Another Timing Belt Failure - But All is Well
11-13-2008, 12:53 PM
#31
Drifting
Porsches are engineered to push the performance envelope.
That comes with a price. ANY car that's 20-25 years old will require a lot of maintenance. Any performance car will require more.
You should see what repair bills are on a 20 year old Ferrari Testarossa. It would be cheaper to just buy another 944 every month.
That comes with a price. ANY car that's 20-25 years old will require a lot of maintenance. Any performance car will require more.
You should see what repair bills are on a 20 year old Ferrari Testarossa. It would be cheaper to just buy another 944 every month.
common now, a ferrari with a mid mounted v12 engine is a little different than a 944 na 4 banger. This car is not not much different in performance than a nissan 240sx except that everything costs 10 times more.
11-13-2008, 01:02 PM
#32
Nordschleife Master
Thread Starter
A machine shop should take 1-2 days, and you may want to ask 944online about what happens to the core charge when they find bent valves. You may not get the full core charge back.
$600 is pretty steep for a head rebuild. Typically machine shops will charge $30-$50 per valve, and ~$150 for a full head rebuild (including guides and seals), so in my $300 estimate that is 3-5 bent valves (Depending on pricing).
It's your car and if you are in a rush then take the quick route, but I'd still suggest calling some machine shops. Maybe the pricing down there is totally different and my advice is irrelevant.
$600 is pretty steep for a head rebuild. Typically machine shops will charge $30-$50 per valve, and ~$150 for a full head rebuild (including guides and seals), so in my $300 estimate that is 3-5 bent valves (Depending on pricing).
It's your car and if you are in a rush then take the quick route, but I'd still suggest calling some machine shops. Maybe the pricing down there is totally different and my advice is irrelevant.
11-13-2008, 11:59 PM
#33
Drifting
Weren't you the same person that in another thread you were arguing with me when I said these aren't daily driver cars due to their old age and parts availability issues? Remember that conversation? You said something like washing and waxing and changing the oil were all that was needed or something like that?
Hmm.
They grow up so fast.
Hmm.
They grow up so fast.
lol I never said washing and waxing it was all that was needed..
I've had my car for 3 years now so I know maintenance is expensive. The first thing I did when I bought my car 3 years ago was change all the belts, rollers, water pump and front engine oil seals before I even started driving it, and the pervious owner had told me the belts were already done.
and now I have to do the belts again soon.
but when I tell people i have to change my timing belt every 3 years they are shocked. No one else that I know of changes timing belts that often on their car.
with 944s I keep on hearing about timing belt failures and people are changing them more often than on other cars.
I do my preventative maintenance but all this timing belt disasters are making me paranoid. The next thing I'm going to do is buy a spare cylinder head just incase I break a belt.
11-14-2008, 01:55 AM
#35
Drifting
I changed my dme relay in the summer and kept the old one in the glove compartment.
11-14-2008, 02:59 AM
#36
RL Community Team
Rennlist Member
Rennlist Member
Damn, we lost another one.
Sorry Mike. I have no idea why your belt failed. My 968's timing and BS belts were only 2.5 years old with about 20k miles and the BS belt snapped, and jammed the timing belt. I lost 2 valves. I looked over the cam timing charts and it turns out the absolute best-case scenario with the 968 is 2 bent valves, could be much more. Whew I think.
I had retensioned the belts a few months before failure. I set the BS belt too tight, slightly. Maybe that caused it? I think it's mainly just the **** Conti belt quality. I will only buy and use Porsche belts from now on. A valve job on a 16v head has put a hole in my pocket the size of Neptune.
Sorry Mike. I have no idea why your belt failed. My 968's timing and BS belts were only 2.5 years old with about 20k miles and the BS belt snapped, and jammed the timing belt. I lost 2 valves. I looked over the cam timing charts and it turns out the absolute best-case scenario with the 968 is 2 bent valves, could be much more. Whew I think.
I had retensioned the belts a few months before failure. I set the BS belt too tight, slightly. Maybe that caused it? I think it's mainly just the **** Conti belt quality. I will only buy and use Porsche belts from now on. A valve job on a 16v head has put a hole in my pocket the size of Neptune.
11-14-2008, 03:18 AM
#37
Drifting
I use Gates belt whic is the "porsche" belt I think. conti is listed as aftermarket.
but my balance shaft belt is contitech I believe because the "porsche" balance shaft belt which might be gates is like 250 bucks or something crazy like that. I'm not paying 250 bucks for a belt. I'd rather replace it more often.
but my balance shaft belt is contitech I believe because the "porsche" balance shaft belt which might be gates is like 250 bucks or something crazy like that. I'm not paying 250 bucks for a belt. I'd rather replace it more often.
11-14-2008, 03:27 AM
#38
Drifting
I forgot to mention, all this timing belt scare from the 944 crowd made me so paranoid that I even replaced my camshaft and crankshaft sprockets when I changed my belts because I heard that a old sprocket with the protective coating worn off will wear out the timing belt faster?
