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Diagnose this sound. #)$*#()$#

Chunkee

Chunkee

Lifer
http://picasaweb.google.com/lh/photo/30JWpRNDAnsmlLqG9yxaog?feat=directlink

Since I am not getting any assistance at LS1tech or FullSizeChevy, I will give you guys a whirl.

2005 silverado (just bought) got screwed without lube.. other than the knock, i have coolant/oil mixture getting into intake manifold, rough idle. No smoke, no misfire. Losing coolant with no signs outside. No oil on dipstick.

I have had the intake manifold gasket replaced, cleaned MAF, Lucas Oil coinditioner (quieted it a bit) and PCV tube system cleaned.

Knock is loudest at cold, and at warm idle, much quieter at RPMS higher than idle. More than likely I have the notorious Castech head porosity leak problem that the fuckheads at GM are aware of, but will not do anything about it. I did not make one payment on this truck and things started to begin with noise after oil change. My dad thinks dealership overfilled it to keep it quiet.

So, do you think that knock is deep like a wrist pin or bearing? Should I just replace the heads? Go with new engine, or smash it into the dealership catching it ablaze and let them all burn with the truck..lol?

My first truck and look what happens.

What do you say doctors?
 
i drove it around, looked at dip stick, sounded fine etc. other than the engine, it looks brand new, one owner, 65000 miles. one would think..but clearly was fucking wrong..move that aside...fix engine or replace it?
 
I'm not clear on this, you drove it without oil?

Also, a car sounding fine 'other than the engine' is not fine at all.
 
I don't truly know as I'm far from well versed in the LS1 engine. The vid with the audio is great, but without being in front of it, it's hard to tell exactly.

Before condemning the engine, I'd pull the valve covers off and investigate possible collapsed lifters. It sounds like that or rod bearings to me. Wrist pin failures are virtually non-existent in my experience. I think it's lifters or lifter related because of the symptoms you describe. Once the RPM's come up the oil pressure does also and helps pump up the lifters.

I don't think you'd be able to have the engine rebuilt for the price of a replacement motor but I may be wrong. It would obviously be different if you could do the work yourself.

My $.02. Take it with a grain of salt.

My understanding is that the LS1 is a zero lash engine (could be wrong though) so there should be no adjustment available on the rocker arms. If there is any free play, that would confirm my diagnosis. You will need to bump the motor over to check all the valves as you you'll want to check them when the valve is closed.

Sorry to be so wishy-washy with the answers, but I pretty much quit working on cars over a decade ago.

See if this sounds similar. http://www.youtube.com/watch?v=LSOzH2m62aA
 
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boomerang has good advice.

if the knock is in the bottom end, it's about 99% certain that it's a rod bearing. mains don't knock and wrist pins are definitely rare. you'd be more likely to see a wrist pin problem as an assembly issue, with failure eminent on the first start, not at 60k. and it doesn't sound like piston slap.

if it's in the valvetrain, it's a doozy; i don't think a collapsed lifter could cause that racket. you may be able to tell where the noise is loudest with a stethoscope, though that's far from foolproof. try holding it on the oil pan as opposed to the cylinder head and see which is louder.

what's this about coolant in the oil? was the intake the cause of this, or is it still not fixed after doing intake gaskets? are you sure the intake is not cracked? also, overfilling the oil would not cure a rod knock or lifter clack unless the part was actually immersed in oil, which would cause other problems (lots of smoking, and with enough overfilling the crank could lug down and you could even basically hydrolock the pistons).

has a compression test been done? if there are no misfires and compression is good, it's probably in the bottom end. valves stuck open or other leaks would show in compression, valves stuck closed should cause a misfire (intake would block fuel, exhaust would cause detonation).

if there has been a lot of coolant in the oil, it's pretty much guaranteed that the bottom end is trashed. when the truck cools down, the emulsion in the oil pan seperates and the water/antifreeze mix will be on the bottom, the first thing to get sucked up the pickup tube the next time the truck is started. water and antifreeze do not lubricate bearings well.
 
You can drop the oil pan to try and get a look at the inside from underneath. That will also let you see what kind of metal goodies are laying in the bottom of it.
 
AdamK47 said:
You can drop the oil pan to try and get a look at the inside from underneath. That will also let you see what kind of metal goodies are laying in the bottom of it.
Click to expand...

that too, if you don't mind just getting right down to business. i think you're gonna find an obviously spun rod bearing.
 
It's too loud for valve-train noise. Lifters usually make a less substantial sound. I'm calling it a spun rod bearing. That's what my dad's Stealth sounded like just before it died.
 
The coolant/oil mixture is still in the intake after the intake gasket was replaced. The noise does not get louder on reving up the engine. It is noisiest on idle. You can barely hear it in the cab...weird situation. I listened to some other vids on youtube, LS1 knock, and mine sounded like one that had bad lifters..? i plan on pulling the valve covers and intake off this Friday when weather gets better. what a pain in the ass. bad thing is, GM knows of the flaw in the heads, and will not do anything about it. no more GM for me.

it seems to sound more like this one as well. his findings were lifters..?

http://www.youtube.com/watch?v=nTDaq1tY7tY&feature=related
 
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You need to do a compression check. It sounds like someone lost a screw or something down the intake manifold and it made its way past the intake valve and into the combustion chamber. Ask me how I know.

IMG_2757-1.jpg

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IMG_2748.jpg
 
Without listening, it sounds like you've gotten some ideas as to where to start looking. Though, the trucks do not have an LS1 engine it is a variant of such. Is it a 5.3L or 6.0L?

If it's the 5.3 variant, in all honesty, those are extremely easy to find low priced and it would likely be easier to yank yours out and just replace it than it would be to troubleshoot it.
 
It is a 5.3, and I have found one in VA, an HO version with 20000 miles on it for 800 bux. He said he would install it with parts for another 500 bux.
 
if you trust that guy, it'll be a hell of a lot cheaper than fixing what you have.

Maybe offer him your engine for a couple hundred dollars.
 
Chunkee said:
It is a 5.3, and I have found one in VA, an HO version with 20000 miles on it for 800 bux. He said he would install it with parts for another 500 bux.
Click to expand...

Try junkyarddog, i've seen them as low as $300 complete and other places offered $1000 for one installed.
 
The 5.3s are pretty notorious for piston slap, but that is one of the worst cases I've heard if it's the case.

I've got close to 130K on mine and it's a wonderful, strong engine.
 
If it's piston slap it usually doesn't increase with revs and will go away after the truck is warmed up.

Do a search for piston slap on google and I believe you will see a lot of people with these trucks have this issue. I don't fortunately. Typically the coolant loss is water pump related too. It seems you got a lemon b/c I haven't heard of these issues with a 5.3 with that low of mileage.

After it's all over, get a tune and remove the torque management. The factory tunes leaves a lot on the table for the LSx variants.
 
joutlaw said:
If it's piston slap it usually doesn't increase with revs and will go away after the truck is warmed up.

Do a search for piston slap on google and I believe you will see a lot of people with these trucks have this issue. I don't fortunately. Typically the coolant loss is water pump related too. It seems you got a lemon b/c I haven't heard of these issues with a 5.3 with that low of mileage.

After it's all over, get a tune and remove the torque management. The factory tunes leaves a lot on the table for the LSx variants.
Click to expand...
that's not the case on my car
 
i don't know about not increasing with rpm, but it should definitely be worse when the truck is cold.
 
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