Alternator/fan belt screech

Tiny
DR.PHILL1999
  • MEMBER
  • 1997 HONDA PASSPORT
  • V6
  • 4WD
  • AUTOMATIC
  • 200,000 MILES
My sisters car has been squealing since I bought it about three months ago. The other day I had to tow it home with a bad alternator. I replaced the alternator and while I was under there I found out the belt had shredded. I replaced the belt. Now the car's screech is loud. I thought, okay I have a maladjusted belt no problem right? Wrong I readjusted five times and no change I even went as far as to remove the belts on at a time it is the alternator belt. I replaced it with a slightly skinnier belt thinking it was too wide on the pulley. I am a fairly competent "shady tree" mechanic and I am puzzled. Also, I sprayed wd40 on it no change.
Monday, February 26th, 2018 AT 6:16 PM

10 Replies

Tiny
HARRY P
  • MECHANIC
  • 2,295 POSTS
Look for a pulley that is seizing up. Likely culprit would be the A/C pulley or the tension-er/adjuster pulley. Take the belt off and turn it by hand. If you feel any roughness or resistance in its rotation, then you have found the problem. Replace or bypass the pulley.
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Monday, February 26th, 2018 AT 7:42 PM
Tiny
DR.PHILL1999
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There are no seized pulleys. The car has three separate belts the one making noise is the alt fan belt I replaced the alt fan and belt and still squeals.
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Tuesday, February 27th, 2018 AT 12:01 AM
Tiny
HARRY P
  • MECHANIC
  • 2,295 POSTS
I did not say seized, I said seizing up. They can make a squeal and still be turning, but at some point soon they are going to stop completely. I can virtually guarantee that one of those pulleys is getting ready to quit completely -or- one of the other belts needs adjusting.

Also, sometimes, in order to get the belts tight enough, you have to use a pry bar or something along those lines on the adjustable pulley in order to get the belt tight enough to not squeal. Otherwise the belt will slip and squeal.

And just a FYI, WD40 has the nasty habit of causing belts to wear prematurely. It is really just not good for them. In the future, get some belt dressing at the parts shop.
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Tuesday, February 27th, 2018 AT 5:36 AM
Tiny
DR.PHILL1999
  • MEMBER
  • 12 POSTS
Okay thanks! I understand the liability of your situation I work at an auto store you have to be very careful because it could always be something. I will try to tighten the belt better but it is one of those formats where it has a tension bolt. So I could just be too scared to over tighten. Thanks for your help I will let you know what it ends up being.
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Tuesday, February 27th, 2018 AT 8:27 AM
Tiny
HARRY P
  • MECHANIC
  • 2,295 POSTS
Right if you look at the image I posted earlier, you can see that the alternator has an adjuster on it. In general, to get it tight enough, you have to put a pry bar on it and then tighten the bolt. Do not put your full weight into it, though. As you suggested that could be too tight. Realize that if you pry on it a little, and do not get it tight enough, you can always add a little tension by re-tighten it again. It is a good idea to have a helper pry while you tighten, or vice versa, if you can get a helper.
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Tuesday, February 27th, 2018 AT 10:26 AM
Tiny
DR.PHILL1999
  • MEMBER
  • 12 POSTS
Right now I am puzzled I replaced all the pulleys and still screeches. I had my buddy come and check belt tension, it is good. One guy said that some rubber from the old belt could be stuck in the crankshaft pulley. Could that be the issue?
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Monday, March 19th, 2018 AT 11:18 AM
Tiny
HARRY P
  • MECHANIC
  • 2,295 POSTS
It's either that or you're getting oil/grease/coolant on it as the truck runs. Try cleaning the pulleys (all of them) with a wire brush and maybe some engine degreaser. Then spray a little water on them (to get left over degreaser off) and then let it dry for an hour or two. Then put it back together and see how it goes.
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Monday, March 19th, 2018 AT 6:38 PM
Tiny
DR.PHILL1999
  • MEMBER
  • 12 POSTS
I fixed it today faulty "new" alternator" it is stupid that it was the one thing I thought was good. I mean I replaced it and it screeched. Yikes just goes to show why we test parts before we sell them. Thanks for your help I hope our conversation can help other people with similar problems.
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Monday, March 19th, 2018 AT 8:07 PM
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
This is a great example of never presuming that something is ok, as you have found new can be faulty, happy to hear that it is sorted, thank you for using 2car pros.
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Wednesday, March 21st, 2018 AT 6:01 AM
Tiny
HARRY P
  • MECHANIC
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Can't say I'm surprised. Most aftermarket parts are assembled by people who have almost no mechanical knowledge or skill. All they know is what their particular function. And no, that statement isn't meant to disparage them. It's just a fact of life. I can't remember how many times I've had that happen to me. Anyways, I'm glad to see you got it fixed. Please feel free to come back here any time.
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Wednesday, March 21st, 2018 AT 6:28 PM

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