| Table 1: | Drive Belt Chirping |
| Table 2: | Drive Belt Squeal |
| Table 3: | Drive Belt Whine |
| Table 4: | Drive Belt Rumbling |
| Table 5: | Drive Belt Falls Off |
| Table 6: | Drive Belt Vibration Problems |
| Table 7: | Excessive Wear in Either Outside Groove of Drive Belt |
Drive Belt Noise
Drive belt noise may be described as a thumping noise heard at, or just above idle speed, as a result of drive belt pilling. In a single-belt drive, drive belt pilling occurs when small particles of drive belt material separate from the drive belt grooves, and form small balls or pills in the drive belt grooves. While some drive belt pilling is normal, excessive pilling can cause a thump or knocking as the pills pass over various drive belt pulleys. This causes the drive belt to repeatedly jump off of and slap onto the drive belt pulley.
The thump or knocking noise easily misdiagnoses as an engine noise. In order to diagnose drive belt pilling, adhere to the following procedure:
- Remove the drive belt.
- Run the engine for no more than 30 to 40 seconds, in order to confirm that the engine noise disappears.
- Inspect the power steering pulley for proper alignment.
- Inspect all other pulleys for excess paint, debris or pills in the grooves.
- Clean the pulleys with a wire brush, as necessary.
Definitions
The following are symptomatic noises of the drive belt system:
Chirping
| • | A high pitched noise that is usually heard once per revolution of a drive belt pulley or a drive belt. |
| • | It is most common on cold, damp mornings. |
| • | Verify this condition by squirting water onto the drive belt. The noise will momentarily stop. |
Squeal
| • | A loud screeching noise that is caused by a slipping drive belt (this is unusual for a multi-ribbed drive belt). |
| • | The noise occurs when a heavy load is applied to the drive belt, such as an air conditioning compressor engagement, snapping the throttle, or slipping on a seized drive belt pulley. |
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 drive belt.
Pilling
| • | The random accumulation of rubber dust in the bottom of the multi-ribbed drive belt grooves. |
| • | A small amount of pilling is normal. |
| • | Operation of the drive belt system will not be affected unless the buildup exceeds one third (1/3) of the drive belt groove depth. |
Multi-ribbed drive belts wear evenly with their drive belt pulleys. Unusual wear indicates a correction is needed.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Check for misalignment of the drive belt pulleys. Are any of the drive belt pulleys misaligned? | -- | Go to Step 2 | Go to Step 3 |
2 | Replace any misaligned drive belt pulleys. Is the chirp still present? | -- | Go to Step 3 | System OK |
3 | Check 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 | Check 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. Is the chirp still present? | -- | Go to Step 7 | System OK |
7 | Check for a bent drive belt pulley flange. Is the drive belt pulley flange bent? | -- | Go to Step 8 | Go to Step 9 |
8 | Replace the drive belt pulley flange. Is the chirp still present? | -- | Go to Step 9 | System OK |
9 | Check for severe pilling, exceeding 1/3 of the drive belt groove depth. Is there severe pilling? | -- | Go to Step 10 | -- |
10 | Replace the drive belt. Is the chirp still present? | -- | -- | System OK |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Check for an incorrect routing of the drive belt. Is the drive belt routed correctly? | -- | Go to Step 3 | Go to Step 2 |
2 | Refer to the drive belt routing. Is there still a drive belt squeal? | -- | Go to Step 3 | System OK |
3 | Check for a misaligned drive belt pulley. Is there a drive belt pulley misaligned? | -- | Go to Step 5 | Go to Step 4 |
4 | Check for incorrect belt length. Is the belt length correct? | -- | Go to Step 6 | Go to Step 5 |
5 | Repair or install new parts as necessary. Is the repair complete? | -- | System OK | -- |
6 | Check for a malfunctioning drive belt tensioner. Is the drive belt tensioner malfunctioning? | -- | Go to Step 5 | Go to Step 7 |
7 | Check for correct drive belt pulley size. Are the drive belt pulleys the correct size? | -- | Go to Step 8 | Go to Step 5 |
8 | Check for seized bearings. Are there any seized bearings? | -- | Go to Step 5 | System OK |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Check for a worn 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 | Check for severe drive belt pilling. Is there severe pilling of more than 1/3 of the drive belt rib depth? | -- | Go to Step 2 | System OK |
2 | Install a new drive belt. Is the repair complete? | -- | System OK | -- |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Check for a misaligned or a bent drive belt pulley. Are the drive belt pulleys misaligned? | -- | Go to Step 2 | |
2 | Replace any misaligned or bent drive belt pulleys. Does the drive belt continue to fall off? | -- | Go to Step 3 | System OK |
3 | Check 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 | Check 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. Does the drive belt continue to fall off? | -- | Go to Step 7 | System OK |
7 | Check for a misaligned power steering pump drive belt pulley. Is the power steering pump drive belt pulley misaligned? | -- | Go to Step 8 | Go to Step 9 |
8 | Realign or replace the power steering pump drive belt pulley. Refer to Power Steering Gear and Pump. Does the drive belt continue to fall off? | -- | Go to Step 9 | System OK |
9 | Check for a damaged drive belt. Is the drive belt damaged? | -- | Go to Step 10 | Go to Step 11 |
10 | Replace the drive belt. Does the drive belt continue to fall off? | -- | Go to Step 11 | System OK |
11 | Check 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. Does the drive belt continue to fall off? | -- | Go to Step 13 | System OK |
13 | Check for worn idler or tensioner drive belt pulley bearings. Are the idler or tensioner drive belt 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 | Check for loose or missing fasteners. Are there loose or missing fasteners? | -- | Go to Step 2 | Go to Step 3 |
2 | Retighten or replace fasteners as necessary. Is the repair complete? | -- | System OK | -- |
3 | Check for a bent coolant pump shaft. Is the coolant pump shaft bent? | -- | Go to Step 4 | Go to Step 5 |
4 | Replace as necessary. Refer to Cooling and Radiator. Is the repair complete? | -- | System OK | -- |
5 | Check for bent or cracked brackets. Are there bent or cracked brackets? | -- | Go to Step 6 | System OK |
6 | Replace the brackets as necessary. Is the repair complete? | -- | System OK | -- |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Check to see if the ribs in the drive belt do not match the grooves in the drive belt pulley. Do the ribs in the drive belt match the grooves in the drive belt pulley? | -- | -- | Go to Step 2 |
2 | Replace the drive belt. Is there still excessive wear in either outside groove of the drive belt? | -- | -- | System OK |
