This is going to end up long I suspect. As short as possible. Getting coolant overflow from the expansion tank. Problem is, tank never goes past half full. Pull over and look, and sure enough, there is a droplet on the expansion overflow "vent" and some on the metal below it. Never seems to be enough to drip. No bubbles in coolant, no "smoky" exhaust, etc. I replaced the radiator cap, but no difference. I swore that had to be it, if I'm losing coolant, and apparently know its coming from the overflow, I'm not sure what else it could be. It does seem odd that for some reason, even though the expansion tank is only half full, it is spitting fluid. It would seem to me that if it is half full, it would take a massive surge of pressure to blow it out of the "vent" in the expansion tank. I haven't checked since I put 84 miles on it until today, and the coolant was so low I couldn't see any in the radiator. Didn't overheat, but also didn't pick any up from the overflow tank. I'll have to double check that the overflow hose isn't somehow plugged up, but I just don't get where this coolant is going. Like I said, the thing doesn't leak coolant anywhere I've seen except the expansion tank, and that never seems to go over half full, so I'm at a loss as to where it's going. It runs smooth as ever, so bad head gasket(s) seem out of the question. Anyone got any ideas or similar experiences? Really seems to be just an odd problem.