I killed an LT4
Thread Starter
Instructor
Joined: Oct 2000
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From: Austin, TX
Re: I killed an LT4 (365ZUM)
DEAR GOD!!! I have the same symptoms as you that just started happening a few days ago. There is a pinging noise coming from the engine and is consistent with the RPM's. The check engine light came on for a few days, but is now off. I took the valve cover off last night and it is coming from the #6 rocker arm, or some part from that cylinder. I know that GM had a recall on early LT4 rocker arms back in 1996. Hopefully that's all it is.
[Modified by Charles Klein, 8:44 PM 1/11/2002]
Cruising
Joined: Dec 2001
Posts: 12
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From: Blue Springs MO
Re: I killed an LT4 (Charles Klein)
Geez guys, I always thought the LT1's and LT4's were pretty much bullet proof. I usually baby my 94, but sure hate to think that an occasional trip to the top of the tachometer is going to destroy the engine.
Pat Dolson
94 coupe
Pat Dolson
94 coupe
Burning Brakes
Joined: Aug 2001
Posts: 969
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From: San Diego CA
Cruise-In III Veteran
Re: I killed an LT4 (Charles Klein)
DEAR GOD!!! I have the same symptoms as you that just started happening a few days ago. There is a pinging noise coming from the engine and is consistent with the RPM's. The check engine light came on for a few days, but is now off. I took the valve cover off last night and it is coming from the #6 rocker arm, or some part from that cylinder. I know that GM had a recall on early LT4 rocker arms back in 1996. Hopefully that's all it is.
I doubt it's the same thing, not a pinging but a loud clanging. Even to an untrained ear (like mine) it would sound like a major problem.
I doubt it's the same thing, not a pinging but a loud clanging. Even to an untrained ear (like mine) it would sound like a major problem.
I can't BELIEVE it. I limped it into the shop today, with every check engine light, vibration, and engine knocking/pinging in full affect. The guys at RP Motorsport in Atlanta took it for a drive, and broke the news. I've also spun a bearing (#6!) and my crankshaft is all over the place when turning. I don't know quite how to take it. I had always planned on a 383, but not NOW!!! :(
The only reason they can come up with for my LT4's death is this. The early LT4's had a rocker arm recall back in 1996 that apparently mine never had. The wear and tear over the years caused excessive heat buildup (for alot of miles) and it brought the engine to its knees.
If you have an early LT4, make sure you check this out!!
:(
Instructor
Joined: Sep 2001
Posts: 159
Likes: 21
From: McKinney Tx
Re: I killed an LT4 (365ZUM)
""MTI said I could run my 396 up to 7,000RPM's with no problems. Also put on the Canton 7.5QT Race Oil Pan with the 396. ""
MTI converts them to steel splayed 4 bolt mains.
MTI converts them to steel splayed 4 bolt mains.
Le Mans Master
Joined: Feb 2000
Posts: 7,052
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From: Gladewater Texas
Re: I killed an LT4 (Charles Klein)
Sorry to hear about your engine. But you now can improve the performance and build it how you want it there is good with bad it just depends on how you look at it :)
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Thread Starter
Instructor
Joined: Oct 2000
Posts: 221
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From: Austin, TX
Re: I killed an LT4 (365ZUM)
DEAR GOD!!! I have the same symptoms as you that just started happening a few days ago. There is a pinging noise coming from the engine and is consistent with the RPM's. The check engine light came on for a few days, but is now off. I took the valve cover off last night and it is coming from the #6 rocker arm, or some part from that cylinder. I know that GM had a recall on early LT4 rocker arms back in 1996. Hopefully that's all it is.
I doubt it's the same thing, not a pinging but a loud clanging. Even to an untrained ear (like mine) it would sound like a major problem.
Unfortuneately Charles, I was right.....MY LT4 IS DEAD!!!! :cry :cry :cry :cry
I can't BELIEVE it. I limped it into the shop today, with every check engine light, vibration, and engine knocking/pinging in full affect. The guys at RP Motorsport in Atlanta took it for a drive, and broke the news. I've also spun a bearing (#6!) and my crankshaft is all over the place when turning. I don't know quite how to take it. I had always planned on a 383, but not NOW!!! :(
The only reason they can come up with for my LT4's death is this. The early LT4's had a rocker arm recall back in 1996 that apparently mine never had. The wear and tear over the years caused excessive heat buildup (for alot of miles) and it brought the engine to its knees.
If you have an early LT4, make sure you check this out!!
