Leak down test fail

[Boyd12]

"Your head is either pitted from corrosion or the cyl is leaking" That is what I thought. This is the head I am using. When it leaked the first time, I removed it and put a little JB Weld in the pits by the water intake and in other places just in case it was leaking there. It is smooth and straight. Same with the cylinder. This is driving me nuts.

 

[Poormanracing]

You can see the discoloration in the head and the pitting.what does the deck of the cyl look like.it does not take much to leak out.

 

[Boyd12]

The discoloration is from the camera, not the head. I think you are correct, that the pitting is causing it. That being said it doesn't take much pitting at all to cause a problem! I filled in the minor defects with JB Weld and smoothed them out and it still leaks.

 

[Poormanracing]

Get it machines flat.a few thou then find a thicker base gasket to make up for it.can do the same with the top of the cyl

 

[Boyd12]

The head and cylinder have been machined. I put a straight edge on them and they are straight.

 

[Boyd12]

I have been out of town and working a lot but now I have some time to work on it again and it still has the problem. I thought maybe the base gasket was leaking sending pressure up the cylinder studs causing it to leak out of the nuts, but the gasket has no external leaks. I have an aluminum billet head. I installed it, same thing. Four cylinder heads, two cylinders, and three cases. ALL leak.

 

[Poormanracing]

Don't know what you are doing but.you are doing something wrong or you are using the wrong head gasket or base gaskets.you are not by chance ordering a head gasket for a di?by mistake?or a di base gaskets?you don't have the studs for cyl not seated enough and not letting the head bolts seat?

 

[Poormanracing]

I think your head studs are upside down.im not sure of the difference in thread length but I think that center mark needs to go into the case

 

[Boyd12]

Don't know what you are doing but.you are doing something wrong or you are using the wrong head gasket or base gaskets.you are not by chance ordering a head gasket for a di?by mistake?or a di base gaskets?you don't have the studs for cyl not seated enough and not letting the head bolts seat?

“Don't know what you are doing but you are doing something wrong” Agreed.

“or you are using the wrong head gasket or base gaskets” They are correct.

“You are not by chance ordering a head gasket for a di?by mistake?or a di base gaskets?” No, they are for the carbed engine.

“you don't have the studs for cyl not seated enough and not letting the head bolts seat?” The studs are correct. What do yo mean by “letting the head bolts seat”?

 

[Boyd12]

Both cylinders are straight, one has been decked. I have an ADA billet head. It also leaks. The torque wrenches appear to be correct. KMN.

 

[FL-Rider]

You will have to do process of elimination. You could get some 1/8" rubber sheet and make holes in it for the head bolts. I found that a hollow punch from harbor freight works good to make the holes in the rubber. Snug down the head on the rubber sheet and then do the pressure test. If it's still leaking then the problem is likely in the cylinders.
I had a similar leak, and it turned out to be the head. Try using the straight edge across the head from different directions to see if the head is flat from all angles. You could also put the head on a piece of glass to check for flatness. Or, try settting the head on the cylinder with no gasket just to check it.

 

[Boyd12]

Thank you for your input. The head has been milled and the cylinder has been decked. According to the straight edge it is straight. I put the head on the cylinder with no gasket and checked. No gaps. I have no idea why it wont seal

 

[FL-Rider]

Could it be that the machine shop machined the cylinder and/or head at a small slant and took the material off unevenly? Does it leak when you test the cooling system side or when you test the crankcase side?