Some 2007 Yaris models may emit a squealing sound from the engine bay. One likely cause of the noise, according to Toyota, is the serpentine drive belt slipping on the various pulleys.
Replacing the drive belt with an improved design belt, part No. 90916-02500, and tightening the belt using revised specs should eliminate the squeal.
Start the fix by installing the new belt. Next, start the engine, let it run for about 20 minutes to stretch out the belt, then shut the engine down.
Using the illustration above, place a belt tension gauge in the span shown and tighten the belt until the tension reads 102-123 ft.-lbs.
If you don't have a tension gauge, just measure the deflection of the belt in the span area shown in the illustration. When properly tightened, the belt should deflect .410 to .450 inch.
"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].