11-20-2008, 11:22 AM
#39
Nordschleife Master
Thread Starter
Thanks for all the comments and advise. Just to finish off with some pictures and the outcome of this problem.
To recap, belts changed 12,500 miles (18 months) ago. Front seals, rollers, water pump changed at the same time. Belts were retensioned after 2000 miles, everything to the book by a competant mechanic. Factory (conti) belt dated 10/06. Belt failed with car stationary at idle.
With the covers removed there were zero oil leaks.
With the belts removed all the rollers, tensioners and the water pump turned with no play or resistance.
The balance belt still looked like new.
The timing belt was not frayed anywhere along it's length.
There was a portion of the timing belt (6-8in long) where the teeth had completely come off.
On further inspection a lot of the other teeth close to that area were about to come off, covering about half the belt.
The rest of the belt had the teeth intact and even where the teeth had come off, the actual belt was fine.
My only conclusion is a faulty belt - Again this was a factory belt bought from a dealer - I am pissed.
Result: 2 bent valves
Here are the pics:
No damage to the pistons...
Two bent valves...
One only slightly bent...
One a little more bent...
Section of stripped teeth...
Transition from stripped to ok...
The new belt (same as the old - but date code 11/07)...
Should I take this further and inform the dealer or Conti?
To recap, belts changed 12,500 miles (18 months) ago. Front seals, rollers, water pump changed at the same time. Belts were retensioned after 2000 miles, everything to the book by a competant mechanic. Factory (conti) belt dated 10/06. Belt failed with car stationary at idle.
With the covers removed there were zero oil leaks.
With the belts removed all the rollers, tensioners and the water pump turned with no play or resistance.
The balance belt still looked like new.
The timing belt was not frayed anywhere along it's length.
There was a portion of the timing belt (6-8in long) where the teeth had completely come off.
On further inspection a lot of the other teeth close to that area were about to come off, covering about half the belt.
The rest of the belt had the teeth intact and even where the teeth had come off, the actual belt was fine.
My only conclusion is a faulty belt - Again this was a factory belt bought from a dealer - I am pissed.
Result: 2 bent valves
Here are the pics:
No damage to the pistons...
Two bent valves...
One only slightly bent...
One a little more bent...
Section of stripped teeth...
Transition from stripped to ok...
The new belt (same as the old - but date code 11/07)...
Should I take this further and inform the dealer or Conti?
11-20-2008, 12:54 PM
#40
Race Car
Yes I think you should because you have nothing to lose. The belt looks new as the backside letters are still like new. I doubt they will cover your engine damage but maybe you can get a lifetime supply of belts.
11-20-2008, 01:34 PM
#41
Rennlist Member
I'm curious to how the rest of the belt looks at the portion where the teeth weren't stripped off. There was another thread very recently where someone suffered the same fate, but the whole belt looked worn down to the point where the teeth had nothing to hold on to.
Someone had a good point about looking in the valve train for something that might have jammed the cam. Did you find anything in there?
It is most disturbing to have a failure when you follow everything to the book. That's just not fair! I would check the valve guides on the two valves that got bent to make sure the head didn't crack in that area. Since the failure happened at idle, damage isn't likely, but I'd would make sure.
Someone had a good point about looking in the valve train for something that might have jammed the cam. Did you find anything in there?
It is most disturbing to have a failure when you follow everything to the book. That's just not fair! I would check the valve guides on the two valves that got bent to make sure the head didn't crack in that area. Since the failure happened at idle, damage isn't likely, but I'd would make sure.
11-20-2008, 01:47 PM
#43
Nordschleife Master
Thread Starter
I'm curious to how the rest of the belt looks at the portion where the teeth weren't stripped off. There was another thread very recently where someone suffered the same fate, but the whole belt looked worn down to the point where the teeth had nothing to hold on to.
Someone had a good point about looking in the valve train for something that might have jammed the cam. Did you find anything in there?
It is most disturbing to have a failure when you follow everything to the book. That's just not fair! I would check the valve guides on the two valves that got bent to make sure the head didn't crack in that area. Since the failure happened at idle, damage isn't likely, but I'd would make sure.
Someone had a good point about looking in the valve train for something that might have jammed the cam. Did you find anything in there?
It is most disturbing to have a failure when you follow everything to the book. That's just not fair! I would check the valve guides on the two valves that got bent to make sure the head didn't crack in that area. Since the failure happened at idle, damage isn't likely, but I'd would make sure.
The head is being completely rebuilt and there is nothing loose inside the cam tower or under the belt covers. I am convinced that this was a manufacturing defect of the belt.
11-20-2008, 01:49 PM
#44
Nordschleife Master
Thread Starter
11-20-2008, 02:42 PM
#45
Racer
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Check the stud that the roller is on. It might be slightly bent. I have seen a car that had the same symptoms that you had and this was the problem. The slight tilt in the roller will cause the teeth to start tearing off the belt from rear to front.