I'm having serious issues with over heating on this pos closed system on ny 90 xj. Should the fan come on as soon as I turn the jeep on? The jeep overheats just idling for about 5 minutes and the fan never comes on. When should the fan kick on? Could this be the answer to my overheating issues?

 

You are referring to the electric fan right?

 

I believe so. Its the big one between the radiator and the power steering pump.

 

That turns on with the A/C. You have another issue. Could be thermostat no opening.

 

Just replaced my thermostat. I took off my water pump but can't tell if its bad or not. Nothing is loose on it.

 

Propellers still in good shape?

 

How do you know it overheats? 5 minutes seems like barely enough time for my JEEP to get up to operating temperature.


I'm not too familiar with the '90 design...there are tons of threads on methods of properly burping the air out of those cooling systems. Maybe you have air trapped in the system??

 

1. convert to open system.

2. Flush the system

3. Go ahead and put a new water pump on it while you have the old one off. They're cheap.

4. If the system is really cruddy when you flush it then replace the radiator. (If you convert it to open system you'll have to replace it anyway.)

The electric fan should come on with the A/C and when the Jeep get's too hot.

What temperature is it getting to?

 

I know because it pegs out and starts overheating. I can't get it out of the driveway without it being in the red.

 

I've got an open system in my 99 xj that has a thrown rod. Is it easy to convert it over? Do I have to do anything to the engine itself?

 

maybe check the sensor? that's the cheaper and easier end that workload.

 

Radiator, hoses and over flow bottle. That's it.

 

Does your oil pressure drop dramatically in the time it takes to heat up? You can get a radiator cap that has a thermometer in it for a few dollars more than a factory cap, or use an infrared pointy thermometer. Verify it's not a sensor before blowing a wad of that oh so precious cash.

 

Oil pressure is just fine.

 

probably just the sensor. oil pressure would drop as it gets hot.