I just had a 355 done to my 1995 LT-1. It was rebuilt about 2 months ago and had some metal go through the motor. So it took out my crank and scored a cylinder wall. My machine shop tore the motor apart and couldn't see anything wrong with the build. But thats old news. Today while scecking for oil pressure before starting it up, my dad said stop turning it over as water was flowing out onto the ground. Couldn't tell exactly where it was coming from. So I cranked it over some more and water was coming from the #8 spark plug hole. I drained the water from the radiator and pulled the knock sensor to get the rest out. Now I am going to pull the passenger side head. Does anyone have any ideas on why/how this would happen? Thanks for any advice.

Fuming mad:

ZMAN Z28

 

I had water come out a header bolt hole and i had it king certed but never a plug hole are you sure? cause plug hole sounds like a cracked head

 

Blown gasket,cracked block or head.

 

Why do these types of things always happen on the passenger side. I'm positive it isn't the block. It is a slim chance it is a cracked head, but I don't see how? The isn't any water in the oil. I used teflon paste on the head bolts. The heads went on the dowel pins very smoothe. I'll find out tomorrow if its a head gasket.

Thanks:

ZMAN

 

Let us know. If it's got a good ring seal it will have very little in the oil. I would crack the plug and take it almost all the way out and if there is water it will come out first if it hadn't been run. Ya have to hold it and unscrew it till oil comes out,but if there is water it will come out first.Just hold the plug in(not to let it all out) till the water stops and oil appears.

 

Well, I took the head off today, there was water in #6 and 8 cylinders. There are a couple of water spots on the cylinder walls. You can't physically feel anything. It is a little discoloration from the water/coolant.

The head gasket looked like it sealed properly, there weren't any signs of any deformities or knicks in the gasket. The machine shop agreed with me also.

They are going to pressure test the heads tomorrow and I'll update.

It just doesn't make any sense, as the block and heads were fine before the rebuild. The motor hasn't run as stated before.

Thanks:

ZMAN

 

Get some oil on the cyl walls.
They might be leaking around the seat's or port's.

 

I took some moly lube and put a light coat on the cylinder walls. #2 is at the top, so I only oiled 4,6,8 walls.

I'll update after the machine shop checks the heads

Thanks:

ZMAN

 

Motor oil would be better and turn it to get the others. Anti Freeze will ruin the walls and rings.

 

Earlier today, I turned it over a little at a time and wiped all of the cylinders out.

Thanks:

ZMAN

 

OK--- sounds like ya are all over it.

 

Nope, don't get me wrong. I appreciate and welcome the adivce. I'm just extremely frustrated. This is the 2nd rebuild since June on this motor.

I had the head pressure checked today. There are no cracks in my head. I brought the head gasket back for further inspection. There is nothing obvious. The only thing the machinist could find was maybee the gasket was compressed a little more on the #8 cylinder. But still no tell all signs of a messed up gasket. The gasket in question is a Fel-Pro, and I know they make quality gaskets. But the last gaskets were GM gaskets, and I ordered another GM head gasket which will be here thursday. So I am probably going to put the head back on and turn it over with the starter only to check for leaks. The head was milled 2thousandths today also, so I know it is true. I took a straight edge to the block today and it looks fine. It's probably not an acurate way to check, but I aint pulling the motor again unless I have to, then it won't be till spring.

So if you have any other suggestions, no matter how obvious they might seem, I won't mind. Sometimes its easy to overlook the obvious.

Thanks so far and I keep any interested updated:

ZMAN

 

Cracked block and they crack around the bore not up and down. Look in the top 1/2" of the bore. It will probably look like a line or a light scratch. If it's bored over .030 it could be.Take a strong light and look real close,ya may not be able to hook your fingernail on it.Ya might try a propane bottle and pass it fast moving around the bore and don't let it stop anywhere.Just do the very tip of the flame so mostly hot air touches the metal. Just heat it to warm to the touch so if ya touch it ya can tell its warm. Do this only if ya find a spot ya are not sure is a crack but do it all the way around the bore so it can expand.

If the heads are OK there is no other place it can come from on an LT1. You and your machinest said the gasket looked good,ya had thread sealer on the bolts,it HAS to be the block.

 

If the head is okay and the gasket is too my next guess would be the block. I would get some dye penetrant and check for cracks in the bore. put the piston in its lowest spot, use cleaner on the bore, then penetrant, followed by developer. Any cracks will show right up.