:(
I doubt it's the same thing, not a pinging but a loud clanging. Even to an untrained ear (like mine) it would sound like a major problem.
Unfortuneately Charles, I was right.....MY LT4 IS DEAD!!!! :cry :cry :cry :cry
I can't BELIEVE it. I limped it into the shop today, with every check engine light, vibration, and engine knocking/pinging in full affect. The guys at RP Motorsport in Atlanta took it for a drive, and broke the news. I've also spun a bearing (#6!) and my crankshaft is all over the place when turning. I don't know quite how to take it. I had always planned on a 383, but not NOW!!! :(
The only reason they can come up with for my LT4's death is this. The early LT4's had a rocker arm recall back in 1996 that apparently mine never had. The wear and tear over the years caused excessive heat buildup (for alot of miles) and it brought the engine to its knees.
If you have an early LT4, make sure you check this out!!
:(
Burning Brakes
Joined: Aug 2001
Posts: 969
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From: San Diego CA
Cruise-In III Veteran
Re: I killed an LT4 (Charles Klein)
That's awful luck, I'm very sorry. It's also an amazing coincidence. Both our engines killed by the #6 bearing within a few days of eachother. Feel free to email me any questions about my rebuild.[/QUOTE]
Thanks for your pity Charles, I'll contact you soon. A 396 huh? WOW!
I think I'll stick with the 383. I've even been thinking about buying a brand new LT4 crate engine, and replacing the cam/heads, and adding all of the other stuff I had on mine. I know John Hutchinson did the same. Just don't know yet though. This whole thing has been a smack in the face to me!
As for the recalls, there is a website that posts all of them, and indicates the production numbers that were affected. I can't remember the website at the moment, but I'll post when I do. CHECK IT OUT!!!
Team Owner
Joined: Mar 2001
Posts: 30,856
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From: Boston, Dallas, Detroit, SoCal, back to Boston MA
Re: I killed an LT4 (AquaMetallic94LT1)
Smokey Yunick found that rotating assy failures that occurred even when rev limits were observed are caused by detonation or ignition crossfiring. The #5 and #7 and #4 and #6 can cross fire if the ignition wires are close together and cause problems. At high rpm you might not notice the cross firing or detonation occurring. He recommended keeping at least 1 inch center to center between the plug wires to prevent the crossfire problem.
We've got an optispark instead of a distributor. ( sounds like that's what he's talking about. )
BTW what were you doing when it happened?
Drag, autocross, road course, stop light race?
The stock pans do have problems on tight turns.
If the pressure drops suddenly when diving into a turn. it can be returned if you get on the gas right away. Sounds backwards but it works.
I'm working on getting an ausump and a road race pan.
Though I still believe the problem in this thread is REV related.
I also know drag racers who take it out of gear at the end of the track
not letting the enging to any braking. That way there's not a sudden reversal of the forces.
Just a thought
Thread Starter
Instructor
Joined: Oct 2000
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From: Austin, TX
Re: I killed an LT4 (BrianCunningham)
I just took off from a stop light. It was two shifts just below rev limit and then the incident. No turning at all. I have 'raced' on ultra-curvy country roads for over 20 minutes hovering at 6000 rpm, without any problem.
One thing I did not mention before was that for a couple of days prior, just when decelerating, the exhaust would emit some popping noises. Since I just had cats removed and headers installled, I assumed that these were normal, but more audible, combustion noises. Could this explain anything?
One thing I did not mention before was that for a couple of days prior, just when decelerating, the exhaust would emit some popping noises. Since I just had cats removed and headers installled, I assumed that these were normal, but more audible, combustion noises. Could this explain anything?
Burning Brakes
Joined: Oct 2000
Posts: 792
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From: Palatine
Re: I killed an LT4 (Charles Klein)
quote:
--------------------------------------------------------------------------------
Smokey Yunick found that rotating assy failures that occurred even when rev limits were observed are caused by detonation or ignition crossfiring. The #5 and #7 and #4 and #6 can cross fire if the ignition wires are close together and cause problems. At high rpm you might not notice the cross firing or detonation occurring. He recommended keeping at least 1 inch center to center between the plug wires to prevent the crossfire problem.
--------------------------------------------------------------------------------
What kind of plug wires were you LT4 guys using? I remember reading about inductive crossfire in the MSD catalog. The MSD's say they prevent this from happening. Not sure if this is BS or not.... Not really related but my friends truck engine blue (96 Dakota 30k miles), and the dealer couldn't figure out why. We later found out his plug wires were really bad in some spots. I dont see how one could keep one inch of space between each wire in a vette??
