Diagnosis And Testing: Engine: NVH: Overview

Inspection and Verification - NVH 

1. NVH symptoms should be identified using the diagnostic tools and techniques that are available. For a list of these techniques, tools, an explanation of their uses and a glossary of common terms, REFER to: Noise, Vibration and Harshness (NVH) . 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.
2. Verify the customer concern by operating the engine to duplicate the condition.
3. Inspect the engine for installation of an aftermarket oil filter. Review oil and filter maintenance history to make sure the vehicle has not gone beyond the standard Ford recommended oil change interval.
4. Check the engine oil level and check the oil for contamination. Low engine oil level or contaminated oil are a common cause of engine noise. If the oil is contaminated, the source of the contamination must be identified and repaired as necessary.
5. Visually inspect for obvious signs of mechanical damage.
6. If the inspection reveals obvious concerns that can be readily identified, repair as necessary.
7. NOTE: Make sure to use the latest scan tool software release.

   If the cause is not visually evident, connect the scan tool to the DLC.

8. NOTE: The VCM LED prove out confirms power and ground from the DLC are provided to the VCM.

   If the scan tool does not communicate with the VCM:

   • check the VCM connection to the vehicle.
   • check the scan tool connection to the VCM.
   • check for No Power To The Scan Tool, to diagnose no power to the scan tool, REFER to: Communications Network .

9. If the scan tool does not communicate with the vehicle:
   • verify the ignition key is in the ON position.
   • verify the scan tool operation with a known good vehicle.
   • to diagnose no response from the PCM, REFER to: Communications Network .

10. Carry out the network test.
    • If the scan tool responds with no communication for one or more modules, REFER to: Communications Network .
    • If the network test passes, retrieve and record continuous memory DTCs.

11. Clear the continuous DTCs and carry out the self-test diagnostics for the PCM.
12. If the DTCs retrieved are related to the concern, REFER to: Electronic Engine Controls .
13. If no DTCs related to the concern are retrieved, continue the inspection and verification if a noise concern is related to the engine. For vibration concerns and noise concerns such as powertrain mounts, air intake system and starter GO to Symptom Chart - NVH  .

    In some cases, a noise may be a normal characteristic of that engine type. In other cases the noise may require further investigation. Comparing the noise to a similar year/model vehicle equipped with the same engine will aid in determining if the noise is normal or abnormal.

    Once a customer concern has been identified as an abnormal engine noise, it is critical to determine the location of the specific noise. Use the EngineEAR/ChassisEAR or stethoscope (the noise will always be louder closer to the noise source) to isolate the location of the noise to one of the following areas.

    • Upper end of engine
    • Lower end of engine
    • Front of engine
    • Rear of engine

    Upper end engine noise 

    The fuel system, camshaft, timing drive components and valve train are common sources of upper end engine noise (ticking, knocking or rattle). Upper end engine noise can be determined using the EngineEAR/ChassisEAR or stethoscope on the valve cover bolts. If the noise is loudest from the valve cover bolts, then the noise is upper end. The EngineEAR/ChassisEAR or stethoscope can be used to further isolate the noise to the specific cylinder bank and cylinder. Removal of the valve covers will be required to pinpoint the source of the noise.

    Fuel system noise 

    A common source of engine ticking noise is the switching of the fuel pressure control valve to fuel volume control valve. After the vehicle is started the high-pressure fuel injection pump switches modes and it makes a louder noise than when the vehicle was first started. There is an inherent ticking noise that comes from the high-pressure fuel injection pump as it switches to the more fuel efficient mode using fuel volume control valve only. This noise may be characteristic of the fuel system switching from the fuel pressure control valve to the fuel volume control valve. This noise may be more noticeable as the normal diesel engine noise diminishes. This is normal engine noise that can be verified by listening to another vehicle. If the noise is excessive or irregular, use the EngineEAR/ChassisEAR or stethoscope to isolate the noise.

    Valve train 

    Hydraulic lash adjusters can make an engine ticking or tapping noise noticeable at any engine rpm or temperature and is audible through the wheel well or an open hood. However, with the hood down, hydraulic lash adjuster noise can be heard as a light tapping noise through the wheel well and is considered normal. The EngineEAR/ChassisEAR or stethoscope can be used to further isolate the noise to the specific cylinder bank and cylinder, some disassembly of the engine may be required to inspect for damage or wear.

    Turbocharger noise 

    Some vehicles may exhibit a turbocharger spool-down (hoot) noise on engine throttle tip-out when engine oil temperature is below 65 deg.C (150 deg.F) and/or an oscillating turbocharger whine at idle with engine oil temperature below 10 deg.C (50 deg.F). The 6.7L diesel includes design improvements to reduce overall inherent diesel engine noise. These sound reduction improvements enable certain characteristic noises to be more easily heard. Using the incorrect engine oil can negatively impact the level of noise. REFER to: Engine - Overview .

    Lower end engine noise 

    The crankshaft, connecting rod(s) and bearings are common sources of lower end engine noise (tick/tap or typewriter noise). This noise should be considered characteristic as it is not detrimental to engine durability. The 6.7L diesel includes design improvements to reduce overall inherent diesel engine noise. These sound reductions improvements enable certain characteristic noises to be more easily heard. Lower end noises can be determined by using the oil pan or cylinder block lug bosses. If the noise is loudest from these areas then the noise is lower end. If an engine noise is isolated to the lower end, some disassembly of the engine may be required to inspect for damage or wear. Using the incorrect engine oil can negatively impact the level of noise. REFER to: Engine - Overview .

    Front of engine noise 

    A common source of noise from the front of the engine (squeal, chirp, whine or hoot) is the FEAD components. To isolate FEAD noise, carry out the Engine Accessory Test, REFER to: Noise, Vibration and Harshness (NVH) .

    Oil pump noise 

    The oil pump may whine due to air getting into the lubrication system near the oil pump. One source of an oil pump whine are cut gaskets between the upper oil pan and the engine front cover (the 2 gaskets that seal the oil pump). Another cause is oil aeration which could be a missing O-ring seal on the oil pick-up tube or a cracked oil pick-up tube. Removal of the upper oil pan may be necessary to inspect internal engine components.

    Some other noises from the front of the engine (ticking, tapping or rattle) may be internal to the engine. Use the EngineEAR/ChassisEAR or stethoscope on the engine front cover to determine if the noise is internal to the engine. Removal of the engine front cover may be necessary to inspect internal engine components.

    Rear of engine noise 

    A common source of noise from the rear of the engine (knocking) is the flexplate. Inspection of the flexplate will be necessary.

14. After the noise is localized, note the characteristics of the noise, including type of noise, frequency and conditions when the noise occurs and GO to Symptom Chart - NVH  .