Noise

Droning or periodic vibrations at particular engine speeds can be caused by the following:
^ Loose or stripped bolts: Replace or tighten bolts as required. Tighten all bolts to specification including fan blade-to-fan clutch (if equipped), fan clutch-to-water pump (if equipped), all bracket and accessory bolts and drive belt tensioner retaining bolts.
^ Drive belt flutter: Observe drive belt with engine running and transmission in PARK (NEUTRAL for manual transmission) with parking brake set. Slowly increase engine speed until noise/vibration/harshness condition occurs. If drive belt is vibrating more than 12.7 mm (0.5 inch), then drive belt flutter is occurring. Drive belt flutter is normally caused by external forces such as bent pulleys, worn accessories, excessive A/C head pressures or similar factors. To verify accessory drive is functioning properly, check automatic drive belt tensioner wear indicator marks to make sure drive belt is not worn and that the correct length drive belt is installed. Replace drive belt as required. If drive belt is correct and is in good condition, check automatic drive belt tensioner. Service components as required.
^ Binding or frozen automatic drive belt tensioner: Rotate automatic drive belt tensioner and check for a binding or frozen condition. Service as required. Check automatic drive belt tensioner.

^ Bent pulley: Inspect all pulleys for a wobbling condition. Service components as required.

NOTE: Look at the pulley grooves (not at the pulley flanges) for wobbling condition.

^ Worn accessories: Check accessories for smooth rotation and proper operation. Service components as required.

Rattling noise with A/C on can be caused by the following:
^ Automatic drive belt tensioner hitting the stops: Check wear indicator marks on drive belt tensioner and make sure drive belt is not worn and correct length drive belt is installed. Replace drive belt as required.
^ Excessive drive belt rideout: Although rare, the drive belt groove depth may vary enough to cause excessive drive belt tensioner actions. Try replacing the drive belt with a new drive belt.

Sharp metallic click with a chirp when A/C compressor clutch is engaged:
^ The click is caused by the A/C compressor clutch engagement and should be considered normal.
^ This click is sometimes accompanied by a clutch chirp. This should also be considered normal and not confused with drive belt chirp.

Loud drone or moan while turning the wheels:
^ This is usually an indication of low power steering fluid.
^ Check and refill the power steering fluid as required.

Muted ticking noise on cold weather start:
^ This can sometimes be heard with the hood (16612) open during a cold start.
^ It is caused by the drive belt label making contact with the backside of the pulleys and should be considered normal.

The frictional capability of the drive belt will be compromised if:
^ the drive belt tension is below specification.
^ there is any type of lubrication or belt dressing on the drive belt.

NOTE: The V-ribbed drive belt is dependent on friction to deliver power to a pulley. If the horsepower load of the accessories exceeds the drive belt frictional capability, a loud, continuous drive belt squeal will result.

Do not use any type of belt dressing, silicone spray or rubber conditioner on a V-ribbed drive belt.

The use of a lubricant may temporarily silence a squealing drive belt, but it does so by allowing the drive belt to slip in the pulleys. The squeal will eventually return and the drive belt will often be:
^ glazed.
^ damaged or destroyed.

NOTE: If the accessory drive system has been contaminated, all pulleys should be cleaned with a suitable solvent before installing a new drive belt.

Pulleys will also become contaminated by the lubricant and then will contaminate the replacement drive belt, reducing its frictional capability.

CAUTION: If drive belt chirp is present, determine the cause and correct it. Do not use any type of lubricant on the drive belt.

NOTE: V-ribbed serpentine drive belts are sensitive to pulley alignment. If a pulley is not in the same plane as the others, the drive belt may exhibit a periodic chirp. Sometimes a chirp will occur in a system that is perfectly aligned.

Removing and installing the same drive belt will often correct drive belt chirp permanently. Regardless of how the chirp is corrected, the vehicle should be allowed to idle for approximately 20 minutes with the accessories loaded down (headlamps, A/C system and other accessories, turned on). Recheck to make sure the chirp is corrected.

NOTE:
^ Water also acts as a lubricant but quickly evaporates. A vehicle just out of a car wash may exhibit drive belt squeal for a short period of time while the drive belt dries out. This is normal but the accessory load should be reduced (turn OFF A/C system and minimize power steering effort) until drive belt dries. This will prevent the drive belt from becoming glazed or damaged.
^ Squirting water (in small amounts) on the grooves of a noisy drive belt should temporarily change, reduce or eliminate the noise.

Using a squirt bottle or equivalent, squirt the grooves of the noisy drive belt.

If the water has no effect on the noise, the condition is being caused by something other than that drive belt.

NOTE: Incorrect drive belt installation may cause chirp or squeal.

Other possible causes of drive belt chirp include the following:
^ idler/tensioner pulley bearings
^ A/C compressor clutch (during engagement)
^ accessory bearings

Other possible causes of drive belt squeal include the following:
^ idler/tensioner pulley bearings
^ accessory bearings

Check the drive belts for proper routing, seating and for wear.

CAUTION: Incorrect drive belt installation will cause excessive drive belt wear and may cause the drive belt to come off the drive pulleys.

Check the drive belts and pulleys for contamination antifreeze, belt dressing, undercoating or other possible causes.
^ Antifreeze contamination: A thorough rinsing of belts and pulleys with clean water should restore the frictional capability of the drive belts.
^ Other contaminants: Remove and discard drive belt. Clean all pulleys with a suitable solvent and install a new drive belt.

Check the power steering pump pulley (3A733). It should be flush with the end of the power steering pump shaft within +/- 0.25 mm (0.010 inch).

Check all pulleys (except crankshaft pulley (6312)) and accessories for smooth, free operation. Service any components as required.