Owners of 1999-2006 Ford F-Super Duty pickups or 2000-05 Excursion SUVs with diesel engines may complain that the engine's vacuum pump runs continuously, or not at all. In the case of the latter, the climate control system may also default to the Defrost mode, while the 4WD system may become inoperative.
Ford reports all these symptoms are limited to trucks built prior to June 27, 2005, and most likely are due to a defective vacuum pump.
Installing a redesigned pump, part No. 6C3Z-2A451-BA, should eliminate further troubles. Before installing the new pump, check and, if necessary, repair any leaking or pinched vacuum lines.
"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].