squealing alternator belt

Kerry Lange

PCS Member
I've been having problems with a squealing alternator belt off and on for the past year. It began last spring when I replaced all of the belts on the car. So much for preventative maintenence. At the same time, I replaced the alternator with a new one that I'd had laying around for a few years.
The squeal initially occured only on startup when cold, but has now graduated to pretty much any time I start the car and lasts for ten to fifteen seconds. It is definitelly the alternator belt, as it doesn't occur when I remove the belt.
I've done everything I can think of including putting the original alternator back on, sanding the pulleys, replacing the belt twice with both cheap, non ribbed belts, expensive ribbed ones, and finally, the original one. I've tightened the belt as much as possible, but cannot solve the problem. All pulleys are in alignment. I had considered replacing the fan clutch, but am hesitant to drop another $70 for nothing, as it appears to be functioning as it should.
Please don't suggest belt dressing, as I've learned from past experience that it makes a mess of the engine and hood insulation and is only a temporary fix.
 
Loosen the belt. If it is too tight, it will squeal. Sometimes reversing the direction that the belt turns will solve the problem. To reverse the direction of the belt, you take the belt off, turn the belt 180 degrees, and reinstall..
 
I had the same problem now and then with the Lifeliner. As you stated, belt dressing fixes it but only for a short while. My problem was cured when I replaced the belt with a thicker belt. I thought I had the right belt but turns out the Advance Auto replacement was actually just a little bit too narrow.

No issues so far.
 
Pulleys can just wear to the point that they need to be replaced. Also be sure the belt is not riding so low in the groove of the pulley that it is on the bottom. I had a Chevrolet once, that would not keep the battery charged; finally an experienced mechanic showed me the pulley on the alternator; he changed it and no more problems. It was not noisy, though, as I remember from about 30 years ago.
 
Well, Thanks for all the advice, but so far, no solution. I did however, make a couple of interesting observations. First off, the diameter of the pulley on my "new" alternator was 1/4" larger. Secondly, I noticed that after running for less than thirty seconds, the pulley was too hot to touch, even though it isn't noisy and spins freely.
I put the original alternator back on, tried on all three belts, tightened the belt to various tensions, but it is still noisy on startup.
Another observation that may or may not be relevent, is that while the belt is squealing, the engine's rpms are lower, but they immediately increase when the belt stops squealing. Since the alternator is the only item being run by that pulley, I don't know what else could be causing it to drag.
 
I'm going to put this out. you start your car it puts a drain on the battery. the regulator opens up the alternator puts a increased drag on the shaft by working harder to bring the battery back up. if the load is so great that your engine is pulling down how about checking that battery. a high amp battery may start the car with a dead cell. do a hydrometer check on it and see why its pulling so much of a load. the pulley is heating up because the belt is slipping on it. if both alternators do the same thing it's time to stop looking at them for the cause of the problem. it's some were else in the system is causing the heavy load on them. or as stated you have the wrong wigth belt. look up the right belt don't just drop in with the old one a get one like it. but you not describing a aulternator problem.
 
John, I replaced the battery this past August with an 875 CCA one, so I'm going to assume for now that it's good. In the meantime, I wasted more money on a Gates belt, cleaned the pulleys with thinner and still had the problem. At least I now have a lifetime supply of alternator belts in my trunk.

With that being said, since I had my brother over helping me yesterday, he stood at the front of the car and listened after I started it. He felt that the noise was coming from the engine pulleys as opposed to the alternator. We then snugged up the p.s. and air pump belt. This morning all I got was a one second chirp instead of a fifteen second squeal when I started the car, so I suspect we're on the right track. I've yet to snug up the A/C belt, so I'm hoping that will be the end of it. None of these belts were what I considered loose, but they sure are tight now!
 
Check the FSM for the specifications of how tight the belts should be. You might find that there is a bearing going bad on one of the accessories on the engine. If you tighten the belts too much, you run the risk of damaging the front bearings because of the tension pulling against the bearing. Usually a belt should have at least 1/2" to 3/4" of deflection across the two pulleys, as measured in the middle. I would loosen all the belts and then spin each accessory to make sure that there is no binding as they turn. Squeals equal friction, and friction equals heat.
 
it is vary possible that the drive pulley off the crank is worn enough to cause the belts to slip on it. tighten the accessory like Paul has suggested and if it squeals have some one watch the lower pulley to see if it's slipping there or on the accessory. then only pull the one that's slipping tighter. if it still squeals you have to determine which pulley is worn and change that one. but not only do you have belts but a spare alternator. always good to have. then you know what part you don't need. that's the one you have extra of.
 
Power steering belts

I glanced through most responses and didn't see the one I've been seeing more often with these big old heavy cars as they get older - the PS pump fades. Mine is failing and I hear it as I turn right sometimes. The bearings are slowly failing, Stressing the belt and making it slip - and it seems as thought the right turn is hardest at first. Try turning right at various speeds and actually, turn all the power accessories on, the radio, a/c, defrost, lights, high beams etc, and if it only squeals under turns, it maybe the PS pump. Just a thought.
 
Well guys, first time in a long time that I've had no belt squeal or chirp on startup this morning.
Paul, the belt deflection is around 1/2 inch on all four belts, so I think I'm safe there.
Harry, I did have a squawk from the power steering belt if I turned as far as the wheel would go in either direction. That problem has now been solved by tightening the p.s. belt a bit more. I had never gotten around to re tightening the new belt after replacing it last spring, as it is a bit of a pain to get to. I assume that a new belt does stretch some after the initial installation.
For the time being, I'm just going to sit back and enjoy a nice quiet starting car. However, it doesn't take me long to get bored, so I will take the advice provided and go back and check each individual pulley sometime in the near future providing something else doesn't crop up first.
Thanks to everyone for their advice. It's made me aware that there's more to look at than just a simple solution.
 
If it doesn't squeal, then leave it alone!!!!!! Why look for trouble where there isn't any. :myopinion:
 
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