ok sorry for making yet another overheating thread but im stumped!

last weekend i flushed/refilled my coolant, replaced the thermostat, and bled the system thru the heater hose plug. drove it all week on some intertstate driving and some gridlock traffic and everything in between, the temp stayed normal the entire time. then i get on the interstate at noon today cruising at 77 a/c on as always (its been in the 90s here) and after about 20 to 30 mins into my trip my temp started creeping up and continued to so til it got up about 75% of the way. then i turned the heater on and it went back down to normal temp.

so when i got home i popped the hood and heard some kind of gurgling noise back by the throtte body. and im worried cuz i noticed once the car started running hot the oil pressure was a little lower than normal. the coolant level is still good no leaks and both the fans work. anybody have any ideas on what it could be?! thanks!

 

Air in the system.

 

wouldnt it have overheated alot sooner if there was still air in the system though? i drove it alot this week and the gauge never went past the normal point until now

 

Sometimes the air would move and get stuck at the thermostat and keep it from opening, when that happen just put the car in neutral and rev it to ~5k rpm 4-5 times to move the air, you will notice the temp needle start to go down. (you may need to try that 3-4 times)

For me, before I fill the system with coolant, I disconnect the throttle body water lines (to not trap any air in the system) and start filling with coolant at slow but steady speed until the coolant start coming from the TB lines. Works every time.

 

spill free funnel and rebleed.

These cars are POS when it comes to trapping air. Sometimes it takes weeks of driving to get it all out. I've found that the spill free funnel (about 20$) usually takes care of it but sometimes you can have a bubble trapped and then later after driving a while it comes free and gets re-stuck in an important area (behind the thermostat).

 

Well I just checked the level and it went down some so I topped it off and drove it around with the ac on for ten minutes or so and the temp stayed normal the whole time. I dont get it if there was air by the thermostat shoulnt it still be running hot? I don't get why it would overheat on an hour interstate drive but not any other time

 

because the air must have moved during driving. Sometimes it just takes a matter of time before the air traps itself somewhere that causes a problem.

 

I had the same problem. WHat i did was remove the upper radiator hose and poured coolant thru that hose until it starts to drip out of the radiator. Reconnect and i've been good. Also what i did when my thermostat failed and i was waiting on a new one, i cut the springs and lock inside the thermostat and just drove with it being hollow.

 

i figured id update this thread. i brought it to a shop and they used some contraption to force the coolant through, filled it up then bled the system. it worked great for 3 weeks or so til i took another 1.5 hour interstate drive during the middle of the day (2pm friday) with ac on. started overheating again so put the heater on to cool it back down. i was dying it was 98 outside! the weird part is when i made the same drive back at 7pm today the needle never moved. the only guess anyone can think of is the radiator is clogged?

tldr: car only overheats on interstate drives longer than 30 mins when its really hot outside, ac stays cold no matter how high the temp need goes

 

If your system isn't working optimal due to a restriction (or otherwise) then turning on the a/c will make it worse. The ac evaporator is right in front of the radiator throwing 150* heat back onto the radiator thus heating up the coolant more.

have you checked for a head gasket leak? It sounds like it was properly bled so the only thing causing it to work for a while then start to crap out is if air was being forced into the system via combustion chamber.

 

hey jeff i appreciate the help! ive been driving it everyday and checking the oil and coolant every 2 or 3 days and see no signs of anything wrong. oil is clean, no smoke out of the exhaust, no loss of coolant. but before this turns into a bigger problem im dropping it off at my shop in two weeks for a compression test and to see if the radiator is clogged. so as soon as i found out whats wrong ill post an update.

 

I know its been a while since this thread was active but I am wondering what was your outcome after the compression test? Did you ever solve the problem? I am facing similar problems with my car.

 

Change the radiator cap!

 

oh thanks for the bump i forgot to reply. it turns out my radiator had a bunch of build up in it on one side and that was restricting the flow. i put a new in and its been fine!

 

awesome, good to hear it's fixed!