alright, i've been drivin the car for a couple weeks on the new thermostat, no problem, it runs below half on the temp gauge..

 

so i get in it to go to lunch, drive it 3 miles, look down and the gauge is pegged in the red.. so first thought, ohh ****!! so i pull over pop the hood, the damn thing wasn't even hot.. radiator hoses were normal temp, radiator was normal temp.. engine wasn't even close to hot..

 

i know when a car gets hot like that you pop the hood, you can feel the heat expecially when its 40 degrees outside.. not this time, it was like normal, so i put my hand on the back of the intake/block. not burning hot by any means, just warm..

 

so i start it back up and the gauge moves up to just below the red, then slowly climbs.. at this point i pop the radiator cap, and it took about a 1/4 gallon to top it off.. then i thought maybe i didn't get the air outa the system when i did the thermostat..

so i put the cap back on, walk back around to look at the gauge and its sittin right below the half (normal spot)..

 

at this point i scratch my head, close the hood, and drive off...

i drove about 25 miles at lunch time, and it didn't do it again.. but when i shut it off, i could hear the overflow tank gurgling..

 

i've replaced the thermostat and radiator cap in the last 2 weeks.. it doesn't smoke or leak coolant, that i know for a fact..

just seemed odd that it would peg in the red and be low on coolant...

 

think it was an air bubble? maybe somehting else? :cornfuzz:

this is the RX btw..

Sounds to me like you either have a big air bubble in there somewhere or maybe its the radiator thats causeing probs, i know they like to rust up inside and get clogged, but i'd prolly bet on the air bubble specially since you just did the T-Stat and stuff.

 

BTW........Happy BirthDay