Ok so in my 91 xj i have a cooling problem. It gets pretty hot when idling. like 240 or so. It will cool right down as soon as i drive away. I have a new thermostat, coolant 50/50, radiator cap, and mechanical fan clutch. The E-fan will only come on if the AC is switched on. Im kinda at a loss on this one.

 

Sounds like the water pump might be on its way out.

 

shouldent the Efan come on at 218 or so.

 

Yep,218 or so.

You may not be getting proper air flow at idle/low speeds. You ever pulled the radiator and powerwashed the fins? Also do the a/c condensor before you put the rad back in if you have one. Took me a good while to get my original '96 ones cleaned out.

 

ok cool i will have to try that. There isnt a temp switch telling the fan to come on at temp?

 

Ok so it probably has nothing to do with it but I unplugged the temp sensor on the thermostat housing and the electric fan came on.

 

As it should do. The TCS sends a signal to the PCM for various reasons. One is to get the fan turned at a around 218*. One other reason I know of is so that PCM can adjust the fuel/air mixture via the ICA. Remove the TCS and polish the probe with an abrasive pad until it shines. It's what was causing my ICA to malfunction and giving malfunction codes 22 and 25. Cleaned the probe and all was good. BUT if that doesn't work the TCS could be bad.

 

At 240 do this if fan comes on replace sensor .