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I was installing the cylinder head bolts (New Bolts & Gasket) on my 2003 LM7 last night and I heard a slight hissing noise. I found some liquid coming out of the block near cylinder head #2. I've never seen anything like it... here are some pictures. I just need to know if I should do anything thing about it. (I did some searching and didn't find anything about this area on the block and not it's not a freeze plug!)
If fluid is coming out of the block then there has to be a crack in the block.
What's the history of this engine?
Andrew
This engine has 71,000 Miles on it. Came out of a 2003 1500 Avalanche always had GM dealerships work on the vehicle. When I was torqing down the head bolts is when I first saw this. The engine ran great in the avalanche before I pulled it out the block was done dry on the outside. I've heard about ls blocks being porous but haven't seen this before...
This engine has 71,000 Miles on it. Came out of a 2003 1500 Avalanche always had GM dealerships work on the vehicle. When I was torqing down the head bolts is when I first saw this. The engine ran great in the avalanche before I pulled it out the block was done dry on the outside. I've heard about ls blocks being porous but haven't seen this before...
Nope, just hit in the back damaged bumper and some cladding. Owner took the insurance money and walked away from it.
I guess if it was me, I would put the heads on and do a pressure test on the coolant system in the block. The system should hold 20psi without any leaks.
I guess if it was me, I would put the heads on and do a pressure test on the coolant system in the block. The system should hold 20psi without any leaks.
Andrew
Heads & New Gasket are installed, I'll be able to do the pressure test once I get the pump back on and the cooling system hooked up.
If anyone else is reading this... have you seen this before, if so what did you do?
The head bolt holes are blind .if you do not clean and dry thoroughly , you can crack the block. Did you use a thread chaser and clean out old loctite? Did you make sure there was no coolant in holes prior to installing heads? These steps are very important
The head bolt holes are blind .if you do not clean and dry thoroughly , you can crack the block. Did you use a thread chaser and clean out old loctite? Did you make sure there was no coolant in holes prior to installing heads? These steps are very important
I read a long time ago that the head bolts are not blind, but go into the water passages...Is that wrong?
They do on a sm block chevy , but not on an ls. I researched it when I put my ly6 together.
The block was upside down for a few hours (installing new oil pan), so when I rotated it back to it's normal spot - coolant didn't completely drain out of the holes (The only way coolant got in there when I lifted the heads off, that's the only thing I can think of). So my question is even though this happened... should it harm anything if nothing passes passes though this area?
Sounds like you may have cracked the block from coolant in the bolt hole and installing the head bolts. "You ask should it harm anything if nothing passes through this area?" It appears you may have cracked the block and the crack runs through a water jacket. I think you already have that bad gut feeling that is probably what happened. Why were you changing head gaskets and bolts on a 71k mile engine? I've seen it plenty of times. People try to do preventive and unnecessary maintenance on engines and only end up making it worse than it needed to be. Good Luck hopefully I'm wrong!
The engine is going to run on an engine stand before it enters the engine bay. I'm gonna try some JB weld and go from there but I won't know anything for a few months. Thanks for the tips!
The head bolt holes have to be cleaned out since they are blind. I would say there was fluid in there when you tightened the bolts. I think you will have to take it apart and see how bad the crack is. Hopefully i am wrong but i think your block may be shot.
12-09-2015, 10:34 AM
Leak near cylinder #2 - LM7 Block ?? 
