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
Rattle, squeaks or buzz type noise - from the bottom of vehicle	Loose or damaged heat shield	INSPECT the exhaust system for loose or missing heat shields or foreign material trapped between the heat shields and the exhaust system components. If any heat shields are loose, INSTALL worm gear clamp 7L5Z-5A231-AA and tighten to 7 Nm (62 lb-in). If the heat shields are missing, INSTALL new heat shields or exhaust system components as necessary. If a rattle, noise or buzz condition persists, INSTALL a new heat shield or component as necessary.
Loose or damaged exhaust isolators		CHECK that the exhaust isolators are correctly installed. INSPECT the exhaust isolators for wear or damage. INSTALL new isolators as necessary.
Damaged exhaust isolator hanger bracket		INSPECT the exhaust system components for damage or broken hangers. INSTALL new components as necessary. CHECK for loose or damaged exhaust hanger brackets or fasteners. TIGHTEN bolts to specification or INSTALL new components as necessary.
Catalytic converter Muffler		MOVE the exhaust system to simulate the bouncing action of the vehicle, checking for exhaust-to-body contact while moving the exhaust system. Using a rubber mallet, lightly TAP on the exhaust components one at a time to duplicate the noise concern. DETERMINE if there are any loose or broken baffles or elements. REPAIR or INSTALL new components as necessary. TEST the system for normal operation after the repair.
Exhaust grounded to chassis		INSPECT for signs of exhaust components-to-body contact. If necessary, CARRY OUT the Exhaust System Alignment .
Drone or clunk type noise - from bottom of vehicle	Loose or damaged exhaust isolators	INSPECT exhaust isolators for wear or damage. INSTALL new isolators as necessary.
Exhaust grounded to chassis		INSPECT for signs of exhaust components-to-body contact. If necessary, CARRY OUT the Exhaust System Alignment .
Whistles, boom, hum or ticking type noise - noise tends to change as engine warms. Noises are often accompanied by exhaust fumes	Exhaust system leak	INSPECT the entire exhaust system for leaks. CHECK for punctures, loose or damaged clamps/fasteners, gaskets, sensors or broken welds. EXAMINE the chassis for grayish-white or black exhaust soot, which would indicate exhaust leakage at that point. To magnify a small leak, have an assistant hold a rag over the tail pipe outlet, while listening for a leak. REPAIR or INSTALL new components as necessary.
Catalytic converter Muffler		MOVE the exhaust system to simulate the bouncing action of the vehicle, checking for exhaust-to-body contact while moving the exhaust system. Using a rubber mallet, lightly TAP on the exhaust components one at a time to duplicate the noise concern. DETERMINE if there are any loose or broken baffles or element. REPAIR or INSTALL new components as necessary.
Exhaust muffler/resonator drain hole enlarged due to corrosion		NOTE: Check with vehicle on the ground, not on a hoist. CONFIRM drain holes are noise source. INSTALL new components as necessary.
Thermal expansion of exhaust versus heat shields		This is a normal condition.
Hissing or rushing noise - high frequency sound. Vehicle performance is unaffected	Exhaust system. Exhaust flow through pipes	MOVE the exhaust system to simulate the bouncing action of the vehicle, checking for exhaust-to-body contact while moving the exhaust system. Using a rubber mallet, lightly TAP on the exhaust components one at a time to duplicate the noise concern. DETERMINE if there are any loose or broken baffles or element. CHECK for missing or leaking Torca ® clamps. REPAIR or INSTALL new components as necessary.
Pinging noise - occurs when exhaust system is hot, engine turned off	Catalytic converter/exhaust system Thermal expansion of exhaust system	Cool down pinging is the exhaust system expanding and contracting during heating and cooling. This is a normal condition.
Vibration - occurs at idle and at low speeds. Also accompanied by clunk or buzz type noise	Loose or damaged exhaust isolators	INSPECT the exhaust isolators for wear or damage. INSTALL new isolators as necessary.
Loose or damaged exhaust isolator hanger brackets		INSPECT the exhaust isolator hanger brackets for wear or damage. INSTALL or REPAIR as necessary.
Damper broken or out of position if equipped		CHECK for the correct damper orientation in this article. RELOCATE to correct position and tighten nuts to specification. INSPECT for missing or damaged damper. INSTALL new components as necessary.
Exhaust system grounded to chassis		CARRY OUT the Exhaust System Alignment .
Engine drumming noise - normally accompanied by vibration	Damaged or misaligned exhaust system	INSPECT the exhaust system for loose or damaged fasteners, Torca ® clamps or isolators. CARRY OUT the Exhaust System Alignment .
Sputter type noise - noise worse when cold, lessens or disappears when the vehicle is at operating temperature	Damaged or worn exhaust system	INSPECT the exhaust system for leaks or damage. REPAIR as necessary.
Thumping noise - from the bottom of the vehicle, worse at acceleration	Misaglined exhaust system	CHECK the exhaust system-to-chassis clearance. CHECK the exhaust system isolators for damage. REPAIR as necessary.
Engine vibration - is felt with increases and decreases in engine rpm	Strain on exhaust system isolators	CARRY OUT the Exhaust System Alignment . REPAIR as necessary.
Drumming noise - occurs inside the vehicle during idle or high idle, hot or cold. Very low-frequency drumming is very rpm dependent	Exhaust system vibration excites the body resonances inducing interior noise	REPAIR or INSTALL new components as necessary.