Some 2008-2010 Ford F-Super Duty 250-550 trucks equipped with a 6.4L diesel engine may exhibit a random engine ticking/tapping noise that is most noticeable when engine coolant temperature is 185 degrees Fahrenheit or higher, and from base idle to about 1,500 rpm. Some customers may complain that this noise becomes more evident after 3,000 to 5,000 miles after an engine oil change.
The noise is most noticeable at the rear of the driver’s side front wheel well. 6.4L Powerstroke diesel engines exhibit this normal noise, caused by the relationship between engine block, crankshaft journals, bearing inserts and oil viscosity. “This relationship allows a pulsation that resonates through the cylinder block and is heard as a metallic ticking noise. This condition is present on all diesel engines,” according to Ford.
While current model diesels are substantially quieter, previous versions are just plain noisy, so advise the customer they’ll have to live with it.