SB head fix in exhaust cross-over....hmmm....

Guys,

I ran into a problem where there appears to be a crack in the heat cross over passage in my '596 castings. This has already dumped some coolant into my running motor, end result is that just the short-block remains in car as I yanked the heads to get them checked.

These heads have been heavily ported, have barely any run-time on them since re-build, competition 5 angle valve job, new guides, so I'd hate to toss them.

The machine shop pressure tested them, they are suggesting we use epoxy to completely fill the cross-over itself. They claim to have done this type of a fix many times, on different types of heads.

I'm thinking this may work, heck, the cross-over filled epoxy won't be getting much movement at all. Only worry is the epoxy facing the hot exhaust gasses right opposite the regular exhaust port.

Has anyone dones this, seen this type of a fix done? What are the chances of this working? Or am I really just blowing my $$$ ($100 fix cost, not bad considering what I have tied up in these heads and barely any runtime to show for it...LOL).

Need some honest opinions here...give me what you got!!!

Diplomat, on Dad's Pontiac heads, they fill the crossover with molten aluminum. Wonder if this might be safer?
Tom Hand

Filling the heat crossover is an old racer trick, but I believe it's best to use a high quality aluminum to do it after cleaning the passage very well.

A crack in that passage would leak water into the exhaust and tend to be pumped out with it while running. But it could seep in easier if the engine was off and the exhaust valve was off of its seat,filling that cylinder.

Did the machine shop confirm that it is actually "in" the crossover as opposed to a crack in a port from the heavy porting? Have they been magnafluxed to check for cracks in the chamber?

Not sure how it works, but would a warm/hot running engine tend to open a crack more than when its cool?

I've blocked off heat crossover passages in heads with a thin aluminum shim coated with high temp silcone on both sides. Some intake gaskets don't have a hole for the heat crossover, which helps to block it and backs up the aluminum shim. (Scratch that - wrong end blocked. )

Quote:

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Filling the heat crossover is an old racer trick, but I believe it's best to use a high quality aluminum to do it after cleaning the passage very well.
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Did the machine shop confirm that it is actually "in" the crossover as opposed to a crack in a port from the heavy porting? Have they been magnafluxed to check for cracks in the chamber?

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The machine shop pressure tested the heads, they quickly saw the bubbles coming out of the cross over passage. The problem was, they were never able to really peg it down to a specific area, apparently due to the tight space in there. They tried using the bore scope camera as well, no luck.

I was already using the Mr.Gasket UltraSeal intake gaskets with the blocked-off exhaust ports. So the fix they are going to attempt is to sand-blast the port first to roughen up the finish on the material and then completely fill the cross-over in the head and prevent the coolant leak in the first place. I'm somewhat leary of how long term of a fix this is, assuming it works OK to start off with.