Symptom Chart - NVH

2009 Mercury Milan Premier, 3.0 1, AWDSECTION Symptom Chart - NVH
WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 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 & HARSHNESS . 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 AND HARSHNESS (NVH) for the next likely system and continue diagnosis.
SYMPTOM CHART - NVH

Condition Possible Sources Action
  • Drone type noise
  • Powertrain mount(s)
  • CARRY OUT the Powertrain/Drivetrain Mount Neutralizing  procedure in this article. TEST the system for normal operation after the repair.
  • 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
  • CARRY OUT the Powertrain/Drivetrain Mount Neutralizing  procedure in this article. TEST the system for normal operation after the repair.
  • Engine drumming noise - accompanied by vibration
  • Powertrain mount(s)
  • CARRY OUT the Powertrain/Drivetrain Mount Neutralizing  procedure in this article. TEST the system for normal operation after the repair.
  • Rattle - occurs at idle or at light acceleration from a stop
  • Powertrain mount(s)
  • CHECK the powertrain mounts for damage. INSTALL new mounts as necessary. For engine, Refer to the appropriate article in Engine for the procedure. For automatic transmission, Refer to the appropriate article in Transmission for the procedure. For manual transmission, REFER to DIAGNOSIS AND TESTING . TEST the system for normal operation after the repair.
  • Whine/moan type noise - pitch increases or changes with vehicle speed
  • Powertrain mount(s)
  • CHECK the powertrain mounts for damage. INSTALL new mounts as necessary. For engine, Refer to the appropriate article in Engine for the procedure. For automatic transmission, Refer to the appropriate article in Engine for the procedure. For manual transmission, REFER to DIAGNOSIS AND TESTING . TEST the system for normal operation after the repair.
  • Clunk - occurs when shifting from PARK or between REVERSE and DRIVE
  • Powertrain mounts
  • CHECK the powertrain/drivetrain mounts for damage. INSTALL new mounts as necessary. For engine, Refer to the appropriate article in Engine for the procedure. For automatic transmission, Refer to the appropriate article in Engine for the procedure. For manual transmission, REFER to DIAGNOSIS AND TESTING . TEST the system for normal operation after the repair.
  • Idle speed is too high
  • CHECK for the correct idle speed. TEST the system for normal operation after the repair.
  • 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 DIAGNOSIS AND TESTING .
  • 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 the appropriate article in Engine for the procedure. 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
  • Clunking noise
  • Coolant pump has excessive end play or imbalance
  • CHECK the coolant pump for excessive end play. INSPECT the coolant pump for imbalance with the drive belt off. INSTALL a new coolant pump as necessary. REFER to INSPECTION AND VERIFICATION or INSPECTION AND VERIFICATION for the Escape Hybrid. TEST the system for normal operation after the repair.
  • 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.
  • 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 INSPECTION AND VERIFICATION . TEST the system for normal operation after the repair.
  • Starter motor
  • CHECK the starter motor. INSTALL a new starter motor as necessary. REFER to REMOVAL AND INSTALLATION . 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 REMOVAL AND INSTALLATION . TEST the system for normal operation after the repair.
  • INSPECT the flywheel/flexplate for wear or damage. INSTALL a new flywheel/flexplate as necessary. Refer to the appropriate article in Engine for the procedure. 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
  • CHECK for obvious signs of damage or wobble during operation. INSTALL new as necessary. Refer to the appropriate article in Engine for the procedure. TEST the system for normal operation after the repair.
  • 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 the appropriate article in Engine for the procedure.
  • 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 the appropriate article in Engine for the procedure. 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.
  • Fuel injector
  • USE the EngineEAR to isolate the noisy injector(s). INSTALL a new injector(s) as necessary. Refer to the appropriate article in Engine for the procedure. TEST the system for normal operation after the repair.
  • Engine noise, upper end - ticking, knocking or rattle noise that occurs during idle or high idle during the first cold start of the day and may disappear as the engine warms
  • Valve train noise (bled down lifter/lash adjuster)
  • CARRY OUT the Valve Train Analysis Component Test in this article. INSTALL new parts as necessary. Refer to the appropriate article in Engine for the procedure. 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
  • REMOVE the spark plugs. INSPECT and INSTALL new as necessary. Refer to the appropriate article in Engine for the procedure. TEST the system for normal operation after the repair.
