How tight should belts be?

[iwishiwas-all*]

I put brand new alternator belt on, and tightened it, but because my last one shot off (old old belt) after i tightened it, I did not tension this one as much.

So I would like to know, what is the "norm" amount of tensioning any serpentine belt should have?

Is there a way to tell? I turn the belt inbetween the pullys, when i put it on i could go 90 degrees, but now I can get a little more. How do you know how tight is tight? I do not wish to damage my alternator or my waterpump, but at startup, the belt sqeals and the voltmeter on my car reads in the 12's while when it stops sqweaking it reads 13.5-8 ish.

Speaking of which what is the proper voltage I SHOULD be seeing on my voltmeter?

thanks

[FRoSt415]

First question, just tighten till they is little slack or play with the belt. then after a few weeks tcheck and tighten again because belts wear in and after a week or so become loose since it is in use so come back and tighten it. Second, the voltage reading for teh alternator should be 13.8 to 15.3 volts with no lights or accessories on.

[iwishiwas-all*]

uh oh, so the culprit for the low voltage?

hmmmmmmmmm

[KoukiMonsta]

well while its slipping u get less voltage, which makes sense. tighten it up and see if you get improvenment. it may be time for a new belt.

[burnsauto]

the general rule i use for belt tension..

At the middle of the belt, you shouldn't be be able to turn it over 180º, twisting the belt with your fingers you should be able to turn it around 90º (a little past that is fine).

I'm not a big fan of that "half inch of play" because that changes with every belt when the distance changes. This way it stays more consistent.

[ManoNegra]

the general rule i use for belt tension..

At the middle of the belt, you shouldn't be be able to turn it over 180º, twisting the belt with your fingers you should be able to turn it around 90º (a little past that is fine).

I'm not a big fan of that "half inch of play" because that changes with every belt when the distance changes. This way it stays more consistent.

Generally what my friends and I do when installing belts.

[s14unimog]

the general rule i use for belt tension..

At the middle of the belt, you shouldn't be be able to turn it over 180º, twisting the belt with your fingers you should be able to turn it around 90º (a little past that is fine).

I'm not a big fan of that "half inch of play" because that changes with every belt when the distance changes. This way it stays more consistent.


I'll agree with this comment. I think that is a good, and fairly accurate way, to measure the tension. Another thought would be the less the better. The looser you can run the belts, the longer the shaft bearings will last. On top of that, the looser a belt is the lower the HP consumption will be; because the side load on the bearings will be minimal.

[Bigsyke]

How do you know the belt isnt slipping at high loads? You have to have 7mm-9mm of play at all times, having a loose belt causes heat and friction.

7-9mm of free play at 20lbs in the center if the belt I believe. Plus not always will the belt squeal.