Thread: water in oil, head is the culprit!

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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?

sounds like they cut in the water jacket heads are junk you can seal the heads. thats why i use a smaller EX seat id so this will not happen seal them if you want but there junk

no they pour it in the head put psi in the head will push it in the cracks or holes then bake it will work fine on a head that has smalls cracks that have been pined or pours in casting or welded with small leaks but on the ex seat side on a boat i do not think i would use it .if it opens up you will be looking for a new bottom end to

yes using it to seal a bad seat there junk

Problem is, the heads were ported/ polished and had larger valves installed. Then I had them flowed and based upon that #, had a custom cam ground. Now, if I change heads, and don't get the exact flow.... Should have left well enough alone. But I read that using unleaded gas you're supposed to have hardened exhaust seats installed. I tried to do it right, but ended up ruining a set of heads.

The work was guarenteed, that's why the shop is going to fix/repair them. However, I'll have to ask them how long they'll warranty the work once the repaired head is in and back in the boat running high revs. This is a supercharged engine running ~max rpms of 5,500 or so. I definitely don't want salt water in my engine, luckily I was only running it in a lake for break in and hence only got fresh water in the engine.

well i see it is not all the machine shops problem they did what you wanted it just did not work.i would of still did them my way and tell you what you can cut in water so this would not happen with smaller seat od or less chance. sounds like to me they were over ported by some that did not know much there not much iron in the bowl on the stock head i do not go nuts in the bowl get very thin when cut out for 1.880 valves . they may pour sealer in the head but it will not make a better head so if there is no iron were it needs to be sealer is not going to stay. like to see were they are leaking but not seeing them i just would not use them you will blow the bottom end up if they come loose .you will not see much i think with your cam if the heads are not use do your self some big problems buy a iron head like darts or merlins .i would not use your head in on a boat

Okay, thanks. You guys talked me into not using these heads. Pat, you have any good heads for sale?

i may have to see what i have.i will know by the end of next week. i may have some good heads comming up for sale

Okay, let me know. I'll pm you with my email in case I don't check this site. I think off hand my heads flowed around 290 cfm at .600 lift. I would like to get a set that flow comparable #'s

Originally Posted by pat mccarthy

i may have to see what i have.i will know by the end of next week. i may have some good heads comming up for sale