Mark944na86

What are you using for timing and balance belt tension measurements?

MXM

I think the idler pulley is in the "furthest" position away from the balance belt. I adjusted it for 0.5mm distance from the belt below it, and in that position it naturally touches the belt passing by above.

90-degree method. But since this is my first ever timing belt job, I don't really know how easily one should be able to turn the belt. And I couldn't check it on the old belt, because it was way too loose.

MXM

Released some tension on the balance belt - squealing still there.

Then I noticed some marks on the outer half of the timing belt:



Removed the distributor cover, and it appears that the timing belt tries to slide off the camshaft sprocket, with only the water pump roller holding it in.



Is this due to excessive tension? Or too little tension?

krystar

make sure u have the correct tensioner roller.

it's very easy to swap the timing belt tensioner and the balance belt tensioner. one faces inwards, other faces outwards

Jay W

I had a similar problem with my 968, although the tensioner for the timing belt is a completely different design. In my case the tensioner pulley was cocked slightly to one side and that ran the belt back too far on the cam pulley. I straightened out the tensioner pulley and it rides in the correct place on the cam pulley. Check to make sure your tensioner stud is not bent.

Also what is that black spot on the new water pump pulley? Is that burned belt?

MXM

It's rubber from the belt indeed, but I don't believe it's burned. The car ran for 5 minutes at most, the belt was just a little warm, and so was the pulley.

Mark944na86

I would suggest not running the engine again until you have checked for correct tension on both the timing and balance belts with a tool -- at least a Krikit if nothing else.

I would also consider replacing your rollers to ensure they are all good, and are the correct ones.

Otherwise, I get the feeling this car is going to to have bent valves in very short order. This is really not an operation you want to feel your way through with trial and error.

MXM

Right, bumping this thread up one more time.

Finally had the time to do some more work. I basically removed everything and reinstalled. There was some rubber on the waterpump pulley and the idler, so I cleaned both. The backside of the belt had also few spots of hardened (melted?) rubber, cleaned it too. I hope it wont keep doing that...

I've set way less tension on both belts this time. I can turn the balance belt almost 180 degrees with some force now.

The timing belt also has less tension now, and I can just turn it 90 degrees at the longest span. I can't set it any looser, or it starts skipping teeth on the cam sprocket. Strangely, it looks like the distance between teet is longer on the cam sprocket than on the belt. The belt sits just fine on the crankshaft sprocket and on the tensioner, but it really requires some effort to get it onto the camshaft. Even after I manage to stretch it over, and tension the belt a little bit, as I start turning the crank slowly, it does this:



Can this be just a bad belt? Anyway, this is how it sounds now:

http://www.youtube.com/watch?v=k0Qv9Ro9mT8

Major improvement over the last attempt, I reckon most of it is down to the balance belt tension, though. Timing belt still moves back and forth all the time, but stays more or less in the middle, didn't move to the outside in few minutes or so. Gonna experiment some more this evening. If it starts leaving rubber marks again, I'm gonna consider getting a new belt.

944Ross

I've never heard of a belt shrinking, only stretching. That's really weird if it is under tension; how much? Is that turning the engine backward?

Mike C.

"The backside of the belt had also few spots of hardened (melted?) rubber, cleaned it too. I hope it wont keep doing that..."

Um... you may want to replace that belt. A lot less expensive than bent valves...

MXM

It hasn't shrunk, it was like that from the start. I'm turning the engine forwards (clockwise). Which is when the left side starts to separate, unless I tension the belt a lot more. I don't have a gauge still, so this is purely subjective.

But should the new belt be such a struggle to get on the camshaft sprocket? I expected it to just slide in...

ernie9468

Can I give you a piece of advice -STOP- & get someboby who can do the job properly your playing with fire, +1 to you Mark 944 his gone end up with bends valves in a jiffy if he keep going at it this way.

Jay W

I have read others on this list say that one brand of belt just does not fit properly onto the cam sprocket. They then buy another brand and it works just fine. I do not remember which brand is the bad one. Buy a new belt due to the damage on that one and get a different brand while you are at it.

Usually I have a bit of difficulty getting the belt all the way around the cam sprocket but once it is on there it never tries to pull back off like it is not seated in the grooves of the pulley.

MXM

I don't see reason to panic yet, to be honest The belt doesn't disintegrate, doesn't heat up and doesn't put any more rubber on the rollers. Just on that initial run. I don't want to start changing parts before I figure out what's to blame.

In fact, I thought I got it right this time. Everything looked nice and smooth for 5-10 minutes. Then I revved the engine and kept it there for few seconds - the belt started to slip off to the side again. Argh.

So yeah, square 1. I'll see if I can find anyone to look at it, probably.

This one is a Federal-Mogul AE belt.

Grandpa#3

Hello MXM, Start over and read clarks garage write up on the cam belt at the link below. Go to "C" and click on it. Cam Belt tension is 40 in. lbs. and the Balance Belt is only 28 in. lbs., so it will feel loose. You could try belts made by Gates or Contitech.

http://www.clarks-garage.com/shop-ma...ure-index3.htm

Cheers,
Larry