Car keeps over heating

The dam camaro keeps overheating.. but.. only on the highway.. it will slowly start to climb to and pass 240 before i shut it down. But if im in traffic or here in town.. its only 220 and stays.. it started 2 days ago. usually it would run about 160-180 (160* thermostat, which i replaced today). Both radiator fans are on, and the fluid is full.. If im on the highway and i get off an exit and sit with the engine idling. the temp will start to go down, but its still running hot. Any idea's?

thats seems horribly backwards from anything that should happen...

i know... it pisses me off something fierce im out of idea's.. well .. one left.... someone at work suggested it... it will cost me ... i think 2.05$ if i want the job done right... a gallon of gas.. premium.... dump it on the car and stand back

maybe its the control swich.. or the relay swich... maybe giving me a false reading.... becasue yesterday the engine read 260F... in the red... but i remember there was no steam or bubbling from the overflow or the radiator......

Did you check the water pump to make sure it's working properly?

You didn't say anything about that, it's the only reason I ask...

Sounds like it could be a bad pump..

Your rad or coolant lines could be plugged somewhere.. make sure your rad cap is working properly and your overflow levels are as they should be..

Other than that, im gonna say bad temp sender?

yea maybe your water pump is pumping enough water at the higher rpms

It sounds like you might have air in your cooling system. I have had this happen on a few cars.
What engine are you running? If it is the LT1 there are air bleeder screws in the smaller radiator hose and on the thermostat housing. Run you car for a while and let it get up to operating temp then shut it off and let it cool then open the bleeder screws. If air comes out this should fix your problem, but if it doesn't and anti-freeze comes out you have another problem. :banghead: I was banging my head against the wall when it happened to me.

its the L98 engine.. no air in the system.. checked that yesterday.. Water pump... hmmm... didnt check that... what sound would it make when its on its way out? And how do i check to see if its working right?

ok ... i replaced the water pump today... still heating up... replaced the thermostat.. still heating up... flushed the system.. still heating up.. got any air ouft of the system.. still heating up. what do i do? it heats up on the highways... or above 45.. and cools down in traffic... wtf

is your radiator clogged?

how do i check to see if its clogged.?

well you can check to see if the fins are clogged with dirt and little rocks and stuff by removing the support and fan shroud, and you could prolly check the channels by unhooking your radiator hoses and spraying a hose down into it... maybe someone on here will know of a better way

no the fins and everything are fine... i dont get it:( :banghead: :banghead: :banghead:

hmmm...thats a doosey of a problem

ya i know.... im going to be selling it... i live in ct anyone want it? 2500 obo

and im looking at a 1994 camaro. 5.7 auto... what kind of problems are with them and what should i look for when i drive it tommrow?

basic car stuff, im sure you know, these cars do not hide problems well. look over the car for your standard stuff: rust on the chassis, body damage, listen to the timing and the valve train, get all the repair info...

R U HOT

yes, very. come to me... :2cents:

their should be 2 temperature sensors one tells the gage how hot it is the other tells the computer how hot it is. if your gage reads hot but your not boiling over it is probably the sensor to your gage pull the wire off of the sensor and ground it your temp gage should go all the way to the hot side. next check the sensor to the computer do not ground it. check it with a volt meter I think it should read 5 volts

hmm i had a problem like that in a dodge daytona i used to own.

i rewired the fan to a swich in the interior, and all was good. i dont know if it just wasnt turning the fan on on the highway or what, but that did the trick for me.

like said above, that is something totaly opposite of what would/should happen. wierd

Make sure the plastic front air dam is still on the car. I have been a Gm dealer technician for about 20 years and I remember when those cars were new we had to install the air dams during the new car service. If you drive the car at highway speeds with out the air dam it will overheat because not enough air will get to the rad. If it is still there I would start by checking the timing it can cause this if it is really off.

After I posted this I see your other post that you figured it out, I thought that was your problem.