Ok so im cruising down 75 at 80mph and 4k and after a while the temp gauge starts moving from normal to halfway and back and forth, im just driving it and watching it move. it will settle back and then do it again. sometimes it will go to the hash past half way and then come back. Then a few times the sucker went almost 3/4 the way up and then immediatly shot back down to normal, WTF LOL!!. I was like WOAH, that was fast. I never turned the heater on to make it go down. I dont know what the deal is. I got on it really hard before i shut it down for the night just to see if it would make it go up because it was atleast 15 psi and it didnt budge. however I know that if i dog it really hard continuously the temp gauge will rise up and come back down. any ideas, air in system? if you think its the headgasket, im not to worried, the engine is going to be taken apart in a few weeks.

 

If you are just crusing on the highway and it starts doing this it almost sounds like a faulty sensor or bad connection.

 

it does it cruising through town to, goes up and down. im gonna rebleed it just to see i guess. Im going to replace the sensor when i rebuild my block again.

 

thermostat may be hanging up letting water temps get to high before opening.

its a cheap thing to illiminate.