PNWjeeper

so i have a 1990 cherokee 4.0 auto. that has really started overheating AT IDLE ever since it started getting hotter outside. i did a rad flush in january or so and i have replaced the pressure bottle also cuz the old one had a crack in it. when driving at freeway speed (70 mph or so) the temp reads about at the 1/4 line so 180 and by the time i come to a stop at the off ramp it reaches the 210 mark. if im stopped for say 5 minutes its at the red line and coolant is pouring out of the cap from my pressure bottle so much so that i have to pour a gallon of water or more coolant in before its full again. sorry for the long explanation hope it makes sense i just wanted to cover everything.

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92 2dr

my 92 did that i put a second eletric fan that worked of get a dual core radiator

djb383

Other than a flush and new bottle, has any other cooling system maintenance been done? How old is the radiator, water pump, fan clutch, t-stat and hoses? The "1/4 mark" mathematically is 155F and running that cool is not good for the motor either......but not as bad for the motor as overheating.

beefmobile

does your electric fan not kick in?

djb383

Seems like temps in Oregon would still be cool enough to not need the efan IF the rest of the cooling system was functioning correctly.

coloradocherokee

how warm does it get where you live? it just reached the high 70s low 80s here and my electric fan kicks in whenever my jeep is at a stop.

djb383

It's 97 here and rising.......the efan would be on 'cause the a/c would be on. Ours would have to sit idling a long time in +/-80 temp for the efan to kick in, but really don't think it would. Efan on is 218F coolant temp. If all is functioning correctly, wouldn't think coolant temp would reach 218F in 80F ambient.

coloradocherokee

well me and three other freinds fans come on....guessing all our coolants systems are f-d? lol idk....but eletric fans are there for a purpose...to push extra air through the radiator when your jeeps not movin

TheJerm

OP: 1st check the mech fan clutch, should be easy to spin cold, hard to spin hot. Then work from there.

My temp gauge sits at the 150-160 deg range, Used a thermo laser gun to confirm and it was more like 200-220. Can never trust those gauges until you know how off they read

Derision

Oooh, a laser temperature gun! I never thought of that... I'm getting one tomorrow! Where do you point it to get readings?

As for OP... it kind of sounds to me like there's an obstruction in the radiator. If you're driving, the air flowing through the engine compartment is enough to keep things relatively cool, but once you come to a stop there's not enough flow to cool things down. I'd check the temperature of the radiator... is it stupidly hot up top and ice cold below? Also, does turning the heat on full blast make any difference?

tjwalker

Point it directly at the thermostat housing of a hot engine.

I love my infrared point and shoot temp gun. I use it for a LOT of things, not just automotive. Great for troubleshooting electrical hotspots, heck I even used it for a medical situation once (but most of these are NOT designed for medical).

I bought the Raytek MT6 on Amazon for around $50. Raytek is a great company. A great tool for the tool box!!

cranesrule

Fan clutch. Replace it.

djb383

What r the odds of 3 other hot running XJ's? LOL. Do a search on "overheat" and check back in, in a few months, when u r finished reading. What about those XJs that DID NOT come from the factory with a efan?......they're out there. Ask yourself why my XJ would be running 218 in 80 degree ambient, presuming a/c is not on. There will probably be +/-300 overheat posts/threads over the next 2-3 mos alone. The XJ cooling system is not to be taken lightly. FWIW, the fans pull, not push, air thru the rad.

PNWjeeper

Ah yes the Efan it doesn't kick on at any temp but does if ac or heater is on. And yes running the heater does work but it mostly just slows the temp from rising.

PNWjeeper

You know I think the mods should add an overheating section. And I tried sifting through the overheating search mess... Ugh that was terrible.