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Symptom Chart - NVH: Notes

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 & HARSHNESS Article. Since it is possible that any one of multiple systems may be the cause of the 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 & HARSHNESS Article for the next likely system and continue diagnosis.
SYMPTOM CHART - NVH

Condition Possible Sources Action
  • Drone type noise
  • Powertrain mount(s)
  • Drumming noise - occurs inside the vehicle during idle or high idle, hot or cold. Very low-frequency drumming is very rpm dependent
  • Engine vibration excites the body resonances inducing interior noise
  • Engine drumming noise - accompanied by vibration
  • Powertrain mount(s)
  • Rattle - occurs at idle or at light acceleration from a stop
  • Powertrain mount(s)
  • Whine/moan type noise - pitch increases or changes with vehicle speed
  • Powertrain mount(s)
  • Clunk - occurs when shifting from PARK or between REVERSE and DRIVE
  • Powertrain mount(s)
  • Idle speed is too high
  • CHECK for the correct idle speed.
  • Accessory drive bearing hoot - occurs at idle or high idle in cold temperatures of approximately 4°C (40°F) or colder at the first start of the day
  • Accessory drive idler or tensioner pulley bearing is experiencing stick/slip between ball bearings and the bearing race
  • CARRY OUT the engine cold soak procedure. REFER to NOISE, VIBRATION & HARSHNESS Article.
  • PLACE the EngineEAR probe directly on the idler/tensioner center post or bolt to verify which bearing is making the noise. INSTALL new parts as necessary. REFER to ACCESSORY DRIVE BELT Article. TEST the system for normal operation after the repair.
  • Accessory drive belt noise, squeal or chirping
  • Defective/worn or incorrect accessory drive belt
  • Misaligned pulley(s)
  • Pulley runout
  • Damaged or worn accessory drive
  • component or idler
  • Fluid contamination of the accessory drive belt or pulleys
  • Damaged or worn accessory drive belt tensioner
  • Damaged pulley grooves
  • Whine/hum - occurs when unlocking the vehicle or opening the door with the engine off (Gasoline Turbocharged Direct Injection (GTDI) only)
  • Fuel pump module
  • Acceptable condition. Fuel pump module turns on before engine start to prime the fuel system.
  • Whine or moaning noise
  • Air intake system
  • CHECK the air cleaner and ducts for correct fit. INSPECT the air intake system for leaks or damage. REPAIR as necessary. TEST the system for normal operation after the repair.
  • Whistling noise - normally accompanied with poor idle condition
  • Air intake system
  • CHECK the air intake ducts, air cleaner, throttle body and vacuum hoses for leaks and correct fit. REPAIR or ADJUST as necessary. TEST the system for normal operation after the repair.
  • Turbocharger intake tube assembly leaking
  • REPAIR or INSTALL a new tube as necessary. TEST the system for normal operation after the repair.
  • Loose connections or damage to air intake hoses and tubes
  • TIGHTEN hose clamps. INSPECT for damage and REPAIR as necessary. TEST the system for normal operation after the repair.
  • Air leaks at turbine housing, blown joints or damage exhaust
  • INSPECT for leaks. Leaks can usually be detected audibly or visually, by a discoloration caused by escaping hot exhaust gases. REPAIR as necessary. TEST the system for normal operation after the repair.
  • Carbon build up in the turbine housing
  • Turbocharger imbalance due to foreign object/damage
  • REPAIR as necessary. TEST the system for normal operation after the repair.
  • Turbine bearing failure
  • Inoperative turbocharger bypass valve
  • Whine or air rush type noise
  • Turbocharger
  • Acceptable condition. Some whine or air rush noise is common.
  • Chirp or whoosh sound
  • Turbocharger bypass valve
  • CHECK the turbocharger bypass valve. REPAIR as necessary. TEST the system for normal operation after the repair.
  • Hissing noise - occurs during idle or high idle that is apparent with the hood open
  • Vacuum leak
  • USE the Ultrasonic Leak Detector/EngineEAR to locate the source. SCAN the air intake system from the inlet to each cylinder intake port. DISCARD the leaking parts, and INSTALL a new component. TEST the system for normal operation after the repair.
  • Vehicles with a plastic intake manifold
  • Acceptable condition. Some plastic manifolds exhibit this noise, which is the effect of the plastic manifold.
  • Grinding noise - occurs during engine cranking
  • Incorrect starter motor mounting
  • INSPECT the starter motor for correct mounting. REPAIR as necessary. REFER to STARTING SYSTEM Article. TEST the system for normal operation after the repair.
  • Starter motor
  • CHECK the starter motor. INSTALL a new starter motor as necessary. REFER to STARTING SYSTEM . TEST the system for normal operation after the repair.
  • Incorrect starter motor drive engagement
  • INSPECT the starter motor drive for wear or damage. INSTALL a new starter motor as necessary. REFER to STARTING SYSTEM Article. TEST the system for normal operation after the repair.
  • INSPECT the flexplate for wear or damage. INSTALL a new flexplate as necessary. REFER to ENGINE MECHANICAL - 3.5L Article or ENGINE MECHANICAL - 3.5L GTDI Article. TEST the system for normal operation after the repair.
  • Engine noise, front of engine - knocking noise from lower front of engine
  • Damaged or separated crankshaft pulley/damper
  • Engine noise, front of engine - ticking, tapping or rattling noise from the front of the engine
  • Timing drive components
  • REMOVE the accessory drive belt. REFER to ACCESSORY DRIVE BELT Article.
  • USE the EngineEAR to isolate the noise to the engine front cover.
