2001 ST overheating ... running out of ideas ...

[texassizeruckus]

MY 2001 ST Started shifting funny and then overheating about a month ago. Since that time I have flushed the radiator, replaced the thermostat (& O-ring), and taken it to Ford ... where they charged me $600 because the gasket around the water pump was leaking. So I had them replace the gasket and the waterpump since they were already in there. ST had been running great for the past week and then started overheating again yesterday.

It is weird because it only overheats in 5 o'clock traffic w/ the AC on. If I do not turn on the AC on the drive home from work then I have no issues. Also, I can run the AC to work in the morning or at lunch with no issues.

My ST has 62K and is 100% stock. THe only thing that has changed is that I got the oil changed and tranny flushed about a month before everything started screwing up.

One other weird thing ... is that in the winter the black tank under the hood(blower?) "hums" for a little bit when I run the heater, but the heat always blows good and the humming stops after a few minutes. It is very sporadic when it does it. Could that have any bearing with the truck overheating? Any other thoughts???

[budwich]

CHeck your fan clutch. When the motor is not running, you should be able to spin the fan with some resistance. If there is too much or too little, many your fan isn't spinning fast enough to draw air thru your rad to cool enough is heavy traffic.

[rginter]

Sound like your radiator may be plugged up. The extra load that the A/C puts on the cooling system is just enough to overload it and cause the engine to overheat.

[B33p3r]

I agree. Your radiator is probably partially clogged enough to cause you problems. In the A.M. the air is cool enough to cool the radiator. At lunch, you probably don't drive long enough to overheat it. At beer 30 it's hot and traffic is heavy...so your start and stop and it's still hot so the radiator can't handle it. One thing you can try on the way home from work is turn your heat all the way up(uncomfortable I know) and see if you have issues. If the heater throws off enough heat to keep the radiator from overheating...it's the radiator or partially collapsed hose. Hoses can get worn to the point that when they heat up they collapse internally restricting flow.