Ian928

My girlfriend and I changed belts + waterpump on her 89 944 turbo some months ago, and when we tightened the belts now, we could see that the belt did not track straight over the camshaft gear, but was riding towards the front of the engine. The belt is riding partly outside the camgear. Needless to say we are worried...

We did take the tensioner off, is it possible that we could have mounted it wrong? We did a search and found some speculations about the wheel on the waterpump also. It is after all the last wheel the belt touches before it goes to the camgear.

It is said on the 928 forum that wear on the camgear can cause the belt to track off center on the gears. Is this known for 944s also?

Kirsti and Ian in Norway
89 944 turbo
80 928S

sharky47

Did you put the tensioner on in the correct direction? There is a lip on one side of the water pump pulley and there is also a lip on one side of the tensioner pulley. The lips are supposed to be opposite of eachother - if they are on the same side the belt can walk into and contact the engine........I will be a man and admit this is how the belt failed on my 944S - completly my fault - expensive lessing in Porsche wrenching.

H2

This is a common concern..that is the belt riding towards the front of the cam gear. It if rides true and is back a ways from the gear edge, some have gone years and no change. Others...well...have ended up shopping for another engine. A search of the archives here will turn up quite a discussion of the possible problems that can contributed to this problem.

Personally, I'd find it difficult to change Tbelts with a girlfriend. How can you concentrate or think clearly?

Harvey

sharky47

I wish I had a girlfriend that would help me work on P-cars!

But yeah - if the belt is riding TOWARDS the engine you might have the same symptoms I failed to recognize on my "S" many years ago.

Ian928

I cannot see how this could happen? We did not disassemble the tensioner...

I just remembered, I took a couple of pictures! See: http://www.flickr.com/photo_zoom.gne...57594055719894
As you can see in the picture, there is a big gap between the edge of the waterpump pulley and the belt. This gap has now disappeared, the belt is running by the edge of the waterpump pulley and is now 25% outside the camgear... Help!



Well it seem none of us was able to think clearly when we did this... But yes, I am a lucky guy!

Kirsti and Ian in Norway
89 944 turbo
80 928S

FRporscheman

THIS ONE'S A KEEPER.

You should get a new water pump. Whoever rebuilt or manufactured that one you're using has put the gold pulley too far out. Just out of curiosity, what kind of gasket did you put on for the water pump? Was it a thick black cardboard kind or a thinner green plastic/paper kind? The gasket wouldn't make this much of a difference but I'm just curious.

Try to exchange your waterpump if you can, to save money.

cruise98

Check the location of the belt on the tensioner roller. I cannot see it in the picture. There is a lip that should be closest to the engine block. Is this the before picture?

Also, check the bolt holding the roller to the tensioner to be sure it is tight and not about to break.

Grab the water pump pulley and try to wiggle it. There should be zero free play, and when the belt is off, should turn smoothly.

Ian928

I will try my very best...

I have another picture, this is before we put on the belts: http://www.flickr.com/photos/21967367@N00/209434794/ It don't seem to be much of a gap between the pulley and the pump. Also, I believe I compared the two before we installed it. But you are right, is really seems that the edge of the pulley is to far out. Could it be that the camshaft has moved inwards or is this impossible?

You see the thickness of the gasket in the picture, I can't recall the colour but I believe it was not specially thick.

This is the after picture. I will check when I get the opportunity.

I do believe you may be onto something here. There is a lot of discussions on the 928 board regarding the belts and a lot of problems on 928e engines evidently comes from bent roller bolts. Also, it is said there that the belt should track in the middle of the gears by itself, the lips on the rollers is just an extra safety measure. We may in one way or another bent the bolt holding the tensioner roller, causing the roller to track the belt to the forward lip of the waterpump pulley.

I cheked when we installed and there was none...

Kirsti and Ian in Norway
89 944 turbo
80 928S

Ian928

I'm bumping this up again to ask if anyone can confirm that the timing belt run close to the lip on the waterpump pulley when it tracks correct.

This is how it looked when we installed it: http://www.flickr.com/photo_zoom.gne...57594055719894
Now the belt has moved forward to the lip on the waterpump pulley and is now running on the edge of the camgear.

I need to know if there is something wrong with the waterpump pulley before I do something more. I hope someone has an engine without covers or a picture of their timing belt and are willing to take a look?

Kirsti and Ian in Norway
89 944 turbo
80 928S

Chris White

it is possible that the water pump has a 3.0 pulley on it. The last 3.0 pump (brand new) I installed (yesterday!) had the 2.5 casting (which is the same). The 3.0 pulley is wider - is the belt hanging off the rear side of hte water pump pulley? If not you got a 3.0l pulley....

cruise98

I had thought of that, but the casting says 2.5L. The pump pulley does look kinda wide in the pictures though. What is the width of the 3.0 pulley?

Chris White

off the top of my head I would say about 30% wider - and the casting 'size' doesn't mean anything!

Mike C.

I have to agree that the water pump pulley looks suspect. The way the belt rides on the cam sprocket looks normal and I can't imagine how this could move fore/aft. The pulley does appear to be wider than what I'm used to seeing. Can you get in there to measure the pulley width? If so, I have a spare 2.5 L pump I can compare it to. I know that's a lot of work to get it back off of there so I hope it turns out to be something else....

cruise98

I have a used water pump from an 8v 2.5, and the pulley is 22mm wide from the backside of the lip to the edge. The wear marks are roughly 18mm wide.
The belt rides approximately 4 mm back from the front lip.

Ian928

I have not access to the car now, but this sounds like about the same pulley width and location of the belt on the pulley as when we installed the belt and WP. If the belt is 18mm the pulley looks to be roughly 22mm wide (according to the pictures). Or am I wrong?

Your comment confirms my suspicion that the belt is normally not riding close to the lip of the pulley. I suspect this means that the tensioner probably are forcing the belt away from the engine and the lip on the pulley has saved the engine from failure.

In the picture, the belt was not outside the pulley. Hmm... I just realised that according to Chris I am still not sure if the pulley is for a 2.5 or 3L engine. Still, there must be a force causing the belt to track forward to the lip of the pulley?

I guess we have to tear it all down to measure pulley width and make sure nothing is bent on the tensioner...

Kirsti and Ian in Norway
89 944 turbo
80 928S