I know is to be pretty straight forward but I seem to be having an issue with keeping gaskets sealed. I have used felpro 1003 on all builds over the years without issue.

A slow weekend bracket car, 357 running 10.5 - 1 CR. Broke a valve and had to replace pistons/heads. I tried iron 50cc and aluminum 64cc. In both attempts, I ended up with water in combustion chambers. Both times, it looked like fire ring was sealing fine by impression. but the fire ring had a plastic coating that seemed to be spotty at best. The deck and head surface seems straight, with some pitting around water passages clear and solid at chamber sealing surfaces. Is this clear coating something new? I do retorque after fist warm up. I also checked all surfaces with straight edge and see no light.

I was out of 1003 gaskets when changing. Bought some new ones, packaging different than before and a clear coating on gasket? We used to use copper coat on all head gaskets in early days on used parts. Do we need to go back to that.

Any help or advice would be appreciated. Has anyone seen issues like this?

I would pressure test the block. I have never had a 1003 gasket leak. I did however have 2 consecutive stock blocks leak through a cylinder wall before I bought an aftermarket block. One last November then the next in March.

I attribute this to me starting to run a 160° thermostat and building more pressure. Bought a borescope, put 30# of pressure on the block water jacket and there is was.

That what my initial thought was. 2 different head /gasket combos. sticking point was nothing apparent on gaskets other than the clear stuff. some erosion around water area, no trail on sealing surfaces.

I did have a pinhole in last block back in 2011.

I know they are very expensive but in the long run you will be far better off buying an aftermarket block. They are manufactured to serve as a race item not as a rebuild for your "Grocery Getter". I've been through the "Stock Block" thing and wasted a lot of money, not to mention the aggravation and time.

Bob

I guess I should have added that I also attribute it to 55-60 year old blocks. LOL

Thanks guys, I made up plates to allow pressure test. Mr Reed, great idea. I tested with piston out and head on at 30 psi. A pinhole is midway down wall. I will strip parts out, aĺl good stuff. Will be installed in extra block after I pressure test it.

This block started life for me in 2011, replaced a block that had started service in 2003. Old stuff still works though I understand concerns. I have a Dart little M that will be used in full cage Mustang I have.

Thanks again guys.