Symptom Charts - NVH: Notes

WARNING: This page is about a different car, the 2008 Mercury Mariner and 2008 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: 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 Charts - NVH

Condition	Possible Sources	Action
Axle howling or whine - front or rear axle	Axle lubricant low	CHECK the lubricant level. FILL the axle to specification.
	Axle housing damage	INSPECT the axle housing for damage. REPAIR or INSTALL a new axle as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
	Damaged or worn wheel hub bearings	CHECK for abnormal wheel hub bearing play or roughness. REFER to FRONT SUSPENSION article or REAR SUSPENSION article.
	Damaged or worn differential ring and pinion	INSPECT and INSTALL a new axle as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
	Damaged or worn differential side or pinion bearings	INSPECT and INSTALL a new axle as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
Driveline clunk - loud clunk when shifting from reverse to drive	Incorrect axle lubricant level	CHECK the lubricant level. FILL the axle to specification.
	Excessive backlash in the axle	CHECK the axle backlash. INSTALL a new axle as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
	Damaged or worn pinion bearings	INSTALL a new axle as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
	Damaged or worn U-joints	INSPECT the U-joints for wear or damage. INSTALL new U-joints or driveshaft as necessary. REFER to DRIVESHAFT article.
Driveline clunk - occurs as the vehicle starts to move forward following a stop	Worn driveshaft CV joint or U-joints with excessive play	INSPECT the CV joint and U-joints for a worn condition. INSTALL a new driveshaft or U-joints as necessary. REFER to DRIVESHAFT article.
	Loose rear axle mount	CHECK the axle for loose bolts. TIGHTEN to specification. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
Driveline clunk (Front Wheel Drive (FWD) vehicles) - occurs during acceleration or from cruise to coast/deceleration	Damaged or worn inner CV joint	INSPECT the inner CV joint and boot. INSTALL a new CV joint as necessary. REFER to FRONT DRIVE HALFSHAFTS article.
Clicking, popping or grinding - occurs while the vehicle is turning	Inadequate or contaminated lubrication in the CV joints	CHECK the CV boots and joints for wear or damage. INSTALL new components as necessary. REFER to FRONT DRIVE HALFSHAFTS article.
	Another component contacting the halfshaft	CHECK the halfshafts and the area around the halfshafts. REPAIR as necessary.
High pitched chattering - noise from the rear axle when the vehicle is turning	Incorrect or contaminated lubricant	CHECK the vehicle by driving in tight circles (5 clockwise, 5 counterclockwise). FLUSH and REFILL with the specified rear axle lubricant and friction modifier as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article,
	Damaged or worn differential (differential side gears and pinion gears)	INSTALL a new axle as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article for the rear axle.
Buzz - buzzing noise is the same at cruise or coast/deceleration	Incorrect driveline angles	CHECK for correct driveline angles. REPAIR as necessary. REFER to Driveline Angle Measurement .
Rumble or boom - noise occurs at coast/deceleration, usually driveshaft speed-related and noticeable over a wide range of speeds	Driveshaft is out-of-balance	CHECK the driveshaft for damage, missing balance weights or undercoating. REFER to DRIVESHAFT BALANCING - USING THE MASTERTECH® Series MTS 4000 Driveline Balance and NVH Analyzer (Vetronix) .
	U-joints are binding or seized	ROTATE the driveshaft and CHECK for rough operation or seized U-joints. INSTALL new U-joints or driveshaft as necessary. REFER to DRIVESHAFT article.
Grunting - normally associated with a shudder experienced during acceleration from a complete stop	Driveshaft CV joint binding	CLEAN the CV joint and INSTALL a new driveshaft as necessary. REFER to DRIVESHAFT article.
	Loose rear axle mount bolts or suspension fasteners	INSPECT the rear suspension and axle. TIGHTEN the fasteners to specification. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
Howl - can occur at various speeds and driving conditions. Affected by acceleration and deceleration	Incorrect ring and pinion contact, incorrect bearing preload or gear damage	INSPECT and INSTALL a new axle as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
Chuckle - heard at coast/deceleration. Also described as a knock	Incorrect ring and pinion contact or damaged teeth on the coast side of the ring and pinion	INSPECT and INSTALL a new axle as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
Knock - noise occurs at various speeds. Not affected by acceleration or deceleration	Gear tooth damage to the drive side of the ring and pinion	INSTALL a new axle as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
Scraping noise - a continuous low pitched noise starting at low speeds	Worn or damaged pinion bearings	INSTALL a new axle as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
Driveline shudder - occurs during acceleration from a slow speed or stop	Rear drive axle assembly mispositioned	CHECK the axle mounts and the rear suspension for damage or wear. REPAIR as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
	Loose rear axle bolts	CHECK the rear axle for loose bolts. TIGHTEN the bolts to specification. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
	Driveline angles out of specification	CHECK for correct driveline angles. REFER to Driveline Angle Measurement .
	U-joints binding or seized	ROTATE the driveshaft and CHECK for rough operation or seized U-joints. INSTALL new U-joints or driveshaft as necessary. REFER to DRIVESHAFT article.
	Binding or damaged driveshaft CV joint	INSPECT the driveshaft CV joint and coupling shaft for wear or damage. INSTALL a new driveshaft as necessary. REPAIR as necessary. REFER to DRIVESHAFT article.
Driveline vibration - occurs at cruising speeds	Worn U-joints	CHECK for wear or incorrect seating. INSTALL new U-joints or driveshaft as necessary. REFER to DRIVESHAFT article.
	Worn or damaged driveshaft center bearing support	CHECK the insulator for damage or wear. ROTATE the driveshaft and CHECK for rough operation. INSTALL a new driveshaft as necessary. REFER to DRIVESHAFT article.
	Loose axle pinion flange bolts	INSPECT the axle pinion flange. TIGHTEN the pinion flange bolts to specification. REFER to DRIVESHAFT article.
	Excessive axle pinion flange runout	CARRY OUT a runout check. REPAIR as necessary. REFER to REAR DRIVE AXLE/DIFFERENTIAL article.
	Driveshaft is out-of-balance	CHECK the driveshaft for damage, missing balance weights or undercoating. CHECK the driveshaft balance. CARRY OUT a driveline vibration test. REFER to Driveshaft Runout and Balancing .
	Binding or damaged driveshaft CV joint	INSPECT the driveshaft CV joint for wear or damage. INSTALL a new driveshaft as necessary. REFER to DRIVESHAFT article.
	Excessive driveshaft runout	CARRY OUT a runout check. REFER to Driveshaft Runout and Balancing .
	Driveline angles out of specification	CHECK for correct driveline angles. REPAIR as necessary. REFER to Driveline Angle Measurement .
	Incorrectly seated CV joint in the wheel hub	CHECK the outer CV joint for correct seating into the hub. REPAIR as necessary. REFER to FRONT DRIVE HALFSHAFTS article for the front CV joints or REAR DRIVE HALFSHAFTS article for the rear CV joints.