Belt Tightness?

[PCGUY112887]

How tight exactly should a serpentine belt on a motor be? Specifically my 3500. I have been trying to get rid of some belt noise lately, I thought it was coming from my power steering pump pulley but now I think it may be my tensioner. I did think maybe the belt was causing it, so I replaced it and that's when I remembered how tight my belt is. The tensioner is off the 3500, and I am using a 3100 belt (69.5"). The 3500 tensioner seemed the same. I don't know how tight the belt is on a stock motor, but when I put mine on I have to push the tensioner up all the way and then it is a fight to get it slid over the alternator pulley... it is TIGHT and I never really thought about it before, the tensioner is basically forced in the tightest position it can have.

Is the pulley system spaced out a bit differently on the 3500 making me need a longer belt or should it be this tight? I am wondering if the noise is coming from the tensioner pulley and I wonder if it is being caused be being SO tight. It hasn't made any noise up until a week ago, just started it and noticed it, it's been this tight for over a year now.

[gsEnterpries]

I'd think that may be just too tight, remember sometimes tight is good, just not in this situation.I would probly go with a slightly longer belt possibly a 70.5"or 71". There are usually notches on the tensioner body then an arrow on the piece that moves back and forth. The arrow should sit in between two notches, which ones, where they are that i don't know but in my many years as a mechanic thats how you can also tell how much slack is in the belt and if the tensioner needs to be replaced. I hope this helps.

[IsaacHayes]

If you have the same style tensioner, and the accessories in the same spots, then that should be a non-issue.

It's possible the idler pulley on the tensioner is going out. If you loosen the belt from off the PS pump, can you wiggle the pulley (cracked?) mine was cracked once and sounded like a super charger... LOL $15 new pulley fixed that.

[ForcedFirebird]

If you have the same style tensioner, and the accessories in the same spots, then that should be a non-issue.

It's possible the idler pulley on the tensioner is going out. If you loosen the belt from off the PS pump, can you wiggle the pulley (cracked?) mine was cracked once and sounded like a super charger... LOL $15 new pulley fixed that.

Could it be the accy pulley diameters were changed on a few items in the 3500? I would think buying a belt for the 3500 on a 3500 engine would be the way to go.

PCguy, that belt is way too tight, even just from the installation description. Every motor I have ever changed a belt on was easy to slip the belt over when the tensioner was in the full open position.

[IsaacHayes]

Using the tensioner tool, mine is how he describes. You roll it over the alt....

If he is using all of his 3100 accessories on the 3500, then nothing should be different.

[PCGUY112887]

I am using all 3100 accessories aside from the tensioner, which appeared the same. I could not use the 3500 belt setup since it was designed for having no PS pump and had an idler pulley in a different position. I put on my 3100 idler pulley to the correct position on the 3500 timing cover.

What I wonder is, since the AC compressor didn't quite bolt up correctly, maybe the mounting area for it is pushed out slightly on the 3500 block making my belt too tight?

[PCGUY112887]

Well it turns out that it is just my tensioner pulley that is making the noise. I thought I had the 3500 one on there, but after more research I forgot that I couldn't use that one since it has a ribbed pulley and I am using a smooth pulley like on the 3100, so my tensioner is really old and worn! My mechanic says my belt tightness is normal, so I am not worried about it anymore. Just ordering the Goodyear tensioner since it has a metal pulley vs the Autozone one which has plastic.

[IsaacHayes]

I was going to say, I doubt it was your belt. 3500 tensioner probably routes the belt to the ribbed side like you said, and was probably in a different spot factory than your 3100.