mbonner

Need some advice here. My timing belt, just 2 summers old, broke while driving at 80km/hr.

My mechanic just called and said the belt broke because it wore away on the cover side of the belt and was only 3/8" thick when it broke. The motor side of the belt was not worn. The rollers are 2 years old as is the waterpump and failed timing belt.

What could have the belt been rubbing on to wear it like that? Anyone have experience of this happening? Quote is $2.200 to fix everything. Labour and parts.

Mike

BeerBurner

Am I reading this right? The belt that was almost an inch wide word down to that little?

Unless the belt migrated that way, I can only imagine that something was screwed up during installation.

BB.

xsboost90

ouch- sounds like something wasnt installed right and the belt was riding forward- sometimes this happens from rollers being installed backwards and it lets the belt rub the cover.

mbonner

He checked the belt last fall before I put it away for the winter. Fine for tension and appearance. 4 bent exhaust valves, no other damage, I was lucky the head and pistons were fine.
Mike

Yabo

well, generally when people say they 'need a new head' because of timing belt failure, it is because of the broken valves .
Do you have a late waterpump? I know you need a different cover if you have late one, or a cut out of it. Don't know if that does anything to the belt if you don't do it?

mbonner

Thanks, Devon, I assume it is a late waterpump, maybe that's it, I need a late cover to go with it.
I'll talk to the mech Monday, there must be some signs of rub on the inside of the cover.
Mike

Yabo

The early cover can be modified by cutting part of it, there's a picture somewhere, I don't know where though. I don't know exactly what happens, or if you could even get it together with the old cover on a new pump.. but that's at least a guess! Good luck.

mbonner

When I bought the car there was a hole cut crudely into the cover over the waterpump, you could see the waterpump boss through the hole. I could not figure out why. I replaced it, I bought a cover for an 83 and put that on to keep dust and sand out, so when we installed a new waterpump the old cover cut into the belt?
So maybe that hole was cut into the belt cover when I bought the car to clear the belt?
Anyone else care to chime in, apart from Devon, who I think has the answer?.
Mike

Yummybud924

that's why every now and then I remove the front covers and inspect the belts to see if anything strange is going on.

my belt was running forward over the camshaft sprocket and my porsche mechanic said it was fine. but then I found out the nut behind the tensioner had come loose and that was the cause of the belt riding forward so I fixed that.

that's why i'm getting my timing belt tensioner stud replaced soon also to prevent this.


if you are low on money you could always do it yourself / get a good used head for cheap / new headgasket set that should cost only a couple hundred bucks.

head replacement on a 944 doesn't look too difficult, just labour intensive.

Calmchaos

When I first bought my car my balance shaft belt rode forward enough to break the thrust washers.
I'm pretty sure it is just due to the fact that the sprockets and rollers wore down and tiped over. This caused the belt to ride out.
Anyway, I just replaced my rollers and such and it solved that problem.

My timing belt tensioner stud (oil pump stud) just broke recently so I had to buy 8 new valves, and also opted to buy another head. I had the whole thing rebuilt by a machine shop. The whole ordeal cost me just under $500, including labor.

GL!

DarylJ

+1 It's not that bad. If you just replace the head and get on with it, it should only take several hours. If you do what I did, and start while-you're-in-thereing everything else, it can take a significant amount of time.

bjzorn

I run without the top front belt cover so I can inspect and adjust as needed. Then again the car is not my daily driver, so I feel safe doing so

mbonner

The garage owner told me when he was giving me a report and estimate repairs, that Vince, the mech, suggested I drive with the top cover off if he thinks the rollers, etc are OK and watch the belt. Not likely a stone could find its way off the road into the bottom cover, is it?. I have to drive 5 miles down a gravel road to get to my farm. But I can always duct-tape some bug screen over the top until we figure out what the problem is, so what year top cover do I need if I have a late pump as Devon suggests?
Mike

Erzengal

When a 944 goes from Early to Late Style Water Pump, the Porsche Docs say to take a cutting wheel to the old Belt Covers, creating a diamond shaped hole. A early, non-modified cover will contact parts of the Timing Belt area causing issues.

PS, make sure you take 944's to places that have worked on them before, not just Porsche shops, or Euro shops. There are some oddities in our cars that can cause issues from unexperienced mechanics.

mbonner

That's what I need to know,does anyone have a pic of a cover with a hole so we know where to cut it?
Thanks,
Mike