your temps dont sound too bad if you have a stock temp t-stat. even if you have a 180, but it is warm where you are, that is not bad.
get a new cap. if the cap is not sealing, it is likely not holding pressure. the pressure (~16 pounds) helps to raise the boiling point. so you could be boiling water off, and running the system inefficiently.
Hey thanks man, I've been around the boards for awhile and gotta say you're one of the most helpful guys yet. I got a new cap, it seals, no more overflowing and the temps are finally back to normal. Thanks for all the help everyone.
Rerun, thank you for the kind words. i try to help out as much as i can - until about a year ago, i did not have a computer (i'm a caveman, you know. LOL). anyhow, i had to figure out everything on my own. i love the forums, so i try to pitch in where i can.
im very glad to hear you are up to snuff. after i posted, i checked your location, and it sounds warm (in Tucson, we have been flirting with 100* - 98* today), so with those temps, around 200* sounds fine. and if you have a stock 192/195* thermostat, that is exceptional. with a Mr. G 180 (and all renewed cooling system), i run 185-190 in traffic in 95* ambient temps, and around 195 with a/c on.
if i did not mention it, the puter pulls timing at 226* (IIRC), so that is the temp the factory felt was getting a little too warm. also, if you dont have one, i highly recommend an aftermarket temp gauge. i was shocked to find out what temps i was running at, once i installed one (the stocker sat happy and dumb below 1/2 way, while i was running at over 200*). not cool (pun intended).
but again, im glad to hear you are running cool now. pat yourself on the back - nice work!