cooling system question- didnt find answer by searching

i have a 96 xj and it has smelled a little like coolant for a little while now- i notice it when i park but havent found any puddles or wet areas. i replaced the upper and lower hoses, thermostat, and flushed about 4-5,000 miles ago and all is dry in those areas. i do have to replenish about 1 gallon a month into the reservoir bottle- dont know what is considered "normal". today, after an oil change, i was running the engine to check for oil leaks when a quick burst of coolant flew into the air - not a heavy and solid stream but just a mist. i shut it down and went to investigate(cussing) and found that it was all coolant covered near the radiator drain XXXX on the passenger side. i felt the upper hose - it was hot and firm as a rock. im wondering if either the rad cap has failed and wasnt letting pressure escape- causing my rock solid upper hose and coolant burst. or, if maybe a thermostat problem is at hand- upper hose is hot though. after a little while, i opened the rad cap while the engine was still very warm and there was no pressure at the cap when i opened it. am i on the right track with getting a new rad cap? does this seem to be my problem? my engine never actually runs above 200 degrees if its 80 outside.

Find out exactly where the mist is comming from. I had a Dodge truck, I loved the thing, but the radiator had a pin hole in it and there was a mist of coolant when the thing got to operating temp. You can replace the cap, it is cheap and you can cross your fingers. And yes you shouldn't have to replace any coolant ever. The only reasons to replace coolant is hole in cooling system, bad head gasket, hole in system, overheating, hole in system and hole in system. Did I mention hole in system yet?

There is a little weep hole in the bottom of the water pump nose, when pressure gets to a certain point it can push thru the packing that surrounds the shaft, squirt out and hit the running fan belt/pulley and that can atomize it to a mist.

I also noticed something the other day when I was replacing the rad on one of our TJ's. The rad fins and core looked OK from the front thru the grill, other than the top tank leaking from where it was crimped on it looked OK. After I got it out the back side was horrendeous, the core was gone from the top two inches of the core almost all the way across and the majority of the core back there was rotted away. That fan shroud can hide alot of bad stuff and on a 2.5L TJ that fan shroud is about 20" deep so it's kind of hard to look thru.

thanks guys ! i do appreciate the responses. i guess what i will do is pressure wash the whole thing and take it to a rad shop to have them pressure test it to find my leaky hole. thanks again!!

I had a similiar mystery leak. My upper hose was rotted where it clamped to the radiator.

Cut the rotted part off, clamped it down tight.

That was about two months ago; changed the hose to a Mopar one today.