loosing coolant thru radiator cap
 

I was working on my car the other day when I noticed coolant leaking out the radiator cap. as a quick fix, I replaced with one from my 5.8 powered truck (my 93 has a 5.8 as well). Both caps were 16 lbs. Drove the car about 600 miles and I noticed when I stopped for gas that there was wetness (green wetness) on the hood above the cap and on my battery (othing pouring out though). Lost a total of 1/2 gallon but no overheating. What gives? The cap off my truck worked fine on the truck.

Check and make sure the fill spout on the radiator is flush, and not bent.

What do you mean by flush?

Even, not crooked

Make sure that the top lip of the fill spout, where the cap seals, is perfectly flat all the way across. Use a straight edge if necessary. Often what happens is someone pushes a little too hard when they are tightening the cap, and one edge of the lip gets bent down slightly, making it difficult for the cap to completely seal, or to lose it's seal at a much lower pressure than the cap is rated for. You need to check that lip and make sure it's not bent at all.

:)

Could be that you've got a head gasket problem and are lifting the 16# cap. First off, check to make sure that the overflow cannister's drain hose is not plugged (blow thru it). Then make sure the hose from the filler neck to the cannister isn't plugged. I had this happen before and blew all the compression out through the cap. Discovered that the hose from the filler neck to cannister was clogged. The excess pressure from blowing compression into the cooling system had nowhere to go but out the cap.

I have also seen the braze between the filler neck and radiator develop a crack. Check there too.

I'll check all of that. She's on a boat to Europe right now so I'll have to wait till it gets there. Bottom line, even w/the 5.8 I shouldn't need a higher pressured cap?