Pinpoint Test F: Engine Noise

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. 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) .

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 aids in determining if the noise is normal or abnormal.

Once a concern is 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 is always louder closer to the noise source) to isolate the location of the noise to one of the following areas.

• Fuel injector(s)
• Upper end of engine
• Lower end of engine
• Front of engine
• Rear of engine

Fuel injector noise 

A common source of an engine ticking noise can be related to the fuel injection pump or fuel injector(s). This is normal engine noise that can be verified by listening to another like vehicle. If the injector noise is excessive or irregular, use the EngineEAR/ChassisEAR or stethoscope to isolate the noise to a specific fuel injector.

Upper End Engine Noise 

A common source of upper end engine noise (ticking, knocking or rattle) includes the camshaft(s) and valve train. 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, the noise is within the 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 is required to pinpoint the source of the noise.

Lower End Engine Noise 

A common source of lower end engine noise (ticking or knocking) includes the crankshaft, connecting rod(s) and bearings. Lower end noises can be determined by using the engine oil pan or lower cylinder block. If the noise is loudest from these areas, the noise is within the 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.

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) .

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 flywheel/flexplate. Inspection of the flywheel/flexplate is necessary.

Some engines have timing drive components at the rear of the engine and may be the source of noise (ticking, knocking or rattle). Use the EngineEAR/ChassisEAR or stethoscope on the rear of the engine if the noise is suspected to be internal to the engine. Some disassembly of the engine may be required to inspect for damage or wear.

Turbocharger Noise 

A common source of noise is the turbocharger. Some whine or air rush noise is an acceptable condition.

To help locate the source of engine noise, REFER to: Engine Noise Identification and Location .

Possible Sources 

• Expanding/contracting materials
• Thin or diluted engine oil
• Low engine oil level
• Vacuum leak
• Cooling system concern
• Powertrain mount(s)
• Drivetrain
• Accessory drive system concern
• Air intake system concern
• Turbocharger bypass valve
• Turbocharger
• Engine or transmission interference to chassis or body
• Starter motor
• Fuel injector
• Fuel pump
• Fuel injection pump (direct injection engines only)
• Flywheel/flexplate
• Timing drive system concern
• Valve train component concern
• Cylinder head
• Balance shaft assembly
• Engine oil pump
• Lower end rotating assembly (connecting rods or crankshaft) concern
• Pistons/cylinder walls

• Compare the noise concern to a like vehicle, similarly equipped.

Is the noise of concern present in the like vehicle? 

• Ignition OFF.

• Visually inspect the powertrain components and all possible causes listed for obvious signs of mechanical damage.

Is any mechanical damage present? 

• Check the engine oil level.

Is the engine oil level OK? 

• Check the engine oil for contamination.

Is the engine oil free of contamination? 

• Check the vehicle service history and make sure the correct engine oil used is documented.

Is the correct engine oil used based on the vehicle service history? 

• Ignition ON.

• Carry out the PCMKOEO and KOER self-tests.

Are any Diagnostic Trouble Codes (DTCs) present? 

• Check the engine for an overheating condition.

Is an engine overheat condition present? 

• Check the coolant pump for excessive end play. Inspect the coolant pump for imbalance with the drive belt off.

Is any concern with the coolant pump present? 

• Inspect the vacuum hoses for leaks and check the engine for a vacuum leak.

Is a vacuum leak present?