Overheating Problem Need Help

[mustang86gt]

have a 86 gt I can drive it a good 30 mins before it starts overheating in traffic or highway it doesnt matter. its got a new water pump,thermostat,radiator cap and the radiator and fan are good. we have tested for head gasket leak and they checked out fine. i still think it might have a slow head gasket leak but idk any input would be greatly appreciated

[USMC302]

1. make sure the waterpump wasn't a reverse flow one, they sale those reman ones that way sometimes.
2. 30 min sounds like the thermostat isn't opening, what temp is it?

[mustang86gt]

no its not the reverse i checked that before it went in and we've replaced the thermostat and checked it again and thats good its a 180 by the way. the highest temp iv let it get to is 230. i can pull over and let it cool back down to about 190 and i can go another 30 mins without it heating again. it will hold at 190 or a little below the whole 30 mins then once it goes above 190 it keeps going

[goodyear1984]

do u have a clutch fan? if yes grab a hold of it and see if it has play side to side in it

[mustang86gt]

yeah i do but very little play

[goodyear1984]

replace it u should have no play at all!!

[goodyear1984]

you should put an electric fan on it

[USMC302]

Originally Posted by mustang86gt

we've replaced the thermostat and checked it again and thats good its a 180 by the way.

What did you do to test it? It really sounds as if the water is not circulating through the engine

1.Try running the car with no thermostat at all, see if it stays below 200, if it does, then the thermostat was bad.

2.Try putting a new radiator cap on, there needs to be 16lbs of pressure in the system, caps go bad too.

3. When was the last time you flushed the system, are you running a 50/50 water/antifreeze mix? Flushing will also help dtermine if you have any blockage as well.

4. As goodyear mentioned, the clutches on those stock fans are crap not to mention useless if you have removed the fan shroud or if it's broken. It's purpose is to help draw air through the radiator.

5. Double check the waterpump, brand new ones from the parts stores can be bad from the start, it happens all the time. Also look at your belt routing, if your using a short belt, be sure to keep the same directional pull as the stock belt...
6. Finally, try adding some water wetter, it works.

Really all I can think of here...besides maybe your gauge is acting up, which I doubt. Try some of this and let us know....Good luck.