BAD internal noise after start up. Expert help needed!
Engine missing and running on 3cyls. Expert help needed! Hey guys,
My LS1 has a serious problem and I need your help! Let me know if this should be posted in a different section.
After a casual drive to work below 3000rpm I parked my car for the day. I went out after work and as soon as the engine started it was only running on two or three cylinders! I hooked up a scanner and there are no bad codes that would indicate the car is hardly running. The gauge was showing good oil pressure so I tried to run the car for about a minute but it didn't get any better so I just left it parked
What could have happened on start up to cause this? Can the timing chain ever skip a few teeth? Is there a cam or crank sensor that could cause all the timing to go way out of sync? Can the PCM program get messed up and require a reflash?
The engine is a freshly built (2k miles) 347 with forged pistons, AFR 205s, Comp lifters, Rollmaster dual chain, GMPP chain guide, high flow oil pump and all the other usual goodies. Every part was brand new and assembled to spec.
Any help would be appreciated
My LS1 has a serious problem and I need your help! Let me know if this should be posted in a different section.
After a casual drive to work below 3000rpm I parked my car for the day. I went out after work and as soon as the engine started it was only running on two or three cylinders! I hooked up a scanner and there are no bad codes that would indicate the car is hardly running. The gauge was showing good oil pressure so I tried to run the car for about a minute but it didn't get any better so I just left it parked
What could have happened on start up to cause this? Can the timing chain ever skip a few teeth? Is there a cam or crank sensor that could cause all the timing to go way out of sync? Can the PCM program get messed up and require a reflash?
The engine is a freshly built (2k miles) 347 with forged pistons, AFR 205s, Comp lifters, Rollmaster dual chain, GMPP chain guide, high flow oil pump and all the other usual goodies. Every part was brand new and assembled to spec.
Any help would be appreciated
Last edited by V8er; May 4, 2007 at 04:10 PM. Reason: 1
check the oil... make sure you dont have a bad head gasketleak that has caused a hydroloc type of situation (less severe obviously because yours is still running). The reason I say that is you have a new shortblock but was the block decked and stuff? Im sure theres a million things it COULD be.
Only well to tell is to tear it down.
Mine made a similiar noise when I broke the roller off one of the lifters. Had good oil pressure.
I stopped to go to the bathroom on the side of the road. Got back in then bang. I thought a farmer or somebody shot the car. It was when I started it back up.
I like the starter suggestion and hope like hell that's all it is.
I like the starter suggestion and hope like hell that's all it is.
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Originally Posted by AintQik
I stopped to go to the bathroom on the side of the road. Got back in then bang. I thought a farmer or somebody shot the car. It was when I started it back up.
I like the starter suggestion and hope like hell that's all it is.
I like the starter suggestion and hope like hell that's all it is.
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Teching In
Joined: Jan 2006
Posts: 19
Likes: 0
Originally Posted by 5.3LJimmy
Starter not disengaging from the flywheel? It's odd that you drove to work w/ no problems and as soon as it cranked up it was making noise. Could be a bad starter.
)jeremy
Originally Posted by j-dubya
x2. check out your starter for starters ( no pun intended )
)It is looking more and more like the heads need to come off unless someone can think of another good reason why it would be mising this badly?
Last edited by V8er; May 4, 2007 at 04:05 PM. Reason: 2
Originally Posted by Asmodeus
with such low miles on it it could just be a part failure.. no real explanation other than it just failed.
If a lifter broke would it have damaged any other part(s) of the engine or should I be able to replace the lifters and go?
Has anyone ever heard of a timing chain skipping a few teeth and causing this kind of problem? The reason I ask is because it really feels like the engine is running on about 3 cylinders, not something I would expect to hear and feel if one of the lifters broke!
Last edited by V8er; May 4, 2007 at 04:06 PM. Reason: 1
Originally Posted by Grimes
I have never ever heard of a timing chain skipping teeth. Only breaking. Skipping teeth and staying on would be almost impossible.
Banned
Joined: Apr 2006
Posts: 1,875
Likes: 1
From: Naperville, IL
I''d take it to a shop. One of the sponsors here if you are close enough and have them give you their opinion. It's very hard to diagnose something like that without seeing the car. And a morning bump for you.
and yes, I have heard of a chain jumping before, and if it did, you could have valves hitting pistons.
and yes, I have heard of a chain jumping before, and if it did, you could have valves hitting pistons.
Sorry to hear about your troubles. I would suggest one of four things and in order of its easiness to check. Broken rocker, broken pushrod, broken or spun around lifter, broken or loosened rod bolt. Take off the valve covers and check the rockers and pushrods. No dice, remove the heads and check the lifters. If a lifter has broken or spun around, it will make constant bad noises as it begins to desinigrate your cam lobe. Last, you'll have to pull the motor and check rod bolts. You cannot ignore it for sure. If it is a knocking sound like you describe, something in the valvetrain or bottom end has severely broken and you'll destroy the entire engine if you keep running it. I hope this helps. Hell, I feel so bad for you that if you were near North Carolina, I'd check it for you myself...
I didnt have this problem on an LS1, but on my 502, the symptoms are similar, I did exactly what you did, park it, then come back. On mine, a bolt on the rocker arm got loose and the pushrod actually managed to slip off to the side, luckily no damage. If you can, pull the valve covers and double check those, its a simple thing to check for.
One other thing it might be, because it happened on my safari van, was a cam sensor that was messed up and not reading right, so it threw everything outta sync. That would explain why you needed to stay on the throttle to keep it running.
Thats just my suggestion tho, keep us posted to see what the real problem was.
One other thing it might be, because it happened on my safari van, was a cam sensor that was messed up and not reading right, so it threw everything outta sync. That would explain why you needed to stay on the throttle to keep it running.
Thats just my suggestion tho, keep us posted to see what the real problem was.
TECH Regular
Joined: Jan 2002
Posts: 434
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From: Bellville, Texas
Okay this is going to sound crazy... but... I'm going to post it anyway. I had my LS1 rebuilt with forged pistons, big cam, 243 heads, etc. etc... after I hydrolocked it. 2 days into driving it again one of my 02 sensors went bad and it sounded like all hell broke loose in the engine. I couldn't keep it idling unless I was feathering the gas. I thought I was about to throw a rod as bad as it sounded. I, in no way, thought it could have been an 02 sensor. I was sure something came loose or broke in the motor. I did some research and posted like you and somebody wrote just about the same thing I am writing now and low and behold that was the problem. I REALLY hope it is yours as well. Good luck and keep us posted.