engine and drivetrain Alternator belt squeal at higher RPMs?

[jfunk]

Hello everyone,

 

So I've done a few searches here and I can't seem to find how people have solved this problem.  I have this annoying alternator belt squeal when the engine is under load and reaches about 4000 RPMS.  If I'm on the freeway and I bring it up to 4K it will squeal a little bit but then the squeal usually calms down.  It seems people have dealt with this problem on and off.  When I put on a new belt that works for about a month and then the problem starts again.  I'm now on my 3rd belt in the last 6 months.  I have the OEM alternator and I just replaced the bushings and that hasn't seemed to help.  The water pump was replaced about 10K miles ago so I'm pretty sure it's not that but I suppose it could be.  Does belt conditioner work?  I'm likely going to try that next since it's easy and only about $5.00.

 

When the car is idling and when I'm putting around below 4K there isn't any squeal.  Just when I get on the gas or rev it passed 4K.

 

Anything I'm missing?  Many thanks!

 

-Jesse 

Edited January 31, 2016 by jfunk

[sirius815]

The bushings you replaced - were those the internal ones?

[jfunk]

Nope!  They were the exterior alternator mount bushings.  Are there are bushing inside the alternator that need to be replaced? 

[TobyB]

No, there aren't any bushings inside the alternator- there are 2 bearings, however.

How are they?

 

One thing we're getting up to- if the pullies are getting really worn,

the V- belts don't work as well any more.  Especially the

smaller alternator one.  Is it still a V, or is it becoming U- shaped?

 

I am becoming more and more pear- shaped as I age...

t

[JohnM]

I had the same problem when I bought my 72 Tii. It turned out that it had a narrower v belt than the correct one.

[percy]

Even worse than what you describe would be a belt that squeals with the engine or vehicle not moving.

 

 

 

Several thoughts.

 

Rubbing a bar of soap (tallow) on the belt surface may alleviate some squeal on glazed surfaces.  But since you changed your belt, this is an unlikely scenario and the soap fix is a short lived fix.  Same with sanding to remove glaze, that generally occurs on older belts.  Having not purchased a belt recently, I am not aware of the newest offerings, but I am aware that belt design has changed so that some now have something that resembles cogs, grooves, kerf cuts and even tread for flexibility, reduced sound, longer life and efficiency.  One of those newer designs may be worth trying - if nothing else works.

 

Per Toby's comment, it may help if you take a yard stick and make positive your pulleys line up correctly with the driving crank pulley.  Even with new alternator bushings, that is no guarantee of the pulleys being in line with each other.  And - at speed, anything out-of-line may magnify the problem as the belt may not be able to flex enough at that higher velocity.  I would also carefully compare the dimensions of each pulley groove too.  That includes the crank drive pulley.  As Toby might tell you, it is rare that one belt shape will accommodate all pulley shapes, so if the pulleys are markedly different: squeal.

 

Does your belt say it is made for Goldilocks?  Could it be too tight or too loose and not "just right?"

 

Toby touched upon bearings or bushes in both the water pump and the alternator (and any other accessory driven by the same belt.).  If the bearings are beat - or close to beat, there may not be much you can do other than replace the bearings or de-tension the drive belt to abate the stress on those bearings.  It is unlikely, but new bearings could also result in too much drag on from that component and your belt may be screaming about it..  Removing the belt and turning each accessory  by hand may "hold" a clue.  Also, this should probably go at the very beginning of any belt checklist, over-tensioning is not the best practice.  Unless you have accessories that require an inordinate amount of energy to drive them, go with the absolute minimum.  Lastly, I occasionally drive a different 40+ y/o model that is equipped with power steering.  Belt squeal that was never a problem, but now occasionally the belt occasionally "chirps" when the steering wheel is turned aggressively.  The pump is obviously creating a huge load that exceeds the ability of the belt to drive it at matching crank speed.  The problem is not the belt, but rather the pump's resistance.  Either way it is a drag.

