Rusty exhaust valves??

[69Bee]

Again, you have an issue where water (coolant) is leaking into the cylinder past the exhaust valve. Another big issue I see is that someone sprayed copper coat onto the gasket which is incorrect. You should NEVER spray copper coat on a Cometic gasket as it will cause sealing problems. The ONLY gasket that will get sprayed is a steel head shim (block side only) or a head gasket with one or both sides metal. You never spray a composite head gasket as it will affect the sealing ability of the gasket. Cometic gaskets are installed dry as the black surfaces are a rubber layer and will not seal properly if not installed dry. This is not the cause of the water intrusion because the evidence shows that it came in thru the exhaust valve. Replace any bad valves, do a complete valve job, surface the heads to the proper Ra finish with a mill using a PCD insert, reinstall with new Cometic head gaskets (install dry, no sealer), and ensure any/all exhaust bolts/studs that go to water have sealer on the threads. I use a Teflon thread sealer by Permatex, and if studs/nuts, I put an anti-seize on the threads for the manifold nuts.

 

[PeteyDaMan]

Heads are dropped off at the machine shop for a valve job, milling and some bowl work.
If there are any cracks in the heads, they'll find them and let me know.
And yes, I'm the dumb *** that sprayed one of the Cometic gaskets with copper. Don't know what I was thinking.

All the exhaust valves are leaking FYI, I tested by flipping the heads over, filling the combustion chamber with water and blowing compressed air into the exhaust port.
It looked like I had dropped an Alka-Seltzer into the head there were so many bubbles.

 

[69Bee]

Ask the shop what they use to surface aluminum heads. If the surface is too rough, you will end up with "Cold" leaks. Head will seal when the engine warms up, but when it is cold, the grooves (rough head surface) provide a path like a canal for coolant to leak out and into the cylinders. I use a Diamond insert (PCD) and slow the feed speed for a fine finish. If they use a rotary broach with carbide, it will be too rough. Even the old Peterson 85B mill had to be converted to handle aluminum heads. I use surface grinders with insert plates attached to the wheel for the PCD and CBN inserts.

 

[turbo t]

Had this issue with a customer's engine. Ended up being when they cut heads to put seats in, they hit water. That was a hard one to figure out.Edelbrocks

 

[dvw]

If it is getting water it has to be minimal. The piston tops and chamber would not have any carbon. A few years ago mine had one plug that would get rusty. Eventually dveloped a hole in the floor of the intake port. Not a crack but a pin hole. Caused it to hydraulic. It was fine one week, hydrauliced when I tried to crank it the next week. Welded it up, and its been good since. As far as copper coat on Cometics. I've reused Cometics with copper coat. 15-1 compression. Never an issue after 100's of passes. The cylinder head and block surfaces are properly finished. The heads (Indy-1) are milled all the way down to 57cc to boot. A full pressure check of the head will tell.
Doug