Symptom Chart - NVH

WARNING: This page is about a different car, the 2017 Lincoln Navigator and 2017 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

Condition	Possible Sources	Action
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 . 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 for the next likely system and continue diagnosis.
Grinding noise during 4WD system engagement, especially at high speeds	Front halfshaft speeds not turning at the same speed Transfer case clutch	GO to Pinpoint Test C .
Straightline driveline wind-up	Unmatched tire sizes Unequal amounts of tire wear Unequal tire inflation pressures Unmatched front and rear axle ratios	GO to Pinpoint Test G .
The front axle makes noise in 2H mode only and generally under heavy throttle	Vacuum leaks Vacuum lines Vacuum check valves Vacuum reservoir IWE solenoid IWE	GO to Pinpoint Test H .
The transfer case makes noise	Tire inflation pressure Tire and wheel size	MAKE SURE that all tires and wheels are the same size and the inflation pressures are correct.
Tire tread wear		CHECK tire tread wear to see if there is more than 1.6 mm (0.062 in) or 2/32 inch difference in tread wear between front and rear. SWITCH one front wheel and one rear wheel. ROAD TEST again.
Internal components		OPERATE the vehicle in all transmission gears. If there is noise in the transmission in NEUTRAL, or in some gears and not in others, REMOVE and REPAIR the transmission. REFER to Automatic Transmission 6R80 . If there is noise in all gears, DISASSEMBLE the transfer case. REFER to Transfer Case . CHECK the planetary gears, the bearings, the upper and lower drive sprockets and drive chain for damage. INSTALL new parts as necessary.
Fluid level		FILL fluid to the correct level. REFER to Transfer Case .
The vehicle binds in turns/resists turning/pulsates/shudders in a straight line	Unmatched tire sizes Unequal amounts of tire wear Unequal tire inflation pressures Unmatched front and rear axle ratios	GO to Pinpoint Test K .
Transfer case whine - noise at all ranges	Incorrect fluid level or fluid quality Worn oil pump Under-inflated or oversized tires	CHECK that the transfer case is filled to the correct level. REFER to Transfer Case . DISASSEMBLE the transfer case. CHECK the oil pump for wear or damage. REPAIR as necessary. REFER to Transfer Case . CONFIRM the tires and wheels are correct for the vehicle. CHECK the tire inflation pressures are correct.
Transfer case growl/rumble - noise at all ranges	Damaged or worn bearings or planetary gear	DISASSEMBLE the transfer case. CHECK the bearings or planetary gear for wear or damage. REPAIR as necessary. REFER to Transfer Case .
Transfer case scraping/grating - noise at all ranges	Excessively stretched drive chain hitting the case	DISASSEMBLE the transfer case. CHECK the drive chain for wear or damage. REPAIR as necessary. REFER to Transfer Case .
Transfer case howl/hum - noise at all ranges or 4X4 only	Worn or damaged sun (input) gear, clutch pack (intermediate) gear or output shaft gear	DISASSEMBLE the transfer case. CHECK the gears for wear or damage. REPAIR as necessary. REFER to Transfer Case .