had my mark IV 454 rebuilt into a forged 496 roller engine. Started it up and noticed slight water in oil. Machine shop at first said the milky substance was the assembly lube they used. I changed oil, and same thing. Plus, I was getting more oil (or whatever it is) out then I put in.

Anyhow, took off intake manifold hoping water seeping past gasket. Nothing found, noticed some rust in the center exhaust cross over (781 heads) and after scrapping gaskets off, took a shop vac to suck out stuff. Noticed the vac was sucking water out of the exhaust cross over. Removed head and noticed water in cylinders 2 & 4.

Took back to shop, they pressure checked and found the hardened exhaust seats (that they installed) leaking on cylinders 2 & 4.

Question is, what now? They said they could flow some type of ceramic coating into the coolant passage ways to fix this leak. Anybody heard of this before?