Alternator Pulley Question

[nate_o]

So I have the all too common AC / Alt belt squealing and breakage. I have tried a number of belts and "solutions" with out much success. I have noticed that when the belt is squealing bad and then I stop the engine and check the 3 pulleys involved the alt pulley is the only one thats warm. Makes me think thats where my problem is coming from, mabe the pulley is too worn? Mine is the 2 piece design pulley. I thought I remember reading a post about the 2 piece pulleys being a problem but I cant find that post now.
What do you guys think?

[TylerDurden]

As you may know, I tried a non-standard setup about 5 yrs ago... a total fail.

Since then, I've been using a stock AC config with pretty good results. I logged 26K miles over the past year (YTD) with one belt and tensioned only two or three times.

My current opinion is that a smooth idle is the best way to ensure belt life. But, my alternator was new 5 years ago so maybe the 2-piece pulley wear is not an issue for me.

I did recently need to replace my regulator... the brush holder cracked and I was getting intermittent charging. So that could be something to examine.

I'm also hearing a lot of rattle in the alternator at the terminal end, so I'm thinking the bearing retainer ("tolerance ring") has failed. This has happened before (can't remember which vehicle), and may be more common on these diesels than other engines.

I don't know if the pulley is the root of the issue, but I do know that the belt behaves differently at different engine speeds, so some harmonic effects are involved... So, I'd also ensure the alternator is working/spinning properly and the engine is humming smoothly.

[surfcam]

I use to own the same car. The most I could get out of those pulleys was about 80,000km and very pricey with no after market parts. The problem pulley has a large diameter bearing with a very narrow race. Their should be another pulley behind it that is fix to the shaft. The problem pulley is an idler.

[nate_o]

I have been looking for a new pulley without much luck. Anyone know what the part # is?
Tyler- The idle thing make sense. The belts flap like crazy at idle. Might try turning up the idle some to smooth it out.
I have replaced the alternator, tried the back bend idler, tried several different belts and sizes ( currently using a gates 10x670 ) and still blowing belts.

[TylerDurden]

Surfcam refers to the wacky WP pulley that some later cars had, where one of the two sheaves could spin independently and act as an idler. They are expensive, so I swapped in a non idle version on one of my rigs. AutohausAZ has them for $75.

The pulley on the alternator might not have a VW part number, but an auto-electric shop should have something that works. Bling shops could have some fancy billet pulleys for $$$$.

[Fatmobile]

There is a nice cheap AC delete that works well.

[nate_o]

Fatmobile- I may have to do that as a last resort but im trying to keep ac if possible.

surfcam - yes I have that same idler pulley but it seems to be fine. spins nice and smooth.

took the alt pulley off and there are grooves worn in them. Not much luck finding replacement vw pulley. May just have to source a pulley from motor shop like Tyler suggested. Question - How do you measure a pulley? Is it outside diameter or diameter of where belt rides?
Also I know there are different profiles or angles on pulleys, anyone know what profile are pulleys are?
Thanks