Help. Timing Chain Broke. What next?
Thread Starter
Racer
Joined: Mar 2008
Posts: 470
Likes: 6
From: Easley Sc
Help. Timing Chain Broke. What next? Update!
While on the track at about 100mph in 4th my timing chain broke at the time the car just died and had no idea what happened. The car is a 00 ls1 vette. Got home and determined it was the chain . I have the old chain off and I bought a c5r chain from katack. I was hoping I would be the luckiest sob in the world and not have any other damage.
My questions are can I put the car back together and check compression to determine any valve ,piston or other damage or should I go ahead and take off the heads to check. And what are the chances of getting away with only replacing the chain.
Just got the chance to dive back in. After the #2 cylinder showed zero compression did not have to go any farther with the compression test. Pulled heads and it appears that at least 4 intake and 4 exhuast valves were bent. I had a scar in the top of each piston that was hit but not very deep. Should be able to buff out. So the block was fine . The heads are at the machine shop now and they appeared to be fine except for the bent valves.
My questions are can I put the car back together and check compression to determine any valve ,piston or other damage or should I go ahead and take off the heads to check. And what are the chances of getting away with only replacing the chain.
Just got the chance to dive back in. After the #2 cylinder showed zero compression did not have to go any farther with the compression test. Pulled heads and it appears that at least 4 intake and 4 exhuast valves were bent. I had a scar in the top of each piston that was hit but not very deep. Should be able to buff out. So the block was fine . The heads are at the machine shop now and they appeared to be fine except for the bent valves.
Last edited by billy25us; Jan 7, 2010 at 05:55 PM.
Tech Contributor
Joined: Jan 2007
Posts: 19,401
Likes: 1,143
From: Dyer, IN
While on the track at about 100mph in 4th my timing chain broke at the time the car just died and had no idea what happened. The car is a 00 ls1 vette. Got home and determined it was the chain . I have the old chain off and I bought a c5r chain from katack. I was hoping I would be the luckiest sob in the world and not have any other damage.
My questions are can I put the car back together and check compression to determine any valve ,piston or other damage or should I go ahead and take off the heads to check. And what are the chances of getting away with only replacing the chain.
My questions are can I put the car back together and check compression to determine any valve ,piston or other damage or should I go ahead and take off the heads to check. And what are the chances of getting away with only replacing the chain.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
I would be really surprised to find out that only the chain broke. First step I would take is pull the valve covers and rocker arms. Put a straight edge across the valve stems and see if the are all in line as bent valves will not come up all the way. I would plan on pulling the heads though. The chances of not bending a valve (likely more than one) under those conditions are close to zero. I think you will be a "lucky sob" if the pistons are OK.
MFIC
Joined: Aug 2005
Posts: 1,997
Likes: 14
From: Charlotte, North Carolina
I would be really surprised to find out that only the chain broke. First step I would take is pull the valve covers and rocker arms. Put a straight edge across the valve stems and see if the are all in line as bent valves will not come up all the way. I would plan on pulling the heads though. The chances of not bending a valve (likely more than one) under those conditions are close to zero. I think you will be a "lucky sob" if the pistons are OK.
Team Owner
Joined: Jul 2004
Posts: 24,652
Likes: 298
From: NJ
St. Jude Donor '05-'08
lucky would be an understatement if you only broke the chain.
you should take it all down and see what other problems there might be. I would suspect rod(s) and valve(s) at the least. If the valve is messed the piston(s) are probably going to need to be replaced. Hopefully the heads didnt get hit.
After I broke my timing chain a few years ago we did alot of research in this area. Some times we found it was the timing chain, but many times we found it was some other part of the valve train that actually was the cause and the timing chain just happen to go too.
you should take it all down and see what other problems there might be. I would suspect rod(s) and valve(s) at the least. If the valve is messed the piston(s) are probably going to need to be replaced. Hopefully the heads didnt get hit.
After I broke my timing chain a few years ago we did alot of research in this area. Some times we found it was the timing chain, but many times we found it was some other part of the valve train that actually was the cause and the timing chain just happen to go too.
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Melting Slicks
Joined: Dec 2003
Posts: 3,315
Likes: 17
From: Near Jacksonville Fl.
