Definitions
The following are symptomatic noises of the accessory drive belt system:
- Chirping:
| • | A high pitched noise that is usually heard once per revolution
of a pulley or a belt. |
| • | It is most common on cold, damp mornings. |
| • | Verify this condition by squirting water onto the belt. The noise
will momentarily stop. |
- Squeal:
| • | A loud screeching noise that is caused by a slipping belt (this
is unusual for a multiple ribbed belt). |
| • | The noise occurs when a heavy load is applied to the belt, such
as an air conditioning compressor engagement, snapping the throttle, or slipping
on a seized pulley. |
- Knocking:
| • | A low pitch tapping noise caused by belt misalignment. |
| • | This noise occurs on cold start-up at idle. |
- Whine: A high pitched continuous noise that may be caused by a
failed component bearing.
- Faint Cycle Rumbling: A low frequency noise heard once per revolution
of the belt.
- Pilling:
| • | The random accumulation of rubber dust in the bottom of the multi-ribbed
belt grooves. |
| • | A small amount of pilling is normal. |
| • | Operation of the drive belt system will not be effected unless
the buildup exceeds one third (1/3) of the belt groove depth. |
Multiple ribbed, accessory drive belts wear evenly with their pulleys.
Unusual wear indicates a correction is needed. The following diagnostic tables
will aid in diagnosing drive belt system problems.
