Screaming Valeo Alternator or belt tension pulley bearings?

[billkirk]

The E36 M43 engine with serpentine belt has been emitting a high pitched whine for several weeks. I suspect the Valeo alternator is the problem, though the two reversing/tensioning pulleys aren't ruled out. I've tried squirting WD40 around without any change, which is why I'm inclined to believe it's something internal to the alternator where I haven't squirted the WD40.

I can't find an exploded diagram of the Valeo alternator in the BMW TIS or EPC to give me an idea of where to shoot a little oil to try to stifle the noise to isolate the source. I don't want to just randomly squirt WD40 into the alternator, though it probably wouldn't hurt.

Does anyone have any experience tracking a similar problem, and /or a URL for a Valeo component diagram? Nothing turns up for me when I search for Valeo alternator, or variations thereof.

Thanks for any help...

Bill K. in Sydney
1996 E36 316i Compact M43 5-speed
1989 E34 525i M20 Auto

[winfred]

the alt bearings usually make a deeper noise and don't really squeel, you can remove the belt and spin it by hand and hear/feel it rumble, it's harder to do that with the rollers as sometimes they need to be under a load to make noise but when they really get bad you can hear them, they are usually the sorce of a squeel