My fiero has been squealing forever it seems. I have run out of ideas.

I have a 4.9L with 105 amp GM alternator (smaller than stock caddy alt.) one dayco pulley attached to the waterpump hole, the stock water pump, and the stock harmonic balancer.

Heres the facts:

When I remove the belt and start it up, it does not squeal.

It only seems to squeal when you give it throttle. not at idle.

Sometimes it will be squealing while in gear and driving and all the sudden it will stop. when I resume at the next light, it starts again.

If I drop into neutral while driving, it will normally stop. until I go back in gear. Sometimes it will squeal again, sometimes it wont.

Heres what I have done.

replaced junk yard alt. with another junk yard alt.

replaced junk yard alt. with a new rebuilt alt.

replaced dayco pulley.

replaced belt, with gatorback belt. expensive one.

tried belt dressing (makes it worse.)

tightened the belt to every possible tension.

shimmed the alternator both ways to see if the alignment was off with the other pulleys.

Could it be the water pump? the engine has about 145K on it. it pumps just fine.

The only other thing I can think of is the alignment of the pulleys. It looks straight.

Heres some pics

[This message has been edited by collinwestphal (edited 09-20-2004).]

yes it could be the water pump. I've had a waterpump do that over time they start to gain resistance to turning and will eventually squeel But the water pump that did that to me didn't have nearly as much belt touching it as yours does. So I suggest pulling the belt off and hand turning the water pump to see if it resists any. Should be easy to turn and require force to turn at all. Try that then look at your alignment. The best way to check is look for rub marks on the sides of the belt. If there is an issue it will rub one side bad.

Stu

That does not look like much belt wrap on the alternator pulley. Could you not use the rear idler to help get more belt in contact with the alternator? Try disconnecting the electrical connector from the alternator and see if it still squeaks. If it does, then there are other problems, if not, then your alternator load is too much for the belt.

thanks for the suggestions, I will try the alt. connector tomorow. Why would the alt. be too much load for the belt?

Does anyone else have their belt routed like mine?

100+ amps is a lot of load and if you do not have more than 1/2 of the pulley covered by the belt, then it might be slipping- may not be, but that is where I'd start looking. Here is a pic from my van and you can see how much more of the pulley is covered:

YES!! I finally found out it is the belt slipping on the alternator pulley. I did not realize that the pulley had so much more resistance when it is plugged in. The difference is night and day. I'm going to try the slightly larger stock caddy alternator pulley. Otherwise, I may look for a bigger one than that or add another idler pulley to add more surface area.

As Cooter mentioned, your problem isn't the size of the pulley but the geometry of the belt going over it is wrong. You need to get more belt wrap on that pulley to really solve the problem.

Here's a picture of the wrap on our alternator on our 4.9 in the Finale.

John Stricker

quote Originally posted by collinwestphal: where can I get a bigger pulley? Mine is 2 3/8" diameter. My stock caddy unit has a 2 5/8" diameter. I could swap that one on. Or, I could just get a longer belt, and add another pulley to the right of the alternator pulley which will force more of the belt on the alternator pulley. anyone know of a small pulley that would do the trick? for the flat side of the belt. I may have to make a trip to the junkyard.

[This message has been edited by jstricker (edited 09-21-2004).]

I went to the JY today and got a pulley off a 3800 N/A engine and installed it just below and to the left of the alt. pulley. This definately helped. It still squeals, but only after med-heavy acceleration. I'm still looking into another easy fix for this.