2000 ex overheating mystery HELP!

[bates]

ok my buddy has a 2000 ex, xlt, with a sohc. its overheatiig so he took it to a goodyear place and they tested the thermostat, its ok, waterpump, its ok, and pressure test, its ok. and theres no antifreeze in the oil... so heres what happened, when he left in the morning the gauge was bired inthe cold, below the c, and so he started driving and after quite a while it finally came up, then it started goin up real fast, light comes on, he slows down, gauge goes down.... he said it was more relative to his speed than rpms....
so then he took it to the stealership cause goodyear had no clue, and now the stealership has no idea but someow they will have it ready by midmorning tomorrow.... weird eh?

Anybody got any answers??

 

[RiverRat]

Originally posted by bates
...now the stealership has no idea but someow they will have it ready by midmorning tomorrow.... weird eh?

I like that quote

It should be something real simple. Once there was a Mistake (Mercury version of Contour) that no one could figure out why it overheated. Well it turned out to be a defective radiator. You couldn't see light through it. Air was going around it and not through the fins.

 

[TPLYNCH]

I'd say Fan clutch but the problem is reversed... Hot while running, cools while idling. Normally, it's the opposite cause the air rushing thru while driving will help cool the engine...

 

[bates]

thats sorta what i thougth too, at first i thought thermostat, but they said it checked out....i spose they could be wrong but i justdont know

 

[Robert]

A bad thermostat and a bad waterpump can both cause your engine to run hot while driving and run cooler while idleing. When you are idleing, your engine isn't working as hard, so it isn't generating as much heat. Once you step on the gas, your engine has more work to do. If the thermostat is stuck closed, it isn't allowing the antifreeze to circulate to the engine to cool it off. If the waterpump bearings let loose, the impeller will stop pumping the coolant through the engine which will also cause the same symptoms. I've had both. I had a Toyota pickup that lost its waterpump causing it to run hot anytime I got above 25 MPH, and on my Explorer my thermostat stuck closed. I could literally watch my temperature gauge go from the middle to H in the few seconds it took me to go from 0 to 45 MPH. I know you said they tested the thermostat. Since the only proper way to test it is to remove it and boil it in a pan of water, I hope they went ahead and stuck a new one back in. If they didn't, I would try a new thermostat first. Next check the waterpump.

 

[Doug]

Sounds like the t-stat, the same thing happened when mine was on its way out. I thought it was the water pump but put i pulled out the t-stat to see if i could isolate the problem and turns out it was just the t-stat.

 

[bates]

ya those basterds were retarded... they said they checked it, charged him for a new gasket to put the old one in! didnt put a new tstat in cause theyre f'in stupid, then the stealership said o ya it needed a tstat, so they throw one in, go for a ride and OMG! its fixed! go figure eh? so then my buddy gos back to the original place(goodyear dealership) and *****es at them for what they did and he got his money back! problem solved.

Thanks for ur help guys!

 

[Doug]

lol, on both my explorer's i had problems with the cooling system. first time it was running cold and the 2nd time it was running hot. both times it was the t-stat. its the easiest thing to check in the cooling system.