Mk V GT Tdi 140 ancillary belt tensioner

[andyr]

Hi people, am looking at buying a Golf as in the subject line, I'm aware of turbo problems, head porosity etc, but-
Should the engine ancillary drive belt tensioner 'vibrate' up and down whilst running?? I seem to remember my 150 Bora have the same thing and being told the tensioner needed replacing??
Just that we've seen one or two with this happening.
Cheers

[andyr]

So... Having now seen tensioners either fairly stationary or bouncing erratically I've done a bit more hunting and found that the problem is down to the alternator pulley becoming seized! The pulley is a clutched affair and spins freely one way but locks the other.
The problem.....
http://www.youtube.com/watch?v=mbsmoEP3eT4&feature=youtu.be
The fix.....
http://www.youtube.com/watch?v=fyosuYbPxr4

Thought I'd share as no-one seemed to know the answer.