Owners of some 2007-08 Ford and Lincoln models with 4.6-liter and 5.4-liter engines may complain of a high-pitched hoot or whistle from the accessory drive belt system at idle.
According to Ford, the noise is most obvious on cold start-up in temperatures below 40°F, usually stops after about 10 minutes of driving and is due to grooves forming in the nylon belt idler pulley.
Installing a new-design, more robust idler pulley, part No. 6L3Z-6C348-A, should eliminate the issue in short order.
Vehicles that are prone to the noise and can benefit from the updated idler pulley are 2007-08 F-150s and Mustangs with 4.6-liter and 5.4-liter engines; 2007-08 Lincoln Mark LTs/Navigators and Ford Expeditions with 5.4-liter engines; and 2007-08 Ford Explorer and Explorer Sport Trac and Mercury Mountaineers with 4.6-liter engines.
"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].