Alternator/Serpentine Belt Squealing 2007 Yaris 1NZ-FE Engine

[nighthawk421]

I have a 2007 Yaris 3dr. liftback 184,000 miles with the 1.5L INZ-FE engine. Whenever I leave AC on when turning off car, the serpentine belt makes a loud squealing sound for a few moments immediately after starting car again. When I turn off AC before shutting off engine, it generally does not make the squealing sound when engine is started up again.

I asked the local Toyota dealership once, and they said that this was typical of this Toyota model.

Questions:

a. Does anyone else have this issue with the Yaris 1NZ-FE engine?
b. Is there a known reason for this?
c. Is there anything that can be done other than turning off all loads (lights, AC, etc...) prior to starting engine?
d. Is this a sign of upcoming alternator/serpentine belt/belt tension pully failure?

Thanks for your help and input.

[WeeYari]

Typical? Yes. Your dealer didn't lie. Search 'belt squeal' and sit back as the dozens of search results load up.

The Yaris does not have an automatic belt tensioner as found in most other vehicles. Therefore it requires periodic manual tension adjustments. It may also, given vehicle age and mileage, simply be in need of a belt replacement.

[nighthawk421]

Thanks for the feedback. I'm assuming manual belt tension adjustment is pretty easy, like loosening alternator mount and pulling it tighter before re-tightening bolt?

I'll also check the actual belt, but think it was replaced recently. Perhaps the dealer that replaced belt didn't tighten it correctly??

[BLH]

Just be careful where you apply tension to tighten the belt.

Some folks have damaged the camshaft timing oil control valve. By using a bar to help in holding the alternator tight enough while tightening up the bolts.

There is even a note in the service manual to avoid damaging the valve while setting the belt tension.

It is possible the dealer tightened it on the low side of the specification and is stretched a bit as it ran in.

[Leegamer]

I usually have to adjust mine around this time of year when the temperature changes. I noticed yesterday I had a bit of a squeal in the morning.