 

 

 

Edited January 31, 2016 by percy

[roadhog0]

For me, this problem started when I replaced my old belt. The first belt I got was the wrong size (length), the next fit properly length wise, but it still screamed just at a higher RPM. So I'm not sure if the auto parts store belts are the right ones. What I finally had to do was replace the factory alternator at about 90k miles and the squeal went away. So there's a good chance your bearings are crap in your alternator and once it gets up to 4000 rpm the bearings have too much resistance for the belt. Good luck!

[Mike Self]

There is a belt that is the proper length for a 2002 water pump/alternator but is too narrow.  That allows it to ride too deeply in the pulley sheaves; then it will overheat, stretch, squeal and eventually fail at a very young age.  

 

Check your owners manual and/or shop manual for the proper belt width--don't trust what the belt catalogs show.  They were incorrect 20 years ago, and there's no guarantee they've been corrected. 

 

cheers

mike

[DavidLMM]

Mike is right. Had the same problem, also at 4000 rpm. The belt that was on the car was "correct"; the replacement belt I got from the dealer was "correct"; both were wrong by a half-millimeter in width. Big deal? Big enough. Got a really correct belt from Blunt (pretty sure) and it's nice and quiet. I can rev without cringing now.

 

David

[jfunk]

I really appreciate all the thoughts and ideas here.  I've been getting my belts from the O'Reilly's down the street and come to think about it, the guys been selling me a universal belt that he says should work. I'll order the correct belt from Blunt and see if that solves it before going down the other paths.  I'll report back with updates.

 

Thanks!

 

-Jesse

Edited February 1, 2016 by jfunk

[Buckeye]

What I finally had to do was replace the factory alternator at about 90k miles and the squeal went away.

Hey, I will pay for shipping to send it to me if you did not throw out that original alternator and don't want it

[percy]

Mike is right. Had the same problem, also at 4000 rpm. The belt that was on the car was "correct"; the replacement belt I got from the dealer was "correct"; both were wrong by a half-millimeter in width. Big deal? Big enough. Got a really correct belt from Blunt (pretty sure) and it's nice and quiet. I can rev without cringing now.

 

David

 

Its hard to argue with Mike, the teachings of his father-in-law, the Air Force, or his neighborhood beavers.  An ill fitting belt certainly could result in noise, but with respect,  .5 millimeter width differential does not seem that critical of a factor unless you are using a belt that is no wider than a typical shoelace.  The point being that none of us can opine on incorrect width, depth or pitch of the belt that is currently suspected of high rpm noise making, unless its cross sectional dimensions are known, along with pulley sheave dimensions.  Fan belt dimensions can vary per manufacturer and application.  And used pulley sheaves are probably not dimensionally identical with new ones, meaning that most mass produced belts can conform to slight variations in size - and still perform adequately.

 

Since your post I have examined three sets of pulleys (waterpump, crank, alternator, and aircondition compressor) and associated drive belts.  One belt sits proud (taller and wider) than the pulleys.  The other two are recessed in some of the pulleys.  All of the belts are used and each is apparently of different manufacture, i.e., Gates, Goodyear and Dayton.  None of the belts exhibit the high rpm squeal that seems to be described in this thread.  So, while I agree that the wrong belt size/fit can result in noise, it does not negate the possibility that even the correct size will be any less quieter with misaligned pulleys or incorrect tension, or ailing accessory bearings.   And then there are belts that may be the correct size, but created with inferior materials that may cause substandard performance or premature failure.

[jimk]

V-belts of all configurations, even the multi-grooved belts rely on the friction between the sides of the belt and pulley.  If it rides on the bottom of the belt/groove, it won't pull much.  Have to set high like Percy says.  For multi-grooved belts, I have a gauge to measure the depth of the belt grooves for wear.

[Lee]

A simple dab of grease on the pulley will eliminate that oscillation caused by the friction between the pulley and the belt. If the squealing doesn't stop, then it comes from somewhere else. ;-)

 

PS - DO NOT apply the grease with the engine running. You may lose a finger or a hand right there... ;-)

[jimk]

Better to use belt dressing.  http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2055119.m570.l1313.TR0.TRC0.H0.Xv-belt+dressing.TRS0&_nkw=v-belt+dressing&_sacat=0

Ignore the sexy stuff!