How do I adjust idler pulley on Balance Shaft

Tidybuoy · 07-31-2015, 10:05 AM

I just replaced the belts and I think I've got everything done correctly however, I am confused on the directions for setting the idler Pulley on the balance shaft.

The Directions from the Porsche Shop Manual:

10. After adjusting drive belt tension, adjust idler pulley. Use special tool 9207 or 0.5mm feeler gauge so there is a clearance of 0.5 mm between drive belt and pulley when upper portion of drive belt is preloaded 0 to 1 mm (see sketch). Tighten idler pulley in this position. If correct gap cannot be reached. turn idler pulley 180 degrees and repeat adjustment. Tighten mounting nut to specified torque.

I don't understand the "0 to 1mm preload" comment. Can anyone put this in layman's terms?

Thanks in advance...

kevingross · 07-31-2015, 12:54 PM

I just adjust the gap with the belt properly tensioned. No idea on the preload.

Tidybuoy · 07-31-2015, 02:54 PM

When I adjusted the Idler Pulley, I was having a hard time measuring the .5 gap. Question: If there is a gap (any gap) I would think that the Idler Pulley will not spin when the engine is started because the belt is not touching the pulley - is that correct? However, when the engine is warm, maybe the pulley will start moving?

Currently, when my engine is cold, the Idler Pulley is moving so I'm thinking that I have the gap set incorrectly. Does this sound correct?

Thanks!

thomasryan · 07-31-2015, 07:22 PM

Watch Van's video. Credit card between the idler and the lower balance shaft and the long run of the belt should be a hair away from the idler.

If the balance eccentric is adjusted for proper tension and these conditions cannot be met, the eccentric needs to be moved up to where the proper tension is reached again in its arc. It will actually have the proper tension in two places.

I had a difficult time also.

Tidybuoy · 08-03-2015, 04:08 PM

Quote:

Originally Posted by thomasryan

Watch Van's video. Credit card between the idler and the lower balance shaft and the long run of the belt should be a hair away from the idler.

That was a great tip - especially since I was measuring the .5mm on the top of the roller and not between the bottom and the sprocket.

Thanks - it's purring like a kitten now.