  • REMOVE the engine front cover and INSPECT the timing drive components. INSTALL new parts as necessary. REFER to ENGINE MECHANICAL - 3.5L Article or ENGINE MECHANICAL - 3.5L GTDI Article. TEST the system for normal operation after the repair.
  • Engine noise, upper end - ticking noise near the fuel rail and intake manifold
  • Fuel rail clip
  • CHECK for loose or damaged fuel rail clip(s). REPAIR as necessary. TEST the system for normal operation after the repair.
  • Fuel injector
  • Fuel injection pump (GTDI)
  • This is normal engine noise that can be verified by listening to another vehicle. If noise is excessive, REPAIR as necessary. TEST the system for normal operation after the repair.
  • Engine noise, upper end - occurs mostly with a warm engine at light/medium acceleration
  • Worn or damaged spark plugs
  • Carbon accumulation in combustion chamber
  • Bore scope the cylinder. ELIMINATE carbon buildup. TEST the system for normal operation after the repair.
  • Engine noise, upper end - rattling noise from the valve train. Worse when the engine is cold
  • Low oil level
  • CHECK the oil level. FILL as necessary.
  • Thin or diluted oil
  • INSPECT the oil for contamination. If the oil is contaminated, CHECK for the source. REPAIR as necessary. CHANGE the oil and filter. TEST the system for normal operation after the repair.
  • Low oil pressure
  • CARRY OUT an oil pressure test. If not within specifications, REMOVE the engine oil pan. REFER to ENGINE MECHANICAL - 3.5L Article or ENGINE MECHANICAL - 3.5L GTDI Article. INSPECT for a blocked oil pick up tube. TEST the system for normal operation after the repair.
  • Worn valve train components
  • CARRY OUT the Valve Train Analysis  Component Test . INSTALL new parts as necessary. TEST the system for normal operation after the repair.
  • Worn valve guides
  • Excessive runout of the valve seats on the valve face
  • Engine noise, upper end - pinging noise
  • Gasoline octane too low
  • VERIFY with customer the type of gasoline used. CORRECT as necessary. TEST the system for normal operation after the repair.
  • Knock Sensor (KS) operation
  • Incorrect spark timing
  • CHECK the spark timing. REPAIR as necessary. TEST the system for normal operation after the repair.
  • High operating temperature
  • INSPECT the cooling system for leaks. CHECK the coolant level. REFILL as necessary. CHECK the coolant for the correct mix ratio. DRAIN and REFILL as needed. VERIFY the engine operating temperature is within specifications. REPAIR as necessary. TEST the system for normal operation after the repair.
  • Spark plug
  • CHECK the spark plugs. INSTALL new spark plugs as necessary. TEST the system for normal operation after the repair.
  • Catalytic converter
  • Acceptable noise.
  • Engine noise, lower end - ticking or knocking noise near the oil filter adapter
  • Oil pump
  • Engine noise, lower end - light knocking noise, also described as piston slap. Noise is most noticeable when the engine is cold with light to medium acceleration. The noise disappears as the engine warms
  • Excessive clearance between the piston and the cylinder wall
  • Engine noise, lower end - light double knock or sharp rap sound. Occurs mostly with a warm engine at idle or low speeds in drive. Increases in relation to engine load. Associated with a poor lubrication history
  • Excessive clearance between the piston and the piston pin
  • Engine noise, lower end - light knocking noise. The noise is most noticeable when the engine is warm. The noise tends to decrease when the vehicle is coasting or in NEUTRAL
  • Excessive clearance between the connecting rod bearings and the crankshaft
  • Engine noise, lower end - deep knocking noise. The noise is most noticeable when the engine is warm, at lower rpm and under a light load and then at float
  • Worn or damaged crankshaft main bearings
  • Engine noise, rear of engine - knocking noise at rear of engine
  • Damaged flywheel/flexplate
  • Engine vibration - vibration felt at all times
  • Excessive engine pulley runout
  • Damaged or worn accessory component
  • CARRY OUT the Engine Accessory Test. REPAIR or INSTALL a new component as necessary. TEST the system for normal operation after the repair.
  • Engine vibration - at idle, a low-frequency vibration (5-20 Hz) or mild shake that is felt through the seat/floorpan
  • Cylinder misfire
  • Engine or torque converter out of balance
  • VERIFY the torque converter-to-crankshaft pilot clearance is correct. REPAIR as necessary. RE-INDEX the torque converter on the flexplate by 120 degrees for a 3-bolt converter or 180 degrees for a 4-bolt converter. REFER to AUTOMATIC TRANSMISSION - AUTOMATIC TRANSAXLE/TRANSMISSION - 6F50/6F55 Article for the transaxle. TEST the system for normal operation after the repair.
  • Engine vibration - is felt with increases and decreases in engine rpm
  • Powertrain mount(s)
  • Engine or transmission grounded to chassis
  • INSPECT the powertrain/drivetrain for correct clearances. REPAIR as necessary. TEST the system for normal operation after the repair.
  • Engine vibration - increases intensity as the engine rpm is increased
  • Engine out-of-balance
  • Engine vibration - mostly at coast/neutral coast. Condition improves with vehicle acceleration
  • Combustion instability
  • Engine vibration or shudder - occurs with light to medium acceleration above 56 km/h (35 mph)
  • Worn or damaged spark plugs
  • INSPECT the spark plugs for cracks, high resistance or broken insulators. INSTALL a new spark plug(s) as necessary. REFER to ENGINE IGNITION SYSTEM - 3.5L/3.5L GTDI Article. TEST the system for normal operation after the repair.
  • Plugged fuel injector
  • Contaminated fuel
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