Serpentine Belt Replacement - Is it possible to get it too tight?

[keith204]

I'm about to replace the serpentine belt on my 2007 Yaris. From reading around on here, I see that if it squeals, it's too loose. However, would a belt that's too tight put bad pressure on the pulleys?

Since nobody seems to be mentioning a too-tight belt, I'm thinking that it's probably difficult to get it too tight.

Thoughts?

[CrankyOldMan]

Yes. Over-tightening the belt can/will cause premature failure of one or more bearings, usually the water pump or alternator. Welcome to the World!

[bail_w]

The rule of thumb with serpentine belts is to try to twist the belt 90 degrees in the middle of the longest span - it should twist 90 degrees but no more.

[bronsin]

Yes thats what Ive heard the 90 degree twist thing.

Which makes no sense to me because no matter how tight the belt is you can twist it 90 degrees!

I guess what I would do is tighten it so it squeeks. Then a little more. More. More. Until it stops. Then back it off a hair.

What could it hurt if it squeeks? :iono:

[tmontague]

I tighten it so that it is very firm when pushed down in the middle of the longest span. I allow it to move a cm or so either way w/ quite a bit of force pushing on it.

[eseibel67]

You can make it good and tight without damaging bearings. When it spins, the belt is looser than when it's standing still.