Was driving on Interstate, smelled coolant, noticed temp gauge at max, pulled over. Coolant spewing everywhere under the hood, both side of the engine, everywhere. Did not open hood. Had car towed home. 2 hours later, refilled radiator and overflow with straight water and cranked. Let run for 20 min til it hit operating temp and fan kicked in. Drove around the block, revving the engine. No leakage. Not a drop. Temp at operating range. What the heck?

 

You have maintenance to do. Don't drive it anymore till you find the issue.

First things first, drain the oil and see if there's coolant in it.

Shoulda popped your hood to see what was going on...

 

As stated, u have maintenance to do. Don't run straight water for long or u will have a rusty mess from the iron block/head plugging the small passages in the rad and heater core.

 

Thermostat stuck?

 

i checked the oil. looks fine. i don't know how to troubleshoot without just running it to recreate the episode.

 

and i didn't pop the hood cause it was spewing everywhere and i didn't care to get burned. i was also on the side of an Interstate and 18 wheelers were buzzing by at 80 miles an hour.

 

im wondering that as well Kingfisher.

 

can't find anything wrong with any of the hoses. radiator looks fine. perplexed.

 

i had a similar issue, turned out that the radiator was partially clogged internally. It would drive fine around town, but once under pressure on the highway it would overheat. DO NOT drive further till you figure this out. You do not want to turn a simple radiator swap, or similar procedure, into having to change a head gasket. Simple way to check the thermostat is to check and see if the upper radiator hose is getting hot after the jeep has gotten to operating temperature, and, although not determining how efficient, it will prove that your water pump is pumping. I would then check to see if the hoses going into your heater core are both about the same temperature, helping to rule out a clogged heater core.

 

thank you for that. this is helpful. last night after work i drained the radiator and flushed it with the garden hose. the water that came out of the radiator was clear. the water coming out of the block looked like river water. i filled the system with plain water and ran it up to operating temperature. drained it again. clear from radiator, river water from block. never overheated or leaked anywhere. checked all hoses thoroughly. took off the filter box for access. final fill with coolant and hose water. just to get me through the work week. i only have to drive 7 miles to work, no freeways. plan to take it to a mechanic friday morning for a thorough diagnostic and a proper flush. i'm wondering if the radiator cap was loose? i drive on forest service roads often and things get rattled around and broken. a friend told me that happened to him once. when i get home today from work i'm gonna run through your suggestions. thanks again.

 

i've been in the same situation with mine. it has been running hot off and on for the past several months. i took it on an 11 hour road trip and didn't have a problem, but it will also overheat when i drive to the grocery store from time to time. i knew the radiator was clogged pretty bad when i purchased it, so i ran an extensive flush, back flushed the heater core, and replaced the t-stat and cap. it did better, but still had trouble from time to time. i put new clamps on all of my hoses to make sure there were no leaks. it has a new water pump, the fans work fine, i get good compression, and i've been baffled too. i just received a new radiator today. i figure replacing the radiator has got to be the final solution. i've read that when the temperature spikes to the red line, it is not an accurate reading but more of a "warning" to get you to hurry up and pull over because it is running a little hotter than expected. my problem was that the reservoir was boiling over once it was up to temp and i turned the key off.

 

ran some more diagnostics. all hoses get hot except the lower hose from the water pump to the radiator. it only gets warmish. water in overflow reservoir starts boiling when it gets to operating temperature. gauge in car dash fluctuates mildly. have not "overheated" per say but i have not driven it more than 10 miles at a time since the boil over. i'm beginning to think it came from the overflow and the fan blew it all over the place. possibly clog.

 

One time I noticed that the water in my overflow was boiling and it was due to having a faulty radiator cap. If the cap doesn't hold the right pressure, then the boiling point is lowered.

 

well i replaced my radiator yesterday and it has shown remarkable improvement. the temperature pins just under 200 and won't fluctuate on the highway, idled, or 4wd. i'm happy so far.

 

Be sure to check coolant level in both the rad and bottle, MOTOR COLD, for several days. Add coolant, MOTOR COLD, if needed.