Belt whine with a twist

[Stephen03]

I changed my belts a few months ago, and re-inspected last night.

I always have had (since belt change) and still have belt whine when the engine is cold. But it goes away when warm, seems backwards to me.

I tried running the balance belt loose, and tight. No change.

Timing belt tensioned by twist and waterpump methods. Going to dig into next weekend and maybe loosen the timing belt a hair.


Any ideas why it only whines when cold?

Thanks,

Stephen.

[Slam]

Plastic tensioners/rollers, basically, putting up a fuss 'cause it's cold. My 83 didn't whine until I replaced the metal rollers with the new plastic ones. That's my $.02 anyway. If you're sure you've done your tensioning right there's probably no need to worry.

[John_AZ]

Is it a belt whine or a WP water pump bearing noise?
When you check your belts again, grab the WP pully and tug, pull, yank and feel for any out of normal movement.

Also, the balance belt tension roller is tensioned CW clockwise. This will put the BB balance belt below the WP pully.



GL
John

[Slam]

Another thought, looking at the diagram. Check the clearance between the balance belt idler and the belt. Should be .5mm. Credit card works. If too close to belt, will spin constantly.

[Stephen03]

It doesnt touch when the engines off, but when running it will spin. I stopped it with my finger while it was running but it didn't stop the whine.

[Aussie944S]

Stephen03,

got some balls putting your fingers in there, seen a bloke de glove 2 fingers doing something kinda the same with a truck.

sounds like the roller is too close

[Aufgeladen944]

It was the tensioner on mine; everything looked fine but the serpentine belt had gone a little bit loose. The tensioner seemed tight but it was actually broken.

Dunno, still weird.

[Porsche-O-Phile]

Try to find a set of the metal rollers if you can. I trust them more.

Have you retensioned?

A too-tight belt is far worse than a too-loose belt, but if it appears correct (other than the clearance between the idler and BB) I wouldn't mess with it too much. A little belt whine is nothing to lose sleep over. It's normal and I've run into it on a lot of 944s.

Out of curiosity what kind of belts are you using? Conti? Gates? Goodyear? Might possibly have something to do with it. I'm not aware of anyone doubt anyone seriously studying noise/whine differences by belt manufacturer (yet)...

[zrdeuce]

I am dealing with the same issue. For giggles I took the balance belt idler off and ran the engine for a couple of minutes. Guess what, no whine. I am now playing with getting the clearances on it just right, which doesn't seem easy. Having read the above posts, I think I will get is as close to spec clearances and just live with the whine.

[Stephen03]

Gates belts. Belive me I was careful when I stopped the idler.

We'll see next days off I guess.

[John_AZ]

The BB balance belt idler was discussed in depth this thread.

I get near "0" distance when I have the .5mm gap tool installed. No Noise.

Balance belt idler misinformation

John

[porschetub]

I've done all that, belt as new waterpump checks ok etc,still have the whine, what's the chance of the auto tensioner roller on mine being faulty as it's hard to check - the guys that work on these cars for a living will most likely have the stats.
I find the auto tensioner makes the belt tighter than the "twist test" tension.
By the way IMHO the BB idler is usually set to close,run the engine covers off and it should only counter the deflection of the belt when the revs come on.

[Stephen03]

Well I retensioned again after a 12 hour night shift, tightened the timing belt a bit and adjusted the balance belt idler roller up a hair to preload the balance belt. Still a little whine with belt cover off and hood open. But with covers on and hood down, I can hardly hear any whine and couldn't be happier.

Balance belt tensioner is rotated CW but it looks like the balance belt might hit the water pump pulley once in a while.

All seems well, I'll report back if anything changes.

[924RACR]

Maybe you're twisting it just a touch too hard?

That is, IMO, a practiced feel, for just how hard to twist...