Blown engine
Thread Starter
3rd Gear
Joined: Feb 2010
Posts: 3
Likes: 0
From: Quakertown PA
Blown engine
Hi guys,
I need to ask what you all think of this sequence of events.
Had a valve spring break on the Z. All springs were replaced.
Then broke another spring within a week. That spring was replaced.
Then the engine blew. 7 and 8 clyinders.... two windows in the block.
The shop says it happens. Really?? After all these new springs?
Would anyone have looked a little closer after the second spring
breakage? I don't know much about internal workings of the engine
so I trusted the shop was doing the right thing.
Thanks for any input. Any suggestions on replacement options and
where to go?
Don
I need to ask what you all think of this sequence of events.
Had a valve spring break on the Z. All springs were replaced.
Then broke another spring within a week. That spring was replaced.
Then the engine blew. 7 and 8 clyinders.... two windows in the block.
The shop says it happens. Really?? After all these new springs?
Would anyone have looked a little closer after the second spring
breakage? I don't know much about internal workings of the engine
so I trusted the shop was doing the right thing.
Thanks for any input. Any suggestions on replacement options and
where to go?
Don
Drifting
Joined: Jul 2002
Posts: 1,484
Likes: 0
From: Morgan Hill Ca.
Whew, were to go? Was this a stock engine?
Busting valve springs and then the engine? sounds like something else could have been going on there? How was the oil pressure and temprature? What cyl.(s) were the springs replaced on? How did the engine blow exactly? Were you getting on it? Sounds like you might have seized something. Windows in the Block? Where in the block?
Busting valve springs and then the engine? sounds like something else could have been going on there? How was the oil pressure and temprature? What cyl.(s) were the springs replaced on? How did the engine blow exactly? Were you getting on it? Sounds like you might have seized something. Windows in the Block? Where in the block?
Thread Starter
3rd Gear
Joined: Feb 2010
Posts: 3
Likes: 0
From: Quakertown PA
Blown engine
Whew, were to go? Was this a stock engine? Stock except for air box, headers, and tune.
Busting valve springs and then the engine? sounds like something else could have been going on there? How was the oil pressure and temprature? Temps and oil pressure were fine. What cyl.(s) were the springs replaced on? Not sure what springs broke, they were vague when asked. How did the engine blow exactly? Accelerating in 3rd gear at about 60mph Were you getting on it? It's a Z06 it should take acceleration at that speed. Sounds like you might have seized something. Windows in the Block? Where in the block?One hole above the oil filter. One hole by the starter.
Busting valve springs and then the engine? sounds like something else could have been going on there? How was the oil pressure and temprature? Temps and oil pressure were fine. What cyl.(s) were the springs replaced on? Not sure what springs broke, they were vague when asked. How did the engine blow exactly? Accelerating in 3rd gear at about 60mph Were you getting on it? It's a Z06 it should take acceleration at that speed. Sounds like you might have seized something. Windows in the Block? Where in the block?One hole above the oil filter. One hole by the starter.
Thanks,
Don
Drifting
Joined: Jul 2002
Posts: 1,484
Likes: 0
From: Morgan Hill Ca.
Would really help if you knew which springs in relation to cyls dropped.
Temps are normal as is oil pressure. soo not caused by them.
Absolutely at 60mph that car will handle what ever you can throw at it even WOT. BUT there is a difference in engine loads from idle to cruise to reasonable throttle transition to WOT.
I would say you lost a rod or two, the question is why?
May have dropped a valve first?? Tear down is the only way to know for sure.
All options are available from replacing the short block with new oil and water pumps, lowest cost to OMG speed and cost.
Temps are normal as is oil pressure. soo not caused by them.
Absolutely at 60mph that car will handle what ever you can throw at it even WOT. BUT there is a difference in engine loads from idle to cruise to reasonable throttle transition to WOT.
I would say you lost a rod or two, the question is why?
May have dropped a valve first?? Tear down is the only way to know for sure.
All options are available from replacing the short block with new oil and water pumps, lowest cost to OMG speed and cost.
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Sorry to hear what happened. Your engine was not the first to blow with holes where you describe. But have a few more questions:
What year?
when did you last change the oil?
What were you doing 10 min before the engine blew? any high speed left hand sweeping corners?
when you changed the springs, did you change the push rods?
if you did change rods, what size where they?
What year?
when did you last change the oil?
What were you doing 10 min before the engine blew? any high speed left hand sweeping corners?
when you changed the springs, did you change the push rods?
if you did change rods, what size where they?
Race Director
Joined: Aug 2004
Posts: 14,639
Likes: 39
From: Winston-Salem North Carolina
St. Jude Donor '08-'09
What does the timing chain look like? There have been quite a few reported on here failing, and I'm sure there have been some that haven't been reported. Do a search on broken timing chains.
seems theres some "flex" in the chain on thses engines, GM tried to address the problem on the LS7's and LS3's with a sort of chain dampner.
My first engine blew going in a straight line, but two days prior I ran Pocono open track(6hrs, high banking long sweeping turns, possible damage done from oil starvation there)
seems theres some "flex" in the chain on thses engines, GM tried to address the problem on the LS7's and LS3's with a sort of chain dampner.My first engine blew going in a straight line, but two days prior I ran Pocono open track(6hrs, high banking long sweeping turns, possible damage done from oil starvation there)
Last edited by GeorgeZNJ; Feb 18, 2010 at 07:48 AM.
Thread Starter
3rd Gear
Joined: Feb 2010
Posts: 3
Likes: 0
From: Quakertown PA
blown engine
It's an 03 with about 14,000 miles. No High G left handers. Stock engine. No cam. Rods were not changed, just springs to Manley's I think. Oil was 1 week old and levels were fine. Timing chain was not broken.
I guess my question is: after the second broken spring, would that have prompted any of you to tear down and look for the cause or would you just go run it a see what happens?
Thanks
I guess my question is: after the second broken spring, would that have prompted any of you to tear down and look for the cause or would you just go run it a see what happens?
Thanks
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Burning Brakes
Joined: Apr 2009
Posts: 946
Likes: 2
After the second spring broke, I would have torn into it. Or at least assured myself you were bouncing it off the rev limiter previous to breaking the springs. If you were not, then I'd want to know why you were breaking 14k mile springs with a stock cam.
My big question is, did it drop valves while creating the windows in the block? I bet it did.
My big question is, did it drop valves while creating the windows in the block? I bet it did.
