lifter collapsed, engine is gone
Melting Slicks
Joined: Jan 2006
Posts: 2,713
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Let's work through this one. I do agree with your comment, but if the lifter is collapsed, then the preload on that end of the pushrod is now gone. The pushrod can move up and down as there is no longer any tension on it to hold it firmly against the top of the lifter or the bottom of the rocker arm. Spinning at only a few thousand rpm, the lifter goes up (it is not stuck, just collapsed) and slaps the end of the pushrod and then the pushrod slaps the bottom of the rocker. Since the preload is gone, this all happens at the wrong timing sequence and you can end up with a bent pushrod and/or a valve hitting a piston as the geometry is now all thrown off. I have seen this exact failure on a few Harleys. And the LS engines are still nothing but fancy pushrod engines, just like Harley's.
Simply - no.
Safety Car
Joined: Aug 2007
Posts: 4,836
Likes: 9
From: Rushsylvania Ohio
Yes, simply yes. I have way too much experience in both building engines and diagnosing failures/problems to argue with you guys. Hope the OP gets his new engine soon and gets back on the road. Good night guys. Hope you all can make it down to the Bash next week!
Melting Slicks
Joined: Feb 2004
Posts: 3,307
Likes: 111
From: Tucson AZ
Usually, any form of valve train damage is caused by valve float which is usually caused by insufficient spring pressure. This results in a hammer effect and breaks parts. Hydraulic lifters have a small piston held open by oil pressure. When they collapse, the small piston is depressed leaving excessive clearance (lash) in the valve train. When you hear a lifter making excessive clattering noise, you are hearing the hammering effect caused by excessive clearance.
After a lifter breaks, it usually has to be hammered out of the lifter bore. If the lifter bore is not cracked, they can be machined and sleeved back to std size with a bronze bushing. Most race blocks have all the lifter bores machined with a BHJ fixture and then sleeved back to size.
After a lifter breaks, it usually has to be hammered out of the lifter bore. If the lifter bore is not cracked, they can be machined and sleeved back to std size with a bronze bushing. Most race blocks have all the lifter bores machined with a BHJ fixture and then sleeved back to size.
Melting Slicks
Joined: Jan 2006
Posts: 2,713
Likes: 0
This "out of sequence" valve action you are talking about due to a faulty cam follower... as you say, not worth arguing about, but you might want to think it through on your own, on your own time. Vito's info, BTW, is right on.
Last edited by TrackNoob; Apr 14, 2008 at 11:35 PM.
Drifting
Joined: Jul 2005
Posts: 1,969
Likes: 8
From: NJ
Something similiar happened to mine. I broke the roller off the lifter which caused all kinds of hell. 404 and over 500 rwhp later couldn't be happier. I'm running Morels now. I suggest you do the same. I don't do Comps and I was not going to run GM again. Pay the scratch for the Morels or however they are spelled.
Racer
Joined: Feb 2008
Posts: 282
Likes: 11
From: Richmond Virginia
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Pro
Joined: Mar 2008
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From: Vancouver Island British Columbia
Something is wrong with this picture, I just can't see how a collapsed lifter doing all that damage, I gould get a second opinion. A colapse lifter? valves bent? timing chain gone. I can understand the damage from over reving, but not from a collapsed lifter, or maybe it was explained wrong.
Thread Starter
Safety Car
Joined: Dec 2004
Posts: 4,477
Likes: 2
From: Boca Raton, FL
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14
Safety Car
Joined: Apr 2006
Posts: 4,254
Likes: 5
From: Anaheim Hills, Ca
Let's work through this one. I do agree with your comment, but if the lifter is collapsed, then the preload on that end of the pushrod is now gone. The pushrod can move up and down as there is no longer any tension on it to hold it firmly against the top of the lifter or the bottom of the rocker arm. Spinning at only a few thousand rpm, the lifter goes up (it is not stuck, just collapsed) and slaps the end of the pushrod and then the pushrod slaps the bottom of the rocker. Since the preload is gone, this all happens at the wrong timing sequence and you can end up with a bent pushrod and/or a valve hitting a piston as the geometry is now all thrown off. I have seen this exact failure on a few Harleys. And the LS engines are still nothing but fancy pushrod engines, just like Harley's.
Race Director
Joined: Oct 2004
Posts: 10,089
Likes: 14
Here we go... lifter collapses and then valve(s) in that cylinder hit piston. Valve snaps off or is bent to one side and piston comes up and smacks it and comes to a violent stop (bent rod). Other cylinders keep trying to spin crankshaft and timing chain, but cam can not spin because rocker arms for the bad cylinder can not move. Timing chain now shears off teeth and the rest of the valvetrain begins to come apart, go out of time and other valves hit other pistons and the block quickly turns to junk. Lucky the crank did not snap in half. And all the above just happened in the blink of an eye. Yes, a collapsed lifter can destroy and engine.
A lifter collapse produces the same symptoms as opening up the lash on a mechanical lifter engine, or putting in a milder cam. Lifter collapse can never cause valve excursion outside the original limits of the installed cam.
Now spring failure, keeper failure, or the timing chain jumping teeth and altering the basic mechanical timing of the engine can cause a valve to contact the piston, but simple lifter collapse cannot. If I had to guess, I'd guess the basic culprit here was timing chain sprocket failure. Chevy uses a non-metallic sprocket in the small block timing set to make it run quieter. Normally, that's fine, and will last the life of the timing chain. But in a heavily hotrodded engine, there's a very good chance it will fail prematurely allowing engine mechanical timing to jump enough to cause catastrophic engine damage. Smart engine builders always replace the timing set with a good strong aftermarket replacement to prevent this sort of failure.
