Alternator bearings or tensioner pulley?

[smileonimpact]

A strange noise started yesterday, I have narrowed it down to either the alternator bearings or auxillary belt tensioner pulley starting to fail. Its on a 110 tdi (ASV) and at first I thought it was a belt slipping but once you open the bonnet it's clearly something more serious.

Does anyone know if either of the likely candidates are prone to failure?, I have seen a couple of threads on here but nothing to point me one way or the other. I'm gonna take the tension off the aux belt soon as I get a chance and try and feel if either of these are shot.

Smile

[NicholasD]

Funnily enough, i just looked at this problem on my sisters beetle pd 1.9tdi.

If you leave it at idle, and switch certain things on, you will find a reasonant load at which the noise is loudest, after that it will go away (at more battery load, ie everything on) or after revs.

Turn everything electrical off and start to switch on some electrics, ie lights on, then try full beam, then creep the interior fan speed up, so that it JUST about begins to make the noise, and i bet if you (being very carefull, as in I do not in any way suggest you do this) stick something against the top of the tensioner (big square edge on the top which can be used to press against - I used one side of a rubber handles-set of pliers) the noise will die down. Told her to get a new spring tensioner as hers is so bad the battery light is being intermitant so must be letting the ribbed belt slip :S

Nick

[allytech]

Alternator pulley failure is etremely common

[smileonimpact]

You were spot on with your diagnosis allytech, many thanks.

I noticed an electrical burning smell this morning from the alternator area which prompted me to deal with the alternator issue quicker than I otherwise would have done.

I now have tourrettes syndrome, I swore at the haynes manual at least every 5 mins, the air was blue! simply remove the upper alternator bolt? how about remove the power steering pulley, follwed by remove power steering pump then remove auxillary belt tensioner! Kno***eads. So glad i tried to squeeze this job into my lunch break!

The one way drive system on the pulley was fooked it it was driving nothing, but when I got the old alternator off it did have early signs of over heating on the unused connector directly below the 2 pin connector. A quick phone call to eurocarparts and £119+vat got me a brand new alternator, which is now in place but thanks must go to haynes manuals for the misinformation on how to do the job!

Just need to re-assemble the power steering pulley, refit the p/s pump, aux belt tensioner, belt, air con pump......etc

thanks for your top advice, and speedy reply though, much appreciated.

smile (well nearly)

Edited 24 March, 2010 by smileonimpact