overheating...

O

OhioMike

New member
98 cherokee 4.0

so the wife gets upthis morning to go to school...comes in and asks if there is a such thing as getting so cold the heater doesn;t work...i say of course...is the jeep heating up?

she says yes it;s in the middle...of course she;s a woman so i go to investigate...

she takes my truck to go to school...in the meanwhile i go start the jeep and it is runnin about 210...no heat...so i go check to see if the radiator is frozen over or somethin...and the fans are working...

the fans are working...the overflow bottle is not frozen...i crack the radiator and it spits out some fluid...i get back in the cab and watch the temp...cause i suspect it will start to rise pretty high...but it only gets up to 235 or so...then after a few minutes...shoots up to the redline...not a gradual increase but like the thermostat opened and let hot water into the block...i shut it off...

it did run a bit rough but i don;t think it was hurt...and i never got heat...

the water pump and thermostat are new replaced last fall...

i was wondering if the heater core could be bad or frozen...cause this really doesn;t make alot of sense...

ideas...
 
Sounds like something is frozen somewhere. looks like you did some cooling system work. Or did you have it done? I would check the coolant and see what temp it's good to. I mix mine 70% antifreeze, 30% water. They do have some pre-mixed stuff, could you have gotten that by mistake and mixed water with it? straight antifreeze can do the same thing, if I remember correctly.

Do you have someplace where you can bring it in and warm it up?
 
Agree, it's froze some where, My GF had the same thing happen to her car, she wasn't keeping a good mix of antifreeze so it froze somewhere, nice thing was that I was able to open the hood and leave it running without it overheating it was so could out, think it was -2F at that time in the morning. I then made sure we had a good mixture of antifreeze and let it circulate for awhile.
 

Id recheck-replace the thermostat----after I made sure the coolant was okay. Sounds like thermostat never opened up. If coolant wasn't okay, more than likely it would have pushed the freeze plugs out and water pump would have not rotated and the fan belt would burn up.
 
OH, forgot to mention it was in the bottom hose, could feel it when u squeezed it, The pump turned and no plugs on ground, was the first thing I check so it hadn't been long enough for the rest of stuff to freeze up. Was a good point to bring up though.
 
mrfast said:
Id recheck-replace the thermostat----after I made sure the coolant was okay. Sounds like thermostat never opened up. If coolant wasn't okay, more than likely it would have pushed the freeze plugs out and water pump would have not rotated and the fan belt would burn up.
Click to expand...

If the thermostat did not open wouldn't it still have heat? I thought coolant still circulated in just the motor. It sounds more like a blockage to me. Maybe in the heater core? or one of the hoses going to the heater core . I would guess those will freeze before the block.
 

It's been awhile since I have done that kind of work, but if thermostate is stuck closed water will not circulate in block or heater core and I think that is why motor temp went sky high very quickly as motor warmed up
 
Forgot to mention if heater core is pluged up, of course your heater won't work but it will not cause your motor to run hot---maybe a little warmer, but the anti freeze will go ahead and ciruclate through your upper and lower radiator hoses--but the thermostate has to be open to circulate.
 

My XJ is a '96 and there is a valve on the passenger side firewall where the hoses go into the heater core. This valve is controled by vacuum and opens when you turn the heat on, allowing the warm water to pass through the core. I had to replace mine, was about 15 bucks!! Heat works great now!!;) Yeah might want to check that mixture too!!!!
 
wstall77 said:
My XJ is a '96 and there is a valve on the passenger side firewall where the hoses go into the heater core. This valve is controled by vacuum and opens when you turn the heat on, allowing the warm water to pass through the core. I had to replace mine, was about 15 bucks!! Heat works great now!!;) Yeah might want to check that mixture too!!!!
Click to expand...

I had to replace that in my 96 also. Jeep couldn't decide what the heck they were going to use over there, it seems like every year has a different setup! :lol:
 
Could it be that you had an air bubble in the system somewhere? My boss's truck was doing that last week. It would run hot, but no heat from the heater. You could feel the air bubbling through the hoses. Finally figured out that it would get trapped in the water pump and cause cavitation, and no water would circulate, so it then would overheat. Something to check on, I suppose.
 

When my '00 started overheating, I found through a little research that the gauge is not entirely accurate; it'll go up to about 235, and hang there, so you think everything's OK, then it blasts up to 260 when you're really overheating quite badly... Guess it's a thing on the 97+ instrument cluster... Just thought I'd throw that out there; there's a very good chance that it's steadily overheating, instead of just spiking up like it appears to be...

As far as tips and suggestions, I ended up doing a cooling system flush, replacing the thermostat, and washing the daylights out of the radiator, haven't had a problem since... It was also suggested to me that if the system is not holding pressure, it will overheat, a bad radiator cap can cause this... Or a bubble in the system; trapped air will cause an overheat in no time. Hope some of this helps...
 
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