Hello! I've spent the weekend check out my new z28 and I have a question I could use some advice. http://www.nastyz28.com/forum/showthread.php?t=222864 It's a 1979 Z28 w/ 350 Auto trans and HD radiator. Dual exhaust but otherwise stock appearing. I just got the car so I don't know a lot about it. One thing that's a bit troubling is something going on with the cooling system that I've never seen before. First, the car does not appear to overheat. In fact, underhood temps are pretty moderate even on the cool side. Checked with the car running and the thermostat housing only got up to about 190. I drove the car about 80 miles when I picked it up and was surprised how cool it was underhood. The gauge does not work properly, although the sending unit has Teflon on it so that may be affecting grounding/reading. So here’s the problem – when the car gets to operating temperature, the level of coolant in the radiator rises and falls pretty dramatically. It will suck down maybe 4 inches, then suddenly go back up and puke some out (just a little bit). Then go back down, and suddenly go back up and puke some more. I don’t see any “bubbling” which would indicate a head gasket, and the exhaust smells normal with no smoke. I tried “burping” the system twice, and it almost doesn’t matter what I do - coolant will fall, rise, puke, fall, rise puke. Pretty regularly. When I rev the throttle, the coolant will stay down. But back at idle, it will do the same thing. Also, the system does not pressurize. I did a pressure test on the system and it appeared to be OK (in that at 16lbs, it would drop, but very slowly). I tested the cap and it was bad (new cap on the way). I put a known good cap on the car but have not had a chance to see if that fixed the pressurizing problem. When I shut the car off hot, I can hear/feel gurgling from the thermostat and upper radiator hose. Has anyone seen this before? I’m hoping the bad cap is the problem, but the surging tank at idle is unusual to me. Thanks!