| Table 1: | Chirping |
| Table 2: | Drive Belt Squeal |
| Table 3: | Drive Belt Whine |
| Table 4: | Drive Belt Rumbling |
| Table 5: | Drive Belt Falls Off |
| Table 6: | Excessive Wear in Either Outside Groove of Drive Belt |
The following are symptomatic noises of the accessory drive belt system:
- Chirping:
- Squeal:
- 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:
| • | 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. |
| • | 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. |
| • | 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.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
DEFINITION: A high pitched noise usually heard once per revolution of a pulley or belt. It is usually heard at idle and is most common on cold damp mornings. Squirting water on a chirping belt will usually cause the noise to momentarily go away. | ||||
1 | Inspect for misalignment of the pulleys. Are any of the pulleys misaligned? | -- | Go to Step 2 | Go to Step 3 |
2 | Replace any misaligned pulleys. Is the chirp still present? | -- | Go to Step 3 | System OK |
3 | Inspect for bent or cracked brackets. Are there any bent or cracked brackets? | -- | Go to Step 4 | Go to Step 5 |
4 | Replace any bent or cracked brackets. Is the chirp still present? | -- | Go to Step 5 | System OK |
5 | Inspect for any loose or missing fasteners. Are there any loose or missing fasteners? | -- | Go to Step 6 | Go to Step 7 |
6 | Tighten any loose fasteners and properly install any missing fasteners. Refer to Fastener Tightening Specifications. Is the chirp still present? | -- | Go to Step 7 | System OK |
7 | Inspect for a bent pulley flange. Is the pulley flange bent? | -- | Go to Step 8 | Go to Step 9 |
8 | Replace the pulley flange. Is the chirp still present? | -- | Go to Step 9 | System OK |
9 | Inspect for severe pilling, exceeding 1/3 of the belt groove depth. Is there severe pilling? | -- | Go to Step 10 | -- |
10 | Replace the accessory drive belt. Refer to Drive Belt Replacement. Is the chirp still present? | -- | -- | System OK |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Inspect for a misaligned pulley. Is there a pulley misaligned? | -- | Go to Step 3 | Go to Step 2 |
2 | Inspect for incorrect belt length, refer to Accessory Drive Tensioner Diagnosis. Is the belt length correct? | -- | Go to Step 4 | Go to Step 3 |
3 | Repair or install new components as necessary. Is the repair complete? | -- | System OK | -- |
4 | Inspect for a malfunctioning drive belt tensioner, refer to Accessory Drive Tensioner Diagnosis. Is the tensioner malfunctioning? | -- | Go to Step 3 | Go to Step 5 |
5 | Inspect for correct pulley size. Are the pulleys the correct size? | -- | Go to Step 6 | Go to Step 3 |
6 | Inspect for seized bearings. Is there a seized bearing? | -- | Go to Step 3 | System OK |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Inspect for a worn accessory component bearing. Is a bearing making the noise? | -- | Go to Step 2 | System OK |
2 | Install new parts as necessary. Is the repair complete? | -- | System OK | -- |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Inspect for severe pilling. Is there severe pilling of more than 1/3 of the rib depth? | -- | Go to Step 2 | System OK |
2 | Install a new accessory drive belt. Is the repair complete? | -- | System OK | -- |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Inspect for a misaligned or a bent pulley. Are the pulleys misaligned? | -- | Go to Step 2 | Go to Step 3 |
2 | Replace any misaligned or bent pulleys. Does the drive belt continue to fall off? | -- | Go to Step 3 | System OK |
3 | Inspect for a bent or a cracked bracket. Are any of the brackets bent or cracked? | -- | Go to Step 4 | Go to Step 5 |
4 | Replace the damaged brackets. Does the drive belt continue to fall off? | -- | Go to Step 5 | System OK |
5 | Inspect for loose or missing fasteners. Are there any loose or missing fasteners? | -- | Go to Step 6 | Go to Step 7 |
6 | Replace any missing fasteners and tighten to specifications. Refer to Fastener Tightening Specifications. Does the drive belt continue to fall off? | -- | Go to Step 7 | System OK |
7 | Inspect for a misaligned power steering pump pulley. Is the power steering pump pulley misaligned? | -- | Go to Step 8 | Go to Step 9 |
8 | Realign or replace the power steering pump pulley. Refer to Power Steering Pump Replacement in Power Steering. Does the drive belt continue to fall off? | -- | Go to Step 9 | System OK |
9 | Inspect for a damaged drive belt. Is the drive belt damaged? | -- | Go to Step 10 | Go to Step 11 |
10 | Replace the drive belt. Refer to Drive Belt Replacement. Does the drive belt continue to fall off? | -- | Go to Step 11 | System OK |
11 | Inspect for a malfunctioning drive belt tensioner. Is the drive belt tensioner malfunctioning? | -- | Go to Step 12 | Go to Step 13 |
12 | Replace the drive belt tensioner. Refer to Drive Belt Tensioner Replacement. Does the drive belt continue to fall off? | -- | Go to Step 13 | System OK |
13 | Inspect for worn idler or tensioner pulley bearings. Are the idler or tensioner pulley bearings worn? | -- | Go to Step 14 | -- |
14 | Replace the worn bearings. Does the drive belt continue to fall off? | -- | -- | System OK |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Inspect to see if the ribs in the drive belt do not match the grooves in the pulley. Do the ribs in the drive belt match the grooves in the pulley? | -- | -- | Go to Step 2 |
2 | Replace the accessory drive belt. Refer to Drive Belt Replacement. Is there still excessive wear in either outside groove of the drive belt? | -- | -- | System OK |
