Another Heating (Temp) Question

Well yet another heating problem. As I run down the road at 55mph my xj temp goes up to the red, but as soon as I turn the heater on it drops to 210 ASAP.
Here is some info on my xj
1992
4.0, 5 speed
5" lift w/31x10.50x15
410 gears open front rear lock
new water pump, clutch fan, hoses, thermostat, belt, aux. fan, wired a switch for aux. fan to turn on with key switch.

Any thoughts or comments would be appreciated!!!!

Bo

sounds like a water pump problem, since fans dont really do anything at that speed, I would check your thermostat first.

Ok, I guess anyone could get a bad pump or thermostat from Autozone..


Thanks

Heating up at speed like that usually indicates that the water isn't flowing through the system like it should. Turning on the heat gives it an alternate route for flowing and additional cooling.

Like jeepdude10000 said, the first thing to check is the thermostat. If it is not opening fully it could cause this kind of a symptom. The second thing I would do is a thorough flushing of the system, to insure that there aren't any blockages anywhere. That, too, could cause these symptoms. Then I would look at replacing the water pump.

Good luck!

How gunked up is the radiator? My Van would do the same thing, it was the radiator.

I second the radiator. Make sure it's not blocked.

Did you put on a new lower hase? If you did does it have a spring in it? If it doesn't it will colapse(sp) on itself. I had this happen on my 96, removed the spring from the old hose & put it in the new one. It hasn't happened since. JIM.