Okay guys.. the 260z did something funny this morning. I went to start her up.. she heated up just fine.. then all of sudden I’m letting her warm and I noticing something.. its heating all the way up to the little red mark on the guage and then backing back down to halfway. Then it heats back up and repeats the cycle. It hasn’t affected how it runs but I don’t want it to warp the head or anything. The Factory Service Manual doesn’t mention it other than “Check the cooling system”. Only things that could be bad is that part, all others I’ve replaced, water pump, radiator, hoses, belts, the whole nine yards. I replaced the thermostat about a year ago and wonder if it could be going bad again. Thanks guys!