Diagnostic information
Engine vibration can cause rattling noise from body components or other parts.
The drive belt may have properties that cannot be determined by visual inspection. Sometimes replacing the belt may be the only way to confirm that the cause is a faulty belt.
If the diagnostic chart is completed after replacing the drive belt, but the noise is only present when the drive belt is installed, the noise may be caused by an accessory drive component, such as the air conditioning compressor. Varying the load on each accessory drive component in turn should help isolate the component causing the noise.
Description of the test
The item numbers below are the step numbers in the diagnostic chart.
- Confirms the existence of the symptom during diagnosis. Noise may be caused by other components of the vehicle.
- Confirms that the accessory drive belt is causing the noise. Drive belt noise is often confused with internal engine noise due to the similarity in description. Removing the drive belt and running the engine for a while can confirm or deny that the noise is related to the drive belt.
- Inspecting the drive belt ensures that it is not the cause of the noise. Small cracks in the ribs of the drive belt do not cause noise and are not, in themselves, a reason to replace the belt. Belt delamination can be identified by a layer of separation of the belt and can be seen on the side edges of the belt or felt as bulges under the belt.
- A small amount of sticking and inclusions is normal and is considered acceptable. When the amount of pilling reaches a significant level (33% of the belt groove depth), the belt does not have a smooth running surface and must be replaced.
Diagnostic table
Definition: Accessory drive belt rattle can be defined as a low-pitched knocking, thumping, or thumping noise heard only at or above idle speed, once per revolution of the drive belt or a specific accessory drive component. Drive belt rattle is caused by one of the following:
- balls or stripes in the grooves of the drive belt;
- delamination of the drive belt or
- damage or malfunction of the drive belt.
Note: Pilling is the formation of small balls (growths) or stripes of rubber in the grooves of the drive belt caused by the accumulation of rubber dust.
| Step | Operation | Values | Yes | No |
| 1 |
Have you reviewed the information provided in the Symptoms section and performed the required checks?
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-
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Jump to operations 2
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Go to item Symptoms
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| 2 |
Confirm customer complaint. Is there a rumbling noise?
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-
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Jump to operations 3
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See diagnostic recommendations in this section
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| 3 |
Is the rumbling sound still present?
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-
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The drive system of the units is in order.
Go to "Symptoms" and start diagnostics again
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Jump to operations 4
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| 4 |
Inspect the accessory drive belt for damage, delamination, or areas with missing ribs.
Are there any damages, delaminations or missing ribs?
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-
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Jump to operations 7
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Jump to operations 5
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| 5 |
Inspect the accessory drive belt for severe pilling (exceeding 33% of belt groove depth).
Is there any serious pilling detected?
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-
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Jump to operations 6
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Jump to operations 5
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| 6 |
Clean the drive belt with a suitable wire brush and reinstall it on the engine, see. Section 1B, Engine Mechanical System - 2.0 Diesel.
Is the renovation completed?
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-
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Jump to operations 8
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-
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| 7 |
Install a new accessory drive belt, see. Section 1B, Engine Mechanical System - 2.0 Diesel.
Has the accessory drive belt been replaced?
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-
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Jump to operations 8
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-
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| 8 |
If required, reinstall the accessory drive belt and operate the system to confirm completion of the repair.
Has the rumbling noise been eliminated?
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-
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The drive system of the units is in order
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Jump to "Symptoms" and restart the diagnostics
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