  • 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 the appropriate article in Engine for the procedure. 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 in this article. INSTALL new parts as necessary. Refer to the appropriate article in Engine for the procedure. TEST the system for normal operation after the repair.
  • Worn valve guides
  • CARRY OUT the Valve Guide Inner Diameter procedure in this article.
  • Excessive runout of the valve seats on the valve face
  • CARRY OUT the Valve Seat Inspection procedure in this article.
  • 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. REPAIR or INSTALL new spark plugs as necessary. TEST the system for normal operation after the repair.
  • Catalytic converter
  • Compare with a similar vehicle for what is acceptable noise.
  • Engine noise, lower end - ticking or knocking noise near the oil filter adapter
  • Oil pump
  • USE the EngineEAR to verify the oil pump as the source of the noise at low RPM. REPAIR as necessary. Refer to the appropriate article in Engine for the procedure. TEST the system for normal operation after the repair.
  • 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
  • CARRY OUT the Piston to Cylinder Bore Clearance procedure in this article.
  • 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
  • CARRY OUT the Piston Pin Bore Diameter and the Piston Pin Diameter procedures in this article.
  • 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
  • CARRY OUT the Connecting Rod Bearing Journal-to-Bearing Clearance procedure in this article.
  • 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
  • CARRY OUT the Crankshaft Main Bearing Journal-to-Bearing Clearance procedure in this article.
  • Engine noise, rear of engine - knocking noise at rear of engine
  • Damaged flywheel/flexplate
  • CARRY OUT the Flywheel Inspection or the Flexplate Inspection procedure in this article.
  • Engine vibration - vibration felt at all times
  • Excessive engine pulley runout
  • CARRY OUT the Engine Accessory Test. INSTALL a new engine pulley as necessary. REFER to IN-VEHICLE REPAIR for the 2.5L engine, IN-VEHICLE REPAIR for the 3.0L engine or IN-VEHICLE REPAIR for the Escape Hybrid. TEST the system for normal operation after the repair.
  • 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
  • Using the scan tool, CARRY OUT the cylinder power balance and the relative compression test. REPAIR as necessary. Refer to the appropriate article in Engine for the procedure. TEST the system for normal operation after the repair.
  • 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 flex plate by 120 degrees for a 3-bolt converter or 180 degrees for a 4-bolt converter. REFER to TORQUE CONVERTER DIAGNOSIS for the automatic transmission. TEST the system for normal operation after the repair.
  • Engine vibration - is felt with increases and decreases in engine RPM
  • Powertrain mount(s)
  • CHECK the powertrain mounts for damage. INSTALL new mounts as necessary. For engine, Refer to the appropriate article in Engine for the procedure. For automatic transmission, Refer to the GENERAL PROCEDURES for the procedure. For manual transmission, REFER to GENERAL PROCEDURES . TEST the system for normal operation after the repair.
  • 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
  • CARRY OUT the Neutral Engine Run-Up (NERU) Test. REFER to NEUTRAL ENGINE RUN-UP (NERU) TEST . ROTATE the torque converter, 120 degrees for 3-bolt or 180 degrees for 4-bolt. INSPECT the torque converter pilot outer diameter-to-crankshaft pilot inner diameter. REPAIR as necessary. REFER to TORQUE CONVERTER DIAGNOSIS . TEST the system for normal operation after the repair.
  • Engine vibration - mostly at coast/neutral coast. Condition improves with vehicle acceleration
  • Combustion instability
  • CHECK the ignition system. INSTALL new components as necessary. Refer to the appropriate article in Engine for the procedure. TEST the system for normal operation after the repair.
  • 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 the appropriate article in Engine for the procedure. TEST the system for normal operation after the repair.
  • Plugged fuel injector
  • REPAIR or INSTALL a new injector as necessary. Refer to the appropriate article in Engine for the procedure. TEST the system for normal operation after the repair.
  • Contaminated fuel
  • INSPECT the fuel for contamination. DRAIN the fuel system and refill. TEST the system for normal operation after the repair.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.