1991 cherokee briarwood 161k 4.0.

about 3 weeks ago jeep was idling in park and i noticed a little white smoke coming from exhaust gave it some gas and some more smoke came out. then it didn’t do it again until a week ago it was a hot humid night just started it up and gave it some gas and out came a cloud of white came out. oh boy. but then it stopped and no smoke. then today it was pretty warm out had the ac on going uphill on the high way i pretty much floored to get up the hill faster looked out my rearview and white smoked engulfed the cars behind me. and then after that id floor it and nothing no smoke. then tonight heading home i stopped for a min and idling it started getting hot past 210 but then once i got going again it was normal like 190. did i blow a head gasket and my jeep is just hanging in there for now?

 

Don't hold me to it but I think its burning oil, the last time I saw white smoke coming from my XJ my oil pressure valve opened and spewed oil all ofer my exaust and began to burn thus making the smoke.

 

humm...i left out a part. when i was stopped and it started over heating i did open the hood it was pretty dark out and the light from my phone wasnt helping i swear i could see some smoke coming from back of engine under intake manifold area.

 

if you're running hot, it's a pretty good indicator that you're loosing coolant. is the smoke coming out the pipe or from under your jeep? white smoke (steam) is coolant. pull the plugs and look for one that is cleaner than the rest

 

did compression test all cylinders are 90 psi first crank or two and 155psi on six or seven cranks.

 

You can tell from the smoke, if its a blueish white smoke and it smells burnt like burnt oil and it lingers in the air... then its oil. if its pure white smoke that disapates very quickly and smells like rotten fruit, then its coolant.

In my oppinion, it sounds like your burning oil. Also 210 at a idle is not hot. Thats the normal operating temperature for xj's. The electric fan doesnt kick on until 217. I would call 230-240 hot...