Okay heres the story. I have a 2002 chev venture van with v six. has 136000 miles on it. two years ago had head gasket replaced. this spring alternator. other that no issues. well three weeks ago i am up at the cottage and start to head home. 70 miles. get about 5 miles down the road and notice that the temp gauge is almost in the red. pull over pop the hood doesnt seem to be boiling over no steaming or glub glub sounds. overlow tank is at normal level. i take off radiator cap radiator is full. i put cap back on start vehicle and gauge goes back to normal and runs fine all the way home. drove around for 2 weeks no problems. last weekend up north again go to head home and it climbs in the red again. so i do all the above and start van but this time temp stays hot. i let it cool down about 20 minutes started up again and temp is normal for about 3 or 4 miles. then climbs high again. then drops down to almost normal for a couple miles then climbs high again. finally pull it in to a service station tell him whats going on and says thermostat. so he replaces thermostat, i drive home 60 miles everything normal. drive the van all week back and forth to work with no problems. friday night time to head up north again and drive the 70 miles with no problems everything running great. sat morning want to run into town and about 4 or 5 miles its overheating again. get it to a friends house up there, he figures air in the system not letting thermostat open. so he bleeds the system off i take it for a ride about 20 miles and everything is back to normal. now time to come home today and the same thing it overheats. i bleed system like he showed me and i drive the rest of 65 miles home no problems. at no time did i lose coolant. my question is what the heck could be wrong. any ideas
