Please help! Terrible engine knock at 30k

[acammer]

Yep, sounds like a bearing to me. Painful sounding. Stop running it and get it to an engine builder (not the dealer) and have it repaired. I agree with these guys, a clutch at 19k is insane - I suspect major abuse in it's previous owners hands. That being the case, I'd have your engine builder go over the whole car really carefully, fresh fluids in the gearbox and rear end, etc.

[R3VOLT]

So in everyone's opinion weather be it spun bearing, bearing knock, piston slap or wrist pin, is this something that can be fixed even if I have to completely strip and pull the block to take it to machine shop? I mean it's obviously not seized. I have several mechanics that will help and machine shop friends plus I have done a complete rebuild albeit a different monster (78 Camaro Chevy 350) before myself. The last time I ran it was when took the video. I put gunk to clean the parts and have since put on jack stands and drained the oil. Sounds like best bet might be a complete rebuild along with checking out everything else. I would be pulling the exhaust and headers to replace them anyway. Fresh fluids everywhere and this way I know it was done and done correctly. That's a lot of piece of mind.

[acammer]

Originally Posted by R3VOLT

So in everyone's opinion weather be it spun bearing, bearing knock, piston slap or wrist pin, is this something that can be fixed even if I have to completely strip and pull the block to take it to machine shop? I mean it's obviously not seized. I have several mechanics that will help and machine shop friends plus I have done a complete rebuild albeit a different monster (78 Camaro Chevy 350) before myself. The last time I ran it was when took the video. I put gunk to clean the parts and have since put on jack stands and drained the oil. Sounds like best bet might be a complete rebuild along with checking out everything else. I would be pulling the exhaust and headers to replace them anyway. Fresh fluids everywhere and this way I know it was done and done correctly. That's a lot of piece of mind.

Should be fixable. IF it just started you might have a reasonably easy fix, or things might be a little more expensive - but it's not completely trashed by any means. Cost may be the determining factor on fixing vs. replacing, a good shop should be looking out for that for you. You won't know till you get into the motor - get the pan and the rod bolts off/out and you'll have a much better idea.

[arkentect]

It doesn't sound like a spun bearing, def more rod knock, but the spun bearing could be the culprit. At least not from my personal experience. I had my 5/2010 LLT spin the #4 bearing last year about 2 months before the warranty ran out. It started as a slight ticking sound that I could only hear while siting in the car and it only happened under load acceleration from 1800-2000 rpm. A spun bearing won't present that loud overnight, the car has probably been ticking for a while without you noticing which means the loud knocking noise you're hearing is rod knock. If I were you, I would pull the oil pan yourself check the pan and the oil for a metallic sheen and cut the oil filter open to check for metal. Until then, I bid you goodluck, I had my motor replaced with a new crate motor in hopes that I won't have this issues ever again but its always in the back of my mind.

[R3VOLT]

Thanks that will be the next step later today or tomorrow is pull the oil pan and remove the throttle body & intake manifold since I will be porting those regardless. I will keep everyone posted and insert picture when I get inside. Much appreciated!

[R3VOLT]

I'm putting headers and exhaust on anyway so I might as well take those off and get them out of the way too!

[arkentect]

Originally Posted by R3VOLT

Thanks that will be the next step later today or tomorrow is pull the oil pan and remove the throttle body & intake manifold since I will be porting those regardless. I will keep everyone posted and insert picture when I get inside. Much appreciated!

If it is a bottom end issue.. which I'm 95% sure it is, it might not be cheaper but it will be better to just buy a new motor for the car. With much piston slap there's bound to be damage that would cost quite a bit to fix

[Leo72793]

Im going with bearing. my old 98 made the SAME noise and it was toast. Bearings sound like that when they are bad.

[booneSS13]

Mine made this kind of noise and it ended up being failed ringlands on 3 pistons. It could be many different things though so I'd say the best thing to do is troubleshoot as much as you can with the engine intact in the car.

It may be worth while to pay a shop a couple hundred to figure it out so at least you're not chasing your tail like I did when my engine failed. I've seen something as simple as clogged catylic converters make this noise, so you never know. See if someone or a shop will use a borescope on it too.

Anything is fixable with enough money. The question is what's your budget? worst case scenario is a cracked block which I highly doubt or cylinder wall damage which is a possibility. In the case of cylinder wall damage it would have to be re-sleeved or you could just start over with a fresh block. If rod bearings is the issue, a tear down and rebuild is what's needed and it would be safe to just have a machine shop hone and clean up the block.

[RichSS2006]

Agree with spun bearing/piston slap. I recently helped a fellow member change out an LLT for a new crate motor. Really not many people rebuilding these engines so not many aftermarket replacement parts or rebuild kits. GM did give him money back for the core when it was returned.
The removal and replacement is pretty straight forward. Remove hood and hoist it out after removing exhaust, transmission etc.
Talk to your Chevrolet parts guy. They do give discounts to DIYers. Good Luck, Rich

[R3VOLT]

So when you swapped motors, did you get another LLT or was it an LFX? What I'm hearing from a certified Chevy dealer guy is the LLT was known for this problem due to the screen clog under the cam actuator which in turn does not allow the oil to pass thru ultimately leading to the problems with the spun bearing, rod knock and piston slap. The LLT sounds like a ticking time bomb that should be a class action lawsuit. Apparently Chevy is/was very aware of this hence the new design in 2012-15 motors.

[Full Lock]

sounds like it's in the valve train. pull the valve covers and see what you can find.
sucks man GL.

[RichSS2006]

Originally Posted by R3VOLT

So when you swapped motors, did you get another LLT or was it an LFX? What I'm hearing from a certified Chevy dealer guy is the LLT was known for this problem due to the screen clog under the cam actuator which in turn does not allow the oil to pass thru ultimately leading to the problems with the spun bearing, rod knock and piston slap. The LLT sounds like a ticking time bomb that should be a class action lawsuit. Apparently Chevy is/was very aware of this hence the new design in 2012-15 motors.

It was a 2014 and up version of the LLT. The LFX has integrated exhaust manifolds. I also think the computers were different between the LLT and LFX, so no go on that swap. The new LLT had upgrades on it. So I suppose some of the previous ills were fixed. I know the PCV system was a little different as were the fuel injectors. We used the old injectors, but the crate engine had a different seal kit to marry them up to the new LLT heads. The install was pretty straight forward. The new motor also came with a 24 month warranty which was a plus.

[tlavoie87]

i dont get why so many llt have issues im going on 95K with zero issues with the motor and its blown.. MAINTENANCE, MAINTENANCE , MAINTENANCE take care of it it takes care of you ..tons of people knocking the llt