Drive Belt: Testing and Inspection

DEFINITIONS
The following are symptomatic noises of the drive belt system:

Chirping
The following items are indications of 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
The following items are indications of squeal:
- A loud screeching noise that is caused by a slipping belt (this is unusual for a belt with multiple ribs).
- 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.

Whine
A high pitched continuous noise that may be caused by a failed bearing.

Faint Cycle Rumbling
A low frequency noise heard once per revolution of the drive belt.

Pilling
The following items are indications of 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 type 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 conditions.





Drive Belt Diagnosis





Drive Belt Squeal





Drive Belt Whine





Drive Belt Rumbling





Drive Belt Vibration








Drive Belt Falls Off





Drive Belt Diagnosis

GENERAL INSTRUCTIONS
The following graphics illustrate the correct way to route the drive belt over the pulleys, and some examples of incorrect belt placement.





1. Observe the drive belt correctly installed on the pulley.
Each groove on the drive belt rests inside a matching groove in the pulley.





2. When installing a new drive belt, observe the indicator on the tensioner.
A new drive belt should fall inside this range.





3. When installing a used drive belt, observe the indicator on the tensioner.
A used drive belt should fall inside this range.





4. Observe these incorrectly installed drive belts:
Avoid mis-positioning the belt by one or more grooves.