--------------------------------------------------------------------------------
Smokey Yunick found that rotating assy failures that occurred even when rev limits were observed are caused by detonation or ignition crossfiring. The #5 and #7 and #4 and #6 can cross fire if the ignition wires are close together and cause problems. At high rpm you might not notice the cross firing or detonation occurring. He recommended keeping at least 1 inch center to center between the plug wires to prevent the crossfire problem.
--------------------------------------------------------------------------------
What kind of plug wires were you LT4 guys using? I remember reading about inductive crossfire in the MSD catalog. The MSD's say they prevent this from happening. Not sure if this is BS or not.... Not really related but my friends truck engine blue (96 Dakota 30k miles), and the dealer couldn't figure out why. We later found out his plug wires were really bad in some spots. I dont see how one could keep one inch of space between each wire in a vette??
Team Owner
Joined: Aug 1999
Posts: 69,020
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From: Bagpipes put the "fun" in "funeral"
Re: I killed an LT4 (Charles Klein)
I just took off from a stop light. It was two shifts just below rev limit and then the incident. No turning at all. I have 'raced' on ultra-curvy country roads for over 20 minutes hovering at 6000 rpm, without any problem.
One thing I did not mention before was that for a couple of days prior, just when decelerating, the exhaust would emit some popping noises. Since I just had cats removed and headers installled, I assumed that these were normal, but more audible, combustion noises. Could this explain anything?
One thing I did not mention before was that for a couple of days prior, just when decelerating, the exhaust would emit some popping noises. Since I just had cats removed and headers installled, I assumed that these were normal, but more audible, combustion noises. Could this explain anything?
Unless you were getting some other engine noises that sounded like exhaust pops?
[Modified by Thud, 12:51 PM 1/16/2002]
Team Owner
Joined: Mar 2001
Posts: 30,856
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From: Boston, Dallas, Detroit, SoCal, back to Boston MA
Re: I killed an LT4 (Charles Klein)
The popping is normal, actually that's what I like about my muffler eliminators :D
The LT4 is an OBDII engine, so unlike the LT1 there's a sensor after the cats.
If that cats are gutted, then it needs to be "faked out" or a code will trip.
Were you getting any codes?
The LT4 is an OBDII engine, so unlike the LT1 there's a sensor after the cats.
If that cats are gutted, then it needs to be "faked out" or a code will trip.
Were you getting any codes?
Thread Starter
Instructor
Joined: Oct 2000
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From: Austin, TX
Re: I killed an LT4 (BrianCunningham)
I don't think so. Rottie sent me instructions on pulling codes, using a jumper. According to the procedure, as I understood it, there were no codes.
Drifting
Joined: Aug 2000
Posts: 1,614
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From: Colleyville Texas
Re: I killed an LT4 (BrianCunningham)
[Quote] I also know drag racers who take it out of gear at the end of the track not letting the enging to any braking. That way there's not a sudden reversal of the forces.
Real good point. My problem happened at a 1/8 mile track, with a very short run off at the end of the track, when I let off at 6400 RPM's and started braking. Will keep this in mind.
Real good point. My problem happened at a 1/8 mile track, with a very short run off at the end of the track, when I let off at 6400 RPM's and started braking. Will keep this in mind.
Thread Starter
Instructor
Joined: Oct 2000
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From: Austin, TX
Re: I killed an LT4 (Red Rocket)
An update:
A main bearing spun first. Then another main bearing and rod bearings. The only reasonable explanation seems to be oil starvation.
Chris at Speed Demon found that all three bolts on my oil pump were loose. This would explain the loss of oil to the crank. First, I want to confirm with Austin Corvette, who looked at it first, that they did not touch the oil pump. I already talked to them a lot, and I am almost certain that they did not. If the failure was due to loose bolts on the oil pump, this is good news for other LT4 owners. It's something that can be checked or corrected.
Here are a few photos of the crank:
[Modified by Charles Klein, 6:51 PM 2/3/2002]
A main bearing spun first. Then another main bearing and rod bearings. The only reasonable explanation seems to be oil starvation.
Chris at Speed Demon found that all three bolts on my oil pump were loose. This would explain the loss of oil to the crank. First, I want to confirm with Austin Corvette, who looked at it first, that they did not touch the oil pump. I already talked to them a lot, and I am almost certain that they did not. If the failure was due to loose bolts on the oil pump, this is good news for other LT4 owners. It's something that can be checked or corrected.
Here are a few photos of the crank:
[Modified by Charles Klein, 6:51 PM 2/3/2002]