Symptom Chart - Noise, Vibration and Harshness (NVH)

WARNING: This page is about a different car, the 2009 Mercury Sable, 2009 Ford Taurus X, and 2009 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Noise, vibration and harshness (NVH) symptoms should be identified using the diagnostic tools that are available. For a list of these tools, an explanation of their uses and a glossary of common terms, refer to NOISE, VIBRATION AND HARSHNESS article. Since it is possible any one of multiple systems may be the cause of a symptom, it may be necessary to use a process of elimination type of diagnostic approach to pinpoint the responsible system. If this is not the causal system for the symptom, refer back to NOISE, VIBRATION AND HARSHNESS article for the next likely system and continue diagnosis.

SYMPTOM CHART - NOISE, VIBRATION AND HARSHNESS (NVH)

Condition	Possible Sources	Action
Steering system cold start noise	Blockage in the power steering fluid reservoir caused by power steering fluid contamination	NOTE: Some noise during an extremely cold start (-12.2°C [-10°F]) is normal and should improve as the steering system warms up (usually within 60 seconds). With the engine running, CHECK for bubbling fluid flow in the reservoir. If bubbling fluid flow is not evident, INSTALL a new power steering fluid reservoir. REFER to POWER STEERING article. FLUSH the power steering system as necessary. REFER to Power Steering System Flushing .
	Air in the steering hydraulic system (aerated fluid)	CHECK for leaks in the system. REFER to Power Steering Leak Test in Component Tests. PURGE the air from the system. REFER to Power Steering System Purging .
Steering grunt or shudder - occurs when turning into or out of a turn at low speeds (temperature sensitive)	Air in the steering hydraulic system (aerated fluid)	CHECK for leaks in the system. REFER to Power Steering Leak Test in Component Test. PURGE the air from the system. REFER to Power Steering System Purging .
	Steering gear or power steering hoses	Go to Steering Gear Grunt/Shudder Component Test.
Steering system clonk - hydraulic knocking sound	Air in the steering hydraulic system (aerated fluid)	NOTE: Some amount of clonk noise is considered acceptable. If in doubt of the acceptability, compare to another vehicle. CHECK for leaks in the system. REFER to Power Steering Leak Test Component Test. PURGE the air from the system. REFER to Power Steering System Purging .
Power steering pump moan - loud humming noise occurs when the steering wheel is rotated to the stop position. Produces a 120-600 Hz frequency that changes with RPM	Low fluid	CHECK the fluid level. FILL as necessary. REFER to Power Steering System Filling .
	Air in the steering hydraulic system (aerated fluid)	CHECK for leaks in the system. REFER to Power Steering Leak Test Component Test. PURGE the air from the system. REFER to Power Steering System Purging . If a pump moan still exists, INSTALL a new power steering pump. REFER to POWER STEERING article.
	Power steering fluid reservoir filter is blocked or damaged	INSPECT the reservoir. FLUSH or INSTALL a new reservoir as necessary.
	Power steering line/hose grounded to chassis	INSPECT the power steering lines/hoses. REPAIR as necessary.
	Loose power steering pump bolts	TIGHTEN bolts to specification. REFER to POWER STEERING article.
	Steering gear isolators	INSPECT the isolators for wear or damage. REPAIR as necessary.
Steering gear clunk - occurs only while cornering over a bump (can be temperature sensitive)	Steering gear	INSPECT the steering gear for loose mounting bolts. TIGHTEN to specification as necessary. REFER to POWER STEERING article.
Feedback (rattle, chuckle or knocking noise in the steering gear) - roughness is felt in the steering wheel when the vehicle is driven over rough surfaces	Steering column shaft/coupling joints damaged or worn	INSTALL a new steering column shaft. REFER to STEERING COLUMN article.
	Loose, damaged or worn tie-rod ends	INSPECT and INSTALL new tie-rod ends as necessary. Go to Steering Linkage in Component Tests.
	Steering gear insulators or mounting bolts loose or damaged	TIGHTEN the bolts to specification or INSTALL new bolts as necessary. REFER to POWER STEERING article.
	Steering column shaft/coupling bolts are loose	TIGHTEN the bolts to specification. REFER to STEERING COLUMN article.
	Steering column damaged or worn	REPAIR or INSTALL a new steering column as necessary. REFER to STEERING COLUMN article.
	Loose suspension bushings, bolts or ball joints	INSPECT the suspension components. REFER to SUSPENSION SYSTEM - GENERAL INFORMATION article for the suspension diagnosis and testing.
Accessory drive belt squeal/chirp - when rotating the steering wheel from stop-to-stop	Engine accessory drive system	REFER to ENGINE SYSTEM - GENERAL INFORMATION article to continue accessory drive system diagnosis.
Power steering hiss or whistle	Steering column shaft/coupling-to-steering gear is binding or misaligned	REPAIR or INSTALL a new steering column shaft as necessary. REFER to STEERING COLUMN article.
	Grounded or loose steering column boot at the dash panel	REPAIR as necessary.
	Damaged or worn steering gear input shaft and valve	REPAIR or INSTALL a new steering gear as necessary. REFER to POWER STEERING article.
	Power steering pump low relief pressure	Go to Pinpoint Test D .
	Restricted power steering lines/hoses	Go to Pinpoint Test D .
Steering column rattle	Loose bolts or attaching brackets	TIGHTEN the bolts to specification.
	Loose, worn or insufficiently lubricated column bearings	LUBRICATE bearings or INSTALL new steering column bearings or steering column as necessary. REFER to STEERING COLUMN article.
	Steering shaft insulators damaged or worn	INSTALL new insulators. REFER to STEERING COLUMN article.
	Steering column shaft/coupling compressed or extended	INSPECT the rubber spider coupling for damage. INSTALL a new steering column shaft. REFER to STEERING COLUMN article.
Steering gear squeak	Incorrect power steering fluid in system	If incorrect power steering fluid is suspected, FLUSH the power steering system. REFER to Power Steering System Flushing . If noise persists after system flush, INSTALL a new steering gear. REFER to POWER STEERING article.
	Steering gear rotary seal	NOTE: Verify that the steering gear is the source of the noise. It may be necessary to replicate the customer operating conditions (fluid temperature, turning rate of steering wheel) to get the squeak to reoccur. INSTALL a new steering gear as necessary. REFER to POWER STEERING article.
	Stone shield (if equipped)	VERIFY that the stone shield is correctly installed and that it is not making contact with the steering shaft. REPOSITION stone shield or INSTALL a new stone shield as necessary.
Steering column squeak, cracks or grinds	Insufficiently lubricated steering shaft bushings	LUBRICATE the steering shaft and shaft tube seals.
	Loose or misaligned steering column shrouds	TIGHTEN or ALIGN the steering column shrouds.
	Steering wheel rubbing against steering column shrouds	REPOSITION the steering column shrouds.
	Upper or lower bearing sleeves out of position	REPOSITION the bearing sleeves.
Power steering pump noisy	Power steering pump	INSTALL a new power steering pump as necessary. REFER to POWER STEERING article.
Power steering pump relief noise	Power steering fluid flow into the bypass valve of the pump valve housing, with fluid temperature below 54°C (130°F)	Acceptable condition.
Power steering pump whine noise	Aerated fluid	CHECK for a leak in the system. REFER to Power Steering Fluid Leak Test in Component Test. PURGE the air from the system. REFER to Power Steering System Purging .
	Damaged power steering pump	INSTALL a new power steering pump as necessary. REFER to POWER STEERING article.
Shimmy	Loose, worn or damaged tie rod	Go to Steering Linkage in Component Test.