Shame on me for putting this off but I don't have much green and have another car to drive. 2 years ago my Supra just started over heating for no reason at. I have put 100 psi in the cyilders with no bubbling in the coolant system. If its not real hot the car does just fine but if I drive on the interstate for very long above 65 it starts to overheat very slowly. I know these cars are known for the head gasket problems but I want to be sure that is what it is before I take the head off. I have checked the radiator and water pump and seem to be fine. I have noticed that at idle when its cold it can't keep enough warm water in the heater core to keep putting out heat. If I rev it alittle it warms right up and even when it doesn't overheat it will boil over sometimes after I turn of the car. In the winter time I runs like a top with no problems which makes me think whatever is wrong its not really bad. Any advice would be awesome.

Had the same Problem before, It got so hot that It bubbled in the over flow bottle, Come to find out that I had a Bad thermostat, So take it out, If it still does it then I would think that its your Water pump.

a while back I did run it with out the thermostat it took longer for the engine to heat up but it still overheated. I also took the water pump off and took it to an auto parts store and compared it to a new one, the old one looked just fine, it doesnt leak or make any noise the impeller looks as good as the new one. Any other ideas?

well it seems that the issue has been resolved, but i thought that id add something.

my brother had problems with this before. same conditions. installed a "high flow/volume" water pump (the kind that gives that extra tiny bit and costs another $80) and it behaved a little better. upon further examination, discovered that a section of air dam was missing and so the radiator wasnt getting enough air flow directed toward it. replaced the little skirt thingy, and it was fine. keep it simple, but never rule out the far out.
hope this info helps someone else avert the frustration my brother and i had.

Agreed.

But since you said your running a little low on cash I think you should drain your coolant and flush it with a hose down your raidiator, put in new coolant, and test drive it.

If it doesn't work then buy another thermo at the store and try that.

If that doesn't work THEN buy that high flow pump. You'll save money that way trust me.