Last edited by shopdog; Apr 15, 2008 at 07:45 PM.
Safety Car
Joined: Aug 2007
Posts: 4,836
Likes: 9
From: Rushsylvania Ohio
No, it can't. As others have noted, a collapsed lifter cannot cause the sequence you describe. First of all, a collapsed lifter means its associated valve will open later, close earlier, and lift much less off of its seat than normal. Thus there is no way it can hit the piston. To hit the piston requires a valve to lift earlier, lift higher, or close later than normal, none of which a lifter collapse can cause.
A lifter collapse produces the same symptoms as opening up the lash on a mechanical lifter engine, or putting in a milder cam. Lifter collapse can never cause valve excursion outside the original limits of the installed cam.
Now spring failure, keeper failure, or the timing chain jumping teeth and altering the basic mechanical timing of the engine can cause a valve to contact the piston, but simple lifter collapse cannot. If I had to guess, I'd guess the basic culprit here was timing chain sprocket failure. Chevy uses a non-metallic sprocket in the small block timing set to make it run quieter. Normally, that's fine, and will last the life of the timing chain. But in a heavily hotrodded engine, there's a very good chance it will fail prematurely allowing engine mechanical timing to jump enough to cause catastrophic engine damage. Smart engine builders always replace the timing set with a good strong aftermarket replacement to prevent this sort of failure.
A lifter collapse produces the same symptoms as opening up the lash on a mechanical lifter engine, or putting in a milder cam. Lifter collapse can never cause valve excursion outside the original limits of the installed cam.
Now spring failure, keeper failure, or the timing chain jumping teeth and altering the basic mechanical timing of the engine can cause a valve to contact the piston, but simple lifter collapse cannot. If I had to guess, I'd guess the basic culprit here was timing chain sprocket failure. Chevy uses a non-metallic sprocket in the small block timing set to make it run quieter. Normally, that's fine, and will last the life of the timing chain. But in a heavily hotrodded engine, there's a very good chance it will fail prematurely allowing engine mechanical timing to jump enough to cause catastrophic engine damage. Smart engine builders always replace the timing set with a good strong aftermarket replacement to prevent this sort of failure.
Done for today. You guys can have fun and keep telling me I'm wrong all night if you desire, but how is that helping the OP?
Melting Slicks
Joined: Apr 2008
Posts: 2,814
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From: Some where in Amerika, sadly watching how is turned into a Socialist Republic.
LS2 warned you
After reading all the posts, and some very good points from many members, I went back to one of your answers.
LIFTER WAS TICKING FOR A MONTH, weather the lifter caused it or not, and I don't think it did, you ignored it, engines, specially highly modified units like yours can't be ignored when the engine tone changes.
Leasons learned here. Good luck with your new engine, whom ever you choose to built it.
LIFTER WAS TICKING FOR A MONTH, weather the lifter caused it or not, and I don't think it did, you ignored it, engines, specially highly modified units like yours can't be ignored when the engine tone changes.
Leasons learned here. Good luck with your new engine, whom ever you choose to built it.
Thread Starter
Safety Car
Joined: Dec 2004
Posts: 4,477
Likes: 2
From: Boca Raton, FL
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14
Lots of ideas being postulated, unfortunately we cannot pinpoint the exact cause. Here is what happened and what we have found so far:
What happened:
driving at 15mph, car was warmed up, going around a 90 degree corner, car loses power, engine dies and then it backfires. See my sig for my mods.
What we found so far (in no particular order):
bent valves, nicked piston faces, broken timing chair, roller sheared off a lifter, bore hole for broken lifter (in cam opening) has a 1"x1/16" sliver of block chipped out, cam looks OK.
Here's what I've requested:
402/403 short block, new cam, replace the bent valves in my AFR225 heads, put the sucker back together, including my D1SC. Put a temp tune on it so I can drive it for 500 miles, then do a real tune.
Now, any new ideas about the sequence of events that is going to cost me plenty?
Stay tuned.
Jeff
What happened:
driving at 15mph, car was warmed up, going around a 90 degree corner, car loses power, engine dies and then it backfires. See my sig for my mods.
What we found so far (in no particular order):
bent valves, nicked piston faces, broken timing chair, roller sheared off a lifter, bore hole for broken lifter (in cam opening) has a 1"x1/16" sliver of block chipped out, cam looks OK.
Here's what I've requested:
402/403 short block, new cam, replace the bent valves in my AFR225 heads, put the sucker back together, including my D1SC. Put a temp tune on it so I can drive it for 500 miles, then do a real tune.
Now, any new ideas about the sequence of events that is going to cost me plenty?
Stay tuned.
Jeff
Thread Starter
Safety Car
Joined: Dec 2004
Posts: 4,477
Likes: 2
From: Boca Raton, FL
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14
After reading all the posts, and some very good points from many members, I went back to one of your answers.
LIFTER WAS TICKING FOR A MONTH, weather the lifter caused it or not, and I don't think it did, you ignored it, engines, specially highly modified units like yours can't be ignored when the engine tone changes. Leasons learned here. Good luck with your new engine, whom ever you choose to built it.
LIFTER WAS TICKING FOR A MONTH, weather the lifter caused it or not, and I don't think it did, you ignored it, engines, specially highly modified units like yours can't be ignored when the engine tone changes.
Leasons learned here. Good luck with your new engine, whom ever you choose to built it.
