Rhythmic belt squeal

Earlier this year, when the weather was cooler, my B4 would have a rhythmic squeak when starting cold. Any kind of additional load on the belt (AC on, or lights on) would exacerbate it, but in any case it would go away after a minute tops. There was quite a bit of rapid wobble in the serp belt tensioner, regardless of temperature.

Fast forward to the jungle-like temperatures in the PNW lately, and now it no longer squeals at first start, but when starting after being already warmed-up, even a couple of hours later. The noise is similar (rhythmic and middle-pitched, not the steady high-pitched shriek of a typical belt), but louder. Load does not appear to affect it, and it lasts a bit longer than the cold squeal did before.

In both cases, when under way and driving there is no abnormal noise whatsoever. Engine sounds and feels healthy. Car has just under 160k, and the alternator is probably not original. I did timing belt about 2k and six months ago, with a new Litens tensioner and new INA roller.

I'm going to remove both the PS and serp belt tomorrow to be sure it's not the timing belt, but assuming that checks out and it is in fact the drive belts... what should I focus investigative efforts on, given the symptoms? The harmonic balancer? The idler tensioner? The whole idler assembly? The alternator pulley?

Prolly the balancer. I don't remember if they still make noise with the belts off. It's the rubber between the pulley and the hub the makes noise.

This is a classic issue with these motors.

Out of the two cars I have fixed it on it has been the crank pulley with the rubber dampener in it.

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The belt tensioner can a make a slight improvement but my bet is on the above.

I've had to do a couple harmonic balancers too. Symptoms were exactly as described - cold weather startup squeak, hot squeal.

The original ones have the serpentine belt driven by the outer part of the pulley which is mounted to the inner part via a rubber ring. When the rubber starts to go bad the outer part slips making a nasty belt squeal like sound. Since it is involved in the belt drive path it will react to alternator load.

The new ones changed the design - the outer serpentine belt drive ring is part of the center hub and the balance weights is rubber isolated in the middle. They won't ever fail in the same way as the older ones.

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I'll put marks on the balancer to confirm, but is there a chance of a false negative (marks stay put, noise happens, but it's still the balancer)?

What's the consensus on aftermarket vs. OEM?

Pretty much if it is bad the marks will move. It won't make noise otherwise.

I think aftermarket is the only option now. Last one I bought was made in Hungary I think, has been performing fine. Noticeable reduction in engine vibration when I swapped it too.

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Yup, marks slipped. Great, another poorly designed VW part kicks the bucket.

206danebmx said:

This guy is what you need: 028105243T

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as it happens this is the pulley i have, is it the most upgraded one? the latest to be produced?
its expensive tho from VW its more than $400, you can find cheap-o- aftermarkets for ~$130 maybe more. dont know if those cheap types are that good.

The originals ended in K (or was it Q?), and the newer ones in T. Febi ones go for ~95 shipped, Vaico for ~80, no-name crap for 37, and AAQ (made in Turkey) for ~70.

I replaced mine about seven years ago. Seems to me I paid about $75. No problems since then.

I'd weld the pulley to the hub before I'd give VW $400 for that.

I think I paid about $100 for the Febi that I installed. This was about 3 years ago.

I remember looking at the HB that came on my donor and it was VAG. PO was a VW tech and he got everything from the dealership. Not sure if he paid for everything...

-Todd

I got my latesy one at bora parts for $100, had it in for a year now with no issues.