fan belt squeal?

[dsy1]

All is fine until I get to about 2800 RPM on the highway, then I get a loud squeal that I assume is from a fan belt. I have tightened both belts (one for alternator and one for power steering) but it didn't solve the problem. (I know the expensive solution is to get an overdrive transmission so I don't need to run at 3000 RPM, but with 4.11 gears and a non-overdrive TH350 I have to work with what I have).

Next step is to remove one belt at a time to try to find out which one is making the noise. Both the water pump and alternator are new, so it should not be shaft/bearing problems. Any other ideas?

[72chevyk10]

tried belt dressing yet? thats worked for me before

[special-K]

Rev it up like that while you watch the belts and pulleys under the hood. I wonder since they are slipping at a steady high rpm,and not when you "snap" it,if there isn't an alignment problem causing the belt to not ride deep enough in the pulley. I have had a chronic belt slip when I revved the motor and using a deep groove Z/28 pulley on the alternator solved it. It was misaligned just a bit and I never could get it quite right. Never did figure it out.

[Stocker]

Unfortunately, belt dressing has not worked for me. If you can safely hold a bar of soap against each belt (one at a time so you can find the culprit), it will temporarily stop the squealing. Obviously keep your fingers, knuckles, clothing etc. out of belts & pulleys....

[dsy1]

The belts are the kind with the notches on the back side, maybe I'll try another brand if I can't solve it some other way. A little narrower wouldn't hurt, it would fit down in the groove a little better.

[leddzepp]

Originally Posted by dsy1

The belts are the kind with the notches on the back side, maybe I'll try another brand if I can't solve it some other way. A little narrower wouldn't hurt, it would fit down in the groove a little better.

Oops....sorry for editing your post above...I meant to hit the quote button

I agree, the deeper the belt sits in the pulley, the more "grab" it has, and the less likely to slip. In fact, I would be willing to bet that WILL solve your problem. It did in my case.

Belt dressing has NEVER worked for me, only made the problem worse. Carefully holding a bar of soap along the edge of the running belt as Stocker described above has worked many times for me...however it is only a temporary fix as stated.

[5150.4.67]

Make sure the belt isn't bottoming out on a severely worn pulley. This is evidenced by a shine on the bottom side of the belt......

[swamp rat]

Heres my delema, i have brand new pullies on the crank and water pump, a new alternator with new pully, i have test ran the engine without the pullys and get no squeal at all, i only get squeal with the alternator belt as i have tested with just one belt then the other. I have tryed both running a little too tight and a little loose.. I can see no visable sign's of missalignment.. I have tryed both Gates and Dayco belts to no avail.. My only other possible thought is that the 4X4 3/4T trucks supposably use a smaller diameter water pump pully from what i have read than the 1/2T to increase waterflow, so maybe the smaller pully creates more drag and is the source of the squeal? I plan to try a fan clutch some day to see if that helps.. yea its a pita for sure..

EDIT: Try using the search feature and type in belt squeal and you should find more threads on the subject.

[special-K]

It's usually at the alternator that they slip since that's the smallest pulley. You guys should try the Z/28 pulley. It helped me. They are designed for just this problem with hi-performance motors. They are deeper and solid. I don't a picture or I'd show you.

[1970 Bowtie]

dsy1,you said you replaced the water pump and alt.When you installed the belts were your hands free of grease(clean).Kind of an obvious question but just a thought.

[swamp rat]

Originally Posted by special-K

It's usually at the alternator that they slip since that's the smallest pulley. You guys should try the Z/28 pulley. It helped me. They are designed for just this problem with hi-performance motors. They are deeper and solid. I don't a picture or I'd show you.

Where would i find such a pulley?

[bajaracing]

i had a simular stubborn squeek with my power steering. No dressing would solve the problem. Ended up beign slight mis-alignment. Pulled the pump, added a spacer so it lined up perfectly. Problem has completely gone away.

[Shane]

if a belt squeals normally it's a good sign that it needs to be replaced ...