbling and Vibration Diagnosis Vibration

### Diagnostic Aids

The accessory drive components can have an affect on engine vibration. Such as, but not limited to, the A/C system over charged, the power steering system restricted or the incorrect fluid, or an extra load on the alternator. To help identify an intermittent or an incorrect condition, vary the loads on the accessory drive components.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 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.

2. This test is to verify that the drive belt or accessory drive components may be causing the vibration. When removing the drive belt the water pump will not be operating and the engine may overheat. Also DTCs may set when the engine is operating with the drive belt removed.

3. The drive belt may cause a vibration. While the drive belt is removed, this is the best time to inspect the condition of the belt.

4. Inspecting of the fasteners can address the possibility that a wrong bolt, nut, spacer, or washer was installed.

5. Inspect the water pump shaft for being bent. Also, inspect the water pump bearings for smooth operation and play above acceptable tolerances. Compare the water pump with a known good water pump.

6. 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: Refer to Belt Dressing Notice in the Preface section. 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 |

Important: When removing the drive belt the water pump will not be operating and the engine may overheat.

1. Remove the drive belt. Refer to Drive Belt Replacement .
2. Operate the engine for no longer than 30 to 40 seconds.

Does the engine still make the vibration?

Go to Drive Belt Rumbling and Vibration Diagnosis

Go to Step 4

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 10 | -
6 | Inspect for incorrect, loose or missing fasteners. Did you find any of these conditions? | Go to Step 7 | Go to Step 8
7 |

Notice: Refer to Fastener Notice in the Preface section.

1. Tighten any loose fasteners. Refer to Fastener Tightening Specifications .
2. Replace incorrect or missing fasteners.

Did you complete the repair?

Go to Step 10

-

8 | Inspect for a bent water pump shaft. Refer to Water Pump Replacement . Did you find and correct the condition? | Go to Step 10 | Go to Step 9
9 | Inspect for bent or cracked brackets. Did you find and correct the condition? | Go to Step 10 | Go to Diagnostic Aids
10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3