I have a 2000(YES 0331) jeep xj and have put new radiator, thermostat, water pump, belt, electric fan always on, fan clutch, coolant flushes, 50/50 coolant, all hoses.
(Note. I have done combustion test at professional dealer and no signs for leak. Compression tested perfect, no coolant in oil, block tested, nocoolant loss, 20-25 psi oil pressure at 210f, idle 500-700)

Here is what is happening, I will drive just fine down the road at 210 but when I idle it gradually gets up to 220 and then (in 1 second) all of a sudden oil pressure goes to 0 and temp shoots upto 260 and coolant boils over.

Also I recently bought a temperature gauge. With the heater on it sits at 208 (pointing at the thermostat housing) but when I turn the AC on it gets up to 230+.

idk if this makes a difference but when I pointing it next to the thermostat housing at the engine block it was at 254 with

I'm clueless.

 

That's bizarre.

New fan clutch? That's the first place I would have looked. Hmmmm. Is your serpentine belt routed incorrectly?

 

yes it is I made sure! Thanks!

 

your thermostat could be sticking, then flash fries the temp sensor when it does give way.
fan shrouds are they intact? Try a new Radiator cap just because its cheap. i know you said much of these are new but they can be faulty and they are cheap/ easy to try.

 

Appreciate the response!Literally I've tried 3 different thermostats, and on my 4th cap

 

Are the fins in your a/c condenser(in front of the radiator)clogged?

 

I sprayed degreaser for 5 minutes to clean it out and it is spotless but it does have a few bent fins.

 

are all pullys spinning freely? is the temperature sensor new? i dont think it could cause a problem but was any kind of stop leak ever used?

 

temperature sensor is probably original one from the factory, pulleys spinning freely, not sure if there was any stop leak used

 

Hmm now that you mentioned it this was the color of the coolant for like 3 flushes. Is this stop leak??

 

Looks like a crap load of oil

 

or bars leaks....

 

Yep, could be. Or oil.


I'm wondering if the exhaust gas test was done incorrectly. This has all the signs of an exhaust leak into the coolant.

 

Hmm bars

and i I did the combustion leak my self and had it done at a very reputable mechanic.

 

that... Looks like oil to me. If they used bars you probably have a bad head gasket. Not all head gasket leaks are the same, I would get your system pressure tested vs a exhaust leak. but if you have that much oil in your water, I would bet you have that much water in your oil and your engine is probably not good for much longer.