squealing AAN serpentine belt

[hermanio]

Hello,

i have a problem that driving me crazy . my serpentine belt of my UrS4 is squealing, i recently changed my PS pump, alternator, visco, serpentine belt and belt tensioner pulley/bearing. and it is still squealing... the sound seems to come from the belt tensioner. is it possible that the belt tensioner is worn out ?

[s2_bo]

If you changed the bearing it shouldnt be making any noise..

Maybe its the bearing on the cambelt tensioner.. They can make a racket when they ware out too...

[hermanio]

i recently changed my timing belt with tensioner and water pump.., the serpentine belt tensioner seem to vibrate a little bit if the trottle is inceased, is that normal ?

[UrS4boy]

my serpentine belt of my UrS4 is squealing, i recently changed my PS pump, alternator, visco, serpentine belt and belt tensioner pulley/bearing. and it is still squealing... the sound seems to come from the belt tensioner. is it possible that the belt tensioner is worn out ?

Go back out to the car. Take the tension off the serp belt tensioner (and lock it there). Start the car. If you still have a squealing noise, it likely is the cam belt tensioner or the water pump. If you have no noise, somehow it is the serp belt tensioner (or the belt rubbing on the cam belt cover).

Here is a link to a serp belt tensioner DIY: http://forums.quattroworld.com/s4s6/msgs/22579.phtml

[hermanio]

Thanks for the advice, when i take the tension of the serp belt i have no noise. what could it be ?

[UrS4boy]

Thanks for the advice, when i take the tension of the serp belt i have no noise. what could it be ?

Look at the things that are driven by the serpentine belt: the tensioner pulley, the power steering pump, the alternator, the viscous fan and the air conditioning compressor. You need to spin each of these (with the belt tension off) to determine which one is the problem. The only one that you haven't mentioned already is the viscous fan pulley (and bearing) so it merits more investigation. Here is a post that will help you with that:

http://forums.quattroworld.com/s4s6/msgs/33332.phtml

[hermanio]

Thanks, the visco clutch and bearings are allready changed. when i spin the pulleys there are no strange noises. the sound seems to come from the tensioner, i hope you now understand this problem is driving me crazy the sound is the same as in the first seconds of this movie

http://www.youtube.com/watch?v=sli3FnPfdQ4

[HMS-S6]

Thanks, the visco clutch and bearings are allready changed. when i spin the pulleys there are no strange noises. the sound seems to come from the tensioner, i hope you now understand this problem is driving me crazy the sound is the same as in the first seconds of this movie

http://www.youtube.com/watch?v=sli3FnPfdQ4

Have you thought that the spring in the tensioner has gone weak? I left mine locked untensioned all last winter and ever since then it has been a little noisey in the morning.

[hermanio]

so you think i need to change the tensioner because of the spring worn out ?,i think the sound comes from the belt slipping at the tensioner. is it normal that the tensioner vibrates a little bit when i rev the car?

[UrS4boy]

so you think i need to change the tensioner because of the spring worn out ?,i think the sound comes from the belt slipping at the tensioner. is it normal that the tensioner vibrates a little bit when i rev the car?

Did you check to see if the three allen head bolts are properly tightened, holding the tensioner firmly to the engine block? I say this because the tensioner should not move if you rev the engine. Otherwise, the Torx bolt holding the tensioner pulley (with its replaced bearing) might be loose or the bearing is not correct or the two halvers of the pulley were not properly re-riveted or bolted back together. If none of those are the solution, then you need a new tensioner. I had one that had a cracked case (which prevented the spring from providing the proper tension on the belt).

Good luck.

[hermanio]

just back from the car, ive taken the tensioner of and checked it. when i turn the pulley there are no sounds (the bearing is 500km old). the tensioner is locked good with the 3 bolts. the spring is still strong enough i think because i need to use some force to get the tension off. when i apply more tension on the belt the sound gets worse. a other thing i found was that i heard sometimes a small squeal when i turned the pulley on the alternator. but when i start the car the sounds dont seem to come from the alternator. the sounds seems worse when the engine is cold

[UrS4boy]

Stupid question: The belt is the correct length (1693 mm) (item 1, below) and is new, right?

[V6quattro]

What brand of the belt do you use?

[hermanio]

Brand is contitech, its the correct length. could a belt begin to squeak when its sprayed with WD-40 ?

[UrS4boy]

Brand is contitech, its the correct length. could a belt begin to squeak when its sprayed with WD-40 ?

Well, WD40 *is* a form of lubricant and belts *do* squeal when they slip. As a result, you *might* have a belt that has slippery bits in various sections, causing slippage followed by stoppage (momentarily) which *could* be the cause of the squeak. You might have to replace the belt with a brand new one to see if the belt with the WD40 on it is the problem. ALternately, you might be able to get away with spraying a belt dressing on the belt (to make it a bit less slippery).