Odds on a slipped timing belt....
#19
Rennlist Member
Lol, you guys are hilarious.
Tight tolerances or not, interference engines guarantee the valves and pistons colliding if the belt breaks.
Good luck with the repair.
Tight tolerances or not, interference engines guarantee the valves and pistons colliding if the belt breaks.
Good luck with the repair.
#21
Originally Posted by Serge944
Lol, you guys are hilarious.
Tight tolerances or not, interference engines guarantee the valves and pistons colliding if the belt breaks.
Tight tolerances or not, interference engines guarantee the valves and pistons colliding if the belt breaks.
#24
Race Car
I have seen and replaced over 50 heads from timing belt "slips" in 8v engines as they rarely ever break. All I have to say about not bending valves is that I will believe it when I see it. It has NEVER failed to bend valves. One time I was able to restart the 951 with a "slipped belt" but turned out to have low compression in one cylinder anyways. In a spec race car I have seen with the 9.5 stock compression with a radically shaved head, the valves bent (all 4 exhaust valves) WITHOUT any timing belt failure. The engine was way over revved from downshfting into the wrong gear from what I can tell. I ended up putting clay on the top of the piston and reassembling the top end to turn over the engine in order to see how far the valve is from the top of the piston at TDC. There was only a 4mm gap between the top of the piston and the closed valves. That is how tight it is in there.
#26
Race Car
The odds for ALL 4 cylinders to be at TDC at the same time is a physical impossibility, therefore something gets bent along the process. The only way the valves are not bent is if there was no cam in the car. I don't work with 16v engines but maybe the lift is not as high as 8v engines. 8v engines bend valves.
#27
When setting the cams on a 16v only two of the lobes actually touch the lifters. These two lobes are right on the edge of the lifters and compress maybe a mm at the most.
#28
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"So... How about odds on bottom end integrity??"
Well, chances are.........your ok. BUT.....if the engine was cranked, and cranked and cranked over a ton of times, and/or you have Mr. Murphy in your back pocket (he's my buddy, ya know), then you could open it up to see that a valve broke off the stem, and, well, that just doesn't do wonderful things to the cyl. walls, ya know. This is what the very first 944 car with a broken timing belt looked like inside when I took it apart (it became an engine swap after this, and is my avatar car). Not pretty. I can assure you, debris did score the hell out of this cylinder wall.
Well, chances are.........your ok. BUT.....if the engine was cranked, and cranked and cranked over a ton of times, and/or you have Mr. Murphy in your back pocket (he's my buddy, ya know), then you could open it up to see that a valve broke off the stem, and, well, that just doesn't do wonderful things to the cyl. walls, ya know. This is what the very first 944 car with a broken timing belt looked like inside when I took it apart (it became an engine swap after this, and is my avatar car). Not pretty. I can assure you, debris did score the hell out of this cylinder wall.
#29
I agree with everyone here so far. I would almost bet my left nut on it, you bent some valves. I just put mine back togather after I stripped some teeth. In my case it was only about four and from my tensioner going out, but I still manager to bend seven of eight for sure.
Pull the head and check your piston tops and walls. If you "got lucky" at all they will be ok and all you will need is a head job.
By the way go get a can of PB Blaster first.
Welcome to the game man.
Pull the head and check your piston tops and walls. If you "got lucky" at all they will be ok and all you will need is a head job.
By the way go get a can of PB Blaster first.
Welcome to the game man.
#30
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I bent two valves and while testing the car I put a different belt on to see if it still would run. It did run, but rather badly as it didnt have any compression in one or two cylinders. And those two valves got bent when the belt broke while accelerating from a stop. I got real lucky it was only 2 valves.