I'm in the process of tearing down a spare engine, plucked from my old 95Z. Internally, she's looking surprisingly clean, especially for 168k showing on the clock. In any event, I pulled the heads and noticed something I don't recall seeing before. The coolant ports in the heads have a milky greyish-green coating on them, with a consistency similar to wet oil-based paint. Last time I tore an LT1 down, I don't remember seeing this. Is it just remnants of dirty coolant (non-dexcool, of course,) or something else? Ultimately it doesn't matter, since everything will be rebuilt, so I'm only posing the question to satisfy my curiosity.

 

i would say it was mixing with oil

 

Ditto.

 

maybe its aluminum corrosion mixed with the antifreeze. has the engine been sitting for a while?

 

The car it was in sat for about 3 years. I recently sold it as a roller to a friend, who somehow managed to damage the engine before pulling it and giving it back to me. I suspect he revved the **** out of it, because it was making what I thought a valvetrain noise. So far,I haven't found any damage in the top end, so I'm guessing he wiped out a bearing or possibly collapsed a lifter. Found 2 slightly damp chambers on the pass side head, but no damage to the head gaskets. I'm guessing the oil theory is correct, but I was expecting to see obvious damage to the gaskets.

 

Ever had any "Stop Leak" in it?

 

Not to my knowledge. If it did, it damn sure didn't work, cuz this sucker was leaking out of every conceivable place. The leaks were so bad that it would trigger the low oil light about every 75 miles. I drove it home from Philly and it never saw the light of day again until I sold the roller about 2 months ago.

 

I though GM included the GM stop-leak pellets in the original fill, and recommended the pellets with every refill. I never used them, but someone may have.