Ford reports that some 2005-09 Mustangs may produce a whining sound from the rear axle while being driven on the freeway. One likely cause for the noise, says the manufacturer, is harmonics from the rear differential traveling through and into the rear axle housing. Installing a pair of tuned dampers from a special kit, part No. 5R3Z-3C246-A, onto the axle housing near each wheel should eliminate the whining sound.
The illustration above shows a tuned damper already installed on the driver's-side of the axle assembly. Note the “UP” arrow and LH marking. These provide the correct orientation for installation—the dampers are not interchangeable. Be aware that all Mustangs built after Nov. 15, 2004, already have threaded holes on both sides of the axle assembly to accept the dampers, so drilling isn't required on most vehicles. If the dampers are already installed and the whining sound is still there, says Ford, continue troubleshooting until the source of the noise is found.
Some 2002-03 Cooper and Cooper S models may turn on the oil pressure warning light even though the crankcase is filled to the proper level. If a check with a manual gauge shows that the oil pressure is okay, go to the starter motor because there's a good chance its heat shield has chafed through the engine harness, creating a short in the pressure switch circuit. Repairing or replacing the harness and installing a new-design heat shield, part No. 12411495806, should eliminate further trouble.
Owners of 2004 Touareg SUVs may complain of a whining sound from the rear locking differential when making turns. Volkswagen says the noise is most prevalent on trucks with VIN breakpoints between 7L-4D000039 and 7L-4D059806, and is due to excess friction between the differential clutch plates. Draining the rear differential and filling it up with a newly formulated final drive oil, part No. G052196A2, should help eliminate the condition.
"Factory Fixes" is written by Jim DePalma, a 30-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via e-mail at [email protected].