Diagnostic Information
Auxiliary drive components such as the A/C compressor or alternator can affect engine vibration.
To help isolate the component causing the noise, vary the load on each accessory drive component in turn and record the effect on vibration, if any.
Description of the test
The item numbers below are the step numbers in the diagnostic table.
- Confirms the existence of a symptom at the time of diagnosis. Noise may be caused by other vehicle components.
- Confirms that the accessory drive belt is causing the noise. Drive belt rumble is often confused with internal engine noise due to the similarity in the description. If you remove the drive belt and let the engine run for a bit, you can confirm or deny that the noise is related to the drive belt.
- The vibration may be caused by the drive belt. It is much easier to inspect the drive belt when it is removed.
- Inspection of fasteners can eliminate the possibility that the wrong fastener was installed.
- This step should only be performed if the coolant pump is belt driven. Inspect the water pump for bent shaft. Also check the coolant pump bearings for smooth rotation and no excessive play. Compare the coolant pump with a known good pump.
- Bent, cracked, or loose accessory drive component brackets can place additional stress on the accessory components, causing them to vibrate.
Diagnostic table
Definition: Drive belt vibration can be defined as bouncing, shaking or rattling. Drive belt vibration usually manifests itself as follows:
- vibration depends on engine speed or
- vibration is sensitive to the load of the accessory drive system.
| Step | Operation | Values | Yes | No |
| 1 |
Have you reviewed the information in the section "Symptoms", and performed the required checks?
|
-
|
Go to operation 2
|
Go to item Symptoms
|
| 2 |
Acknowledge the customer's complaint. Is there a rumbling noise?
|
-
|
Go to operation 3
|
See diagnostic advice in this section
|
| 3 |
Does vibration noise persist?
|
-
|
The drive system of the aggregates is in order.
Go to "Symptoms" and restart diagnostics
|
Go to operation 4
|
| 4 |
Inspect the accessory drive belt for damage, wear, build-up of dirt, or missing ribs.
Are there any damage, wear, buildup of dirt or missing fins?
|
-
|
Go to operation 5
|
Go to operation 6
|
| 5 |
Install a new accessory drive belt, see Section 1B, Engine Mechanical - 2.0 Diesel.
Has the accessory drive belt been replaced?
|
-
|
Go to operation 9
|
-
|
| 6 |
Inspect for correct installation, looseness, missing or damaged fasteners.
Are the wrong, loose, missing or damaged fasteners found?
|
-
|
Jump to Operation 7
|
Jump to operation 8
|
| 7 |
Tighten all loose fasteners to the correct torque to specifications.
Replace any incorrect or missing fasteners.
Has the repair been completed?
|
-
|
Go to operation 9
|
-
|
| 8 |
Inspect accessory drive component mounting brackets for kinks, cracks, or damage.
Bent brackets found and repaired?
|
-
|
Go to operation 9
|
See diagnostic advice in this section
|
| 9 |
If required, reinstall the accessory drive belt and operate the system to confirm repair is complete.
Vibration fixed?
|
-
|
The drive system of the aggregates is in order
|
See diagnostic advice in this section
|