| Table 1: | Drive Belt Chirping |
| Table 2: | Drive Belt Squeal |
| Table 3: | Drive Belt Whine |
| Table 4: | Drive Belt Rumbling |
| Table 5: | Drive Belt Vibration |
| Table 6: | Drive Belt Falls Off |
| Table 7: | Excessive Drive Belt Wear |
Definitions
The following noises are symptomatic noises of the accessory drive belt system.
Chirping
Chirping is a high pitched noise that is usually heard once per revolution of a pulley or a belt.
Chirping usually occurs on cold, damp mornings.
Squirt water onto the belt in order to verify that the noise is a chirping noise. The noise will momentarily stop.
Squeal
A squeal is a loud screeching noise.
A slipping belt causes a squeal. The noise occurs when a heavy load, such as an air conditioning compressor engagement, is applied to the belt. The heavy load may snap the throttle or slip on a seized pulley.
Multiple ribbed belts rarely cause a squeal.
Whine
A whine is a high pitched, continuous noise.
A failed component bearing may cause a whine.
Faint Cycle Rumbling
A faint cycle rumbling is a low frequency noise that is heard once per revolution of the belt.
Pilling
Pilling is 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 affected unless the buildup exceeds one third (1/3) of the belt groove depth.
Multiple-ribbed type drive belts wear evenly with their pulleys. Correct the condition if unusual wear is evident. The following diagnostic tables will aid in diagnosing drive belt system conditions.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Inspect for misalignment of the pulleys. Are any of the pulleys misaligned? | -- | ||
2 | Replace any misaligned pulleys. Is the chirp still present? | -- | System OK | |
3 | Inspect for bent or cracked brackets. Are there any bent or cracked brackets? | -- | ||
4 | Replace any bent or cracked brackets. Is the chirp still present? | -- | System OK | |
5 | Inspect for any loose or missing fasteners. Are there any loose or missing fasteners? | -- | ||
6 | Tighten any loose fasteners. Correctly install any missing fasteners. Refer to Fastener Tightening Specifications . Is the chirp still present? | -- | System OK | |
7 | Inspect for a bent pulley flange. Is the pulley flange bent? | -- | ||
8 | Replace the pulley flange. Is the chirp still present? | -- | System OK | |
9 | Inspect for severe pilling. Severe pilling exceeds 1/3 of the belt groove depth. Is there severe pilling? | -- | -- | |
10 | Replace the accessory drive belt. Refer to Drive Belt Replacement . Is the chirp still present? | -- | -- | System OK |
Step | Action | Value | Yes | No |
|---|---|---|---|---|
1 | Inspect for a misaligned pulley. Is a pulley misaligned? | -- | ||
2 | Inspect for incorrect belt length. Refer to Drive Belt Tensioner Diagnosis . Is the belt length correct? | -- | ||
3 | Repair or replace the components, as necessary. Is the repair complete? | -- | System OK | -- |
4 | Inspect for a malfunctioning drive belt tensioner. Refer to Drive Belt Tensioner Diagnosis . Is the tensioner malfunctioning? | -- | ||
5 | Inspect for correct pulley size. Are the pulleys the correct size? | -- | ||
6 | Inspect for seized bearings. Is there a seized bearing? | -- | System OK |
Step | Action | Value | Yes | No |
|---|---|---|---|---|
1 | Inspect for a worn accessory component bearing. Is a bearing making the noise? | -- | System OK | |
2 | Install new components, as necessary. Is the repair complete? | -- | System OK | -- |
Step | Action | Value | Yes | No |
|---|---|---|---|---|
1 | Inspect for severe pilling. Severe pilling exceeds more than 1/3 of the rib depth. Is there severe pilling? | -- | System OK | |
2 | Clean the drive belt pulleys. Are the drive belt pulleys clean? | -- | ||
3 | Install a new accessory drive belt. Is the repair complete? | -- | System OK | -- |
Step | Action | Value | Yes | No |
|---|---|---|---|---|
1 | Inspect for loose or missing fasteners. Are any fasteners loose or missing? | -- | ||
2 | Re-tighten or replace the fasteners, as necessary. Is the repair complete? | -- | System OK | -- |
3 | Inspect for damaged fan blades. Are there damaged fan blades? | -- | ||
4 | Replace the fan blades, as necessary. Refer to Fan Replacement in Engine Cooling. Is the replacement complete? | -- | System OK | -- |
5 | Inspect for a bent fan clutch or coolant pump shaft. Is the fan clutch or the coolant pump shaft bent? | -- | ||
6 | Replace the components, as necessary. Refer to Water Pump Replacement in Engine Cooling. Is the repair complete? | -- | System OK | -- |
7 | Inspect for bent or cracked brackets. Are the brackets bent or cracked? | -- | System OK | |
8 | Replace the brackets as necessary. Is the repair complete? | -- | System OK | -- |
Step | Action | Value | Yes | No |
|---|---|---|---|---|
1 | Inspect for a misaligned or a bent pulley. Are the pulleys misaligned? | -- | ||
2 | Replace any misaligned or bent pulleys. Does the drive belt continue to fall off? | -- | System OK | |
3 | Inspect for a bent or a cracked bracket. Are any of the brackets bent or cracked? | -- | ||
4 | Replace the damaged brackets. Does the drive belt continue to fall off? | -- | System OK | |
5 | Inspect for loose or missing fasteners. Are there any loose or missing fasteners? | -- | ||
6 | Replace any missing fasteners. Tighten the fasteners to specifications. Refer to Fastener Tightening Specifications . Does the drive belt continue to fall off? | -- | System OK | |
7 | Inspect for a misaligned power steering pump pulley. Is the power steering pump pulley misaligned? | -- | ||
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? | -- | System OK | |
9 | Inspect for a damaged drive belt. Is the drive belt damaged? | -- | ||
10 | Replace the drive belt. Refer to Drive Belt Replacement . Does the drive belt continue to fall off? | -- | System OK | |
11 | Inspect for a malfunctioning drive belt tensioner. Is the drive belt tensioner malfunctioning? | -- | ||
12 | Replace the drive belt tensioner. Does the drive belt continue to fall off? | -- | System OK | |
13 | Inspect for worn idler or tensioner pulley bearings. Are the idler or tensioner pulley bearings worn? | -- | -- | |
14 | Replace the worn bearings. Does the drive belt continue to fall off? | -- | -- | System OK |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Inspect the drive belt and the pulley. Determine 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? | -- | -- | |
2 | Replace the drive belt. Refer to Drive Belt Replacement . Is there still excessive wear in either outside groove of the drive belt? | -- | -- | System OK |
General Instructions
| • | Ensure that the drive belt is correctly installed on the pulley. |
| Verify that each groove on the drive belt rests inside a matching groove in the pulley. |
| • | When installing a new drive belt, observe the indicator on the tensioner. |
| A new drive belt should fall inside the illustrated range. |
| • | When installing a used drive belt, observe the indicator on the tensioner. |
| A used drive belt should fall inside the illustrated range. |
| • | The above illustration indicates incorrect installation of the drive belts. |
| Avoid mis-positioning the belt by one or more grooves. |
