Lifter knock

Got a question, Thursday night I drove my wifes 3.8 01 Impala and started it cold. It instantly had a very loud lifter knock. I thought, oh crap she ran it out of oil. I checked it and it was about a qt low. Shouldn't be knocking for only a quart. Once the temp reached 140 the knocking completely quit. I have had all of the "low coolant" problems but haven't changed the gaskets yet. I figured I would go ahead and change the oil. Well there was signs of a little bit of coolant in the oil. I figured it was time to go ahead and change the gaskets. With all that done and new oil in, I started it up. It again started knocking like crazy until it warmed up to 140 and went away. I called a former GM mechanic buddy of mine and he said that there was probably some water still up in the oil journals and that is what is causing it to knock. and that it will probably stop after I put a few miles on it and change the oil again. Has anyone got any insight on this or has it happened to anyone else? He was really shocked and said that the 3.8's were really tough and couldn't imaging having lifter problems.

Oh and after looking at the bad gaskets, I don't agree that DexCool caused it to go bad. They were crushed around the rear water jackets on both sides. It looks more like a bad gasket design rather than an incompatibility with the coolant. I do still agree that DexCool is inferior to the green stuff though for other reasons. I have also been told by three mechanics, one independent, one former GM, and one GM mechanic that it was indeed the gasket design, not the dexcool.

Head gaskets are not usually the problem with this engine unless over heated, the upper intake was the culprit. Anyway see if you can pinpoint which lifter and focus only replacing that one. I'd check the oil pressure with a mechanical gage and make sure there is no left over coolant in the lower engine.

My upper plentum wasn't leaking. It was my lower intake gaskets that were. The knock is gone and everything is back to normal. There was probably still a little coolant left in the top of the engine. I'm going to change the oil again tonight just to be safe.

Thanks, Chad