Bottom feeder feasts on 89GT. It was -- tasty
#76
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"This too casual usage seems to perpetuate the wide-spread-outside-of-928-cognoscenti-world the false impression that the timing belt is the only thing that needs to be changed during a belt service when in fact it is usually the least critical item that needs to be serviced, replaced or at least inspected."
I could not agree more - it always worries me when a customer orders "A" timing belt. How many cars for sale with the statement "timing Belt changed" and then you see the receipt for the work, and guess what, that is the only part they changed. If a belt snaps it is always another part that causes the breakage.
I cannot ever remember hearing of a belt breaking with no other part involved.
I could not agree more - it always worries me when a customer orders "A" timing belt. How many cars for sale with the statement "timing Belt changed" and then you see the receipt for the work, and guess what, that is the only part they changed. If a belt snaps it is always another part that causes the breakage.
I cannot ever remember hearing of a belt breaking with no other part involved.
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
#77
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For the cases you’ve come across what was the ‘pathology’ of the broken belt?
Serious question this; I’d like to learn about additional failure modes that I may never have heard about.
#78
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Dave - I doubt I can count them on one hand - extremely rare. More cases where the belt strips teeth because the WP seizes or bad maintenance practices - belt too tight or too slack.
The more I dig into the gray matter, the less I remember of an actual case of the belt snapping. Everything I can remember, that was catastrophic, the belt did not break. Maybe Sean, GB, DR or Mark A have a story to tell.
The more I dig into the gray matter, the less I remember of an actual case of the belt snapping. Everything I can remember, that was catastrophic, the belt did not break. Maybe Sean, GB, DR or Mark A have a story to tell.
#79
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Brings back the horror story from Porsche club meet a few years ago. Guy rolls up in a 928, just getting dark, we look down in the air tube well on the pax side and 'holy-mother-of-god!' all we saw were a few threads left in there of what used to be a timing belt. I was - gobsmacked. Towed home, survived another day.
#80
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I have had one belt *break* on a 944S (it was a type 00 belt installed by Porsche) and the symptom was engine running at low RPMs then stopping. No smoke, no noise, no muss, fine water pump. It sheared several teeth and broke, requiring several new valves and a refresh.Porsche redesigned the belt after 87, my guess is they ported the fixes over to the 32v belt as well.
Never had an .02 or better belt break since. I did have the tensioner pad crack, destroying the head, but that's another problem. Never had a balance shaft belt break (not on 928 of course) but have heard of one breaking then taking out the timing belt.
Edit: Even when the tensioner pad cracked, broke off the head, took a chunk of head with it, and the chain ripped off most of the teeth on one camshaft the .02 belt did not break or shear. Granted I *did* replace it when I spent a year fixing the whole resulting mess myself but it was not broken.
Yours for "30 years of Porsche ownership data" on the 4v engine types.
Never had an .02 or better belt break since. I did have the tensioner pad crack, destroying the head, but that's another problem. Never had a balance shaft belt break (not on 928 of course) but have heard of one breaking then taking out the timing belt.
Edit: Even when the tensioner pad cracked, broke off the head, took a chunk of head with it, and the chain ripped off most of the teeth on one camshaft the .02 belt did not break or shear. Granted I *did* replace it when I spent a year fixing the whole resulting mess myself but it was not broken.
Yours for "30 years of Porsche ownership data" on the 4v engine types.
#81
I've seen 3 928's where the crank peeled off some teeth, 2 of them were early cars where the belts appeared to be original and the cars were parked for decades and then attempted to start. On one of them the teeth were semi intact, and just stripped off the belt.
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The more I dig into the gray matter, the less I remember of an actual case of the belt snapping. Everything I can remember, that was catastrophic, the belt did not break. Maybe Sean, GB, DR or Mark A have a story to tell.
I also remember seeing Rennlist pictures of a severely dry-rotted ~30-year-old belt taken at one of your gatherings. Might be the same one DocM's writing about.
So.... *extreme* age, or accelerated aging due to storage conditions, or someone trying really really hard to get the belt to actually snap...
Maybe Mark can tell us about a not-too-old belt just 'snapping' for no apparent reason.
#83
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I also remember seeing Rennlist pictures of a severely dry-rotted ~30-year-old belt taken at one of your gatherings. Might be the same one DocM's writing about.
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#85
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The Gates HTD belt is the same belt used in Harley-Davidson motorcycles. That's a fact, ask Gates and they will tell you it's the same belt, construction wise. The only difference is the width and length. Even the teeth are the same size. Detergent oil will cause the belt to deteriorate, they generally don't break, the teeth will shred as the belt delaminates. They're really almost indestructible.
Back in the late 60's the early belts were square toothed, and came off a lot, very unreliable. When the tooth was changed to the rounded bottom, the belts became very reliable, didn't stretch like a chain would.
Back in the late 60's the early belts were square toothed, and came off a lot, very unreliable. When the tooth was changed to the rounded bottom, the belts became very reliable, didn't stretch like a chain would.
#86
A shop here locally kept some of the timing belt teeth in a baby food jar on the counter. The owner would pick it up, take off the lid and dump out the the teeth onto the counter to show people who would not ante up for a timing belt service. He would also take a new timing belt out of a box and show it to customers and explain that they would want to buy a new car when the teeth came off and they saw the repair bill from the damage. He would simply tell them that he will make more money if the belts break but he would rather keep his customers long term.
#87
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I was struck by this enough to take a picture of it, burn car at Mark's. Those belts are tough:
#88
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I'm scheduled to replace the 928S belt in another 15k miles or so, I could just run it till it breaks :-)
#89
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Pretty sure the same car at the OCIC in Dallas way back. One owner car with IIRC 47k miles. The belt had not been changed since the car was new. The belt was badly cracked but the radial fibers were still very much in place and still holding the belt together. How long it would have lasted if peer pressure had not made the owner flat bed it to Sean's place is anyone's guess. It never snapped!!! Same car was totaled a few years later and the owner nearly killed - the car saved him. If he had been driving one of his other cars it would have resulted in his death - very lucky guy.
#90
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Hey Doc: I mentioned your Bonanza purchase to a couple of aviation-minded friends on FB and they're quite jealous. They also said something to the effect that until it was upgraded with new electronics you wouldn't be able to fly IFR. They thought cost on this upgrade was in the $5k range (which still seems cheap, all up). Is that your plan?