Replacng the Coupling on a Viscous fan

[staceyb]

Erm help!

Trying to replace the coupling on a viscous fan on an R reg Audi A4 Avant and can't get it off. Haynes recommends using a certain sized spanner to remove the bolt but it doesn't seem to want to budge and I really don't want to have to put the car back together to find a way of doing it at a later date.

Mucho thanks

[lukeb]

I recently had the viscous unit off my V reg to change the cambelt, but it doesn't quite sound like your situation. Mine (1.9 TDI) involved a peg spanner to hold the belt pulley from the front, and a 3/8 drive 8mm hex bit on an extension plus breaker bar to loosen the long bolt that held it to the block from the back. Perhaps you could describe what you're trying to do in more detail? And what engine is it?

[staceyb]

Its the same car and engine as yours. I'm trying to replace the oil filled coupling that turns the viscous fan (the fan itself is perfectly fine). The only thing I haven't tried is using a peg spanner. Where did you get yours from?

[agent006]

It's not a reverse thread is it?

[staceyb]

agent006 said:

It's not a reverse thread is it?

95% don't think so, tried it quite forcefully both ways.

[lukeb]

It's a normal right handed thread - as opposed to the accessory belt tensioner bolt that is left handed. You'll definitely need a beefy peg spanner as that sucker is well tight. I started off trying to bodge it with an angle grinder key (3mm steel) which was working until it bent. What finally got it was when I welded two little nuggets of steel bar to the end of a 2' section of 5mm angle iron. If you don't have the resources to go down that route there is (unsurprisingly) and Audi Special Tool to do the job, or perhaps somebody sells a fit 'em all adjustable peg spanner? Clearance between the viscous unit and the pulley that drives it is tight - approx 10mm perhaps, so such a tool would need to be slimline.