While on the track at about 100mph in 4th my timing chain broke at the time the car just died and had no idea what happened. The car is a 00 ls1 vette. Got home and determined it was the chain . I have the old chain off and I bought a c5r chain from katack. I was hoping I would be the luckiest sob in the world and not have any other damage.
My questions are can I put the car back together and check compression to determine any valve ,piston or other damage or should I go ahead and take off the heads to check. And what are the chances of getting away with only replacing the chain.
My questions are can I put the car back together and check compression to determine any valve ,piston or other damage or should I go ahead and take off the heads to check. And what are the chances of getting away with only replacing the chain.
Drifting
Joined: Jan 2004
Posts: 1,419
Likes: 6
From: Alamosa CO
Make lemonade from the lemons, get the heads milled a bit to up the compression, have them ported and definitely put some new springs and valve seals on them. Better change the pushrods too. 
Good luck!
Jimbo
Good luck!
Jimbo
Race Director
Joined: Aug 2004
Posts: 14,639
Likes: 39
From: Winston-Salem North Carolina
St. Jude Donor '08-'09
While on the track at about 100mph in 4th my timing chain broke at the time the car just died and had no idea what happened. The car is a 00 ls1 vette. Got home and determined it was the chain . I have the old chain off and I bought a c5r chain from katack. I was hoping I would be the luckiest sob in the world and not have any other damage.
My questions are can I put the car back together and check compression to determine any valve ,piston or other damage or should I go ahead and take off the heads to check. And what are the chances of getting away with only replacing the chain.
Just got the chance to dive back in. After the #2 cylinder showed zero compression did not have to go any farther with the compression test. Pulled heads and it appears that at least 4 intake and 4 exhuast valves were bent. I had a scar in the top of each piston that was hit but not very deep. Should be able to buff out. So the block was fine . The heads are at the machine shop now and they appeared to be fine except for the bent valves.
My questions are can I put the car back together and check compression to determine any valve ,piston or other damage or should I go ahead and take off the heads to check. And what are the chances of getting away with only replacing the chain.
Just got the chance to dive back in. After the #2 cylinder showed zero compression did not have to go any farther with the compression test. Pulled heads and it appears that at least 4 intake and 4 exhuast valves were bent. I had a scar in the top of each piston that was hit but not very deep. Should be able to buff out. So the block was fine . The heads are at the machine shop now and they appeared to be fine except for the bent valves.
I hope you have better luck then I did. BTW, both times this happened I was in 4th gear on a track around 140-147mph. We tend to think that the on the throttle/off the throttle/ on again allows the chain to flex enough to cause the breakage. Look into the chain tensioner/flex stops that the LS7's have. I believe the ls6 blocks already have the threaded holes for mounting.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Yes, they have the holes. Unfortunately, the timing chain damper is no longer made for the LS1/LS6 blocks except for later 04 blocks where the hole spacing was changed and the LS2 timing chain damper will fit. There is a known harmonic issue with the timing chain and hence the reason the damper was developed.
4th Gear
Joined: Jan 2010
Posts: 4
Likes: 0
lucked out
We just had a timing chain start loosing all the links. Found this out when, car DROVE into bay for plugs and oil change. When I removed the drain plug, out came a train of rollers and links stuck to the drain plug.
No, the chain never broke.
That's luck.
No, the chain never broke.
That's luck.
Safety Car
Joined: Nov 2002
Posts: 4,394
Likes: 6
From: Melbourne FL
If there was a link connected to your oil drain plug the chain must have broken. You can't loose a link of the chain and the chain still be intact. I bet the rollers are from your rocker arms and not the timing chain.
Tech Contributor
Joined: Jan 2007
Posts: 19,401
Likes: 1,143
From: Dyer, IN
Please post pics of the links you pulled from the oil pan.
4th Gear
Joined: Jan 2010
Posts: 4
Likes: 0
pics requested
this is what I found.
TIC TOC..
this is where it came from.....
and if you still don't believe.....here's a pic of the sloppy chain on the engine. still in disbelief. Why do these do this again?
chalk this one up to; "why you don't........"