Serpentine belt tension questions

[Rob888]

The spec serpentine belt deflection for my 2010 two door Yaris hatchback is .43-.51 inches according to my 2010 Yaris Hatchback Factory Repair Manual. But the manual does not specify the amount of force to apply to the belt when measuring deflection.

The standard recommended belt deflection is 1/64" per inch of belt length. My serpentine belt is 10.5" between the centers of both pulleys. So the deflection should be 10.5x1/64=.16". But again, the amount of force applied to get 1/64" deflection per inch of belt length is never specified.

I have a belt tension measuring tool that measures deflection when 10 foot pounds of force is applied. How many inches of deflection would be in the specified range for my car with ten foot pounds of force applied?

Thanks for any replies.

[06YarisRS]

Not sure why they call it a "V" belt, but this came from my service manual. I'm not positive that this is what you're looking for.

https://i.imgur.com/gwLRbL9.png

[WeeYari]

A few years back Toyota issued a TSB addressing belt squeal. In it, the tension specs had been revised to reflect a higher degree of tension than previously specified. The TSB is on this site somewhere.

[WeeYari]

https://www.yarisworld.com/forums/showthread.php?t=54039&highlight=Tension+tsb

[Leegamer]

This is really the biggest issue with the yaris as far as I'm concerned. Fortunately it's pretty easy to tighten the belt once you've done it once.

[ern-diz]

When we pulled my alternator off to check if it was still producing the right amount of buzz, we tension'd the serpentine belt with 2 or 3 good ugga duggas :biggrin:

[kd5oldx]

my belt squeeked when i got my 2010 3dr.
i took off the alternator to find the tension arm takes the force for tension and alternator support and stabilizing. the 14mm bolt on the bottom of the alternator leaves the alternator loose when fully tightened. so it meant that the force goes entirely to the little arm. my arm had a nut tack welded on in the middle of the arm for some other use like a bypass pulley or something. upon deep inspection and removing the little arm the arm was cracked in the middle and the alternator was not stable. the arm would wiggle. the alternator would wiggle. the belt would squeak as sudden rpm changes occur. like everytime you go from AC off to AC on.

i welded the crack to make the arm solid again. all good. reinstalled

my advice on torque is everything you can possible muster with one arm. if or you are weak then both arms but you need a buddy to tighten bolt. get a gates belt. throw that thing on there. tighten it being careful of the VVT oil solonoid.

[andulong]

When I replaced the belt in my "08 Yaris I read all the specs on tightening and then went to work. I soon realized that there was barely enough room to get the belt on let alone get any kind of tools in there to take a measurement. I tightened it until it felt right to me. Couple days went by and it started squealing on startup. Tightened it just a bit more and all good.

[alanwagen]

It also seems like the Yaris is picky about which belts that won't squeal. It seems like we he've had good luck only with the OEM.