Overheating
Thread Starter
CF Veteran
Joined: Dec 2010
Posts: 2,366
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From: Spanish Fork, Utah
Year: 1989
Model: Cherokee
Engine: Renix 4.0L
I have an 89 cherokee. My jeep was having bad issues with getting hot. and blowing the pressure bottle cap off. well i figured the bottle was cracked and leaking so i was done with it. i got a 94 cherokee radiator and swapped it in, and it all went smoothly. but its still getting really hot.
my question is, could it be the thermostat to blame? none of the heater hoses or radiator hose, or even the coolant in the radiator gets hot, but the coolant temp guage reads... over 210 and climbing.
Could the thermostat be stuck shut, and it's not letting coolant flow? that's why the radiator and hoses stay cold, but the engine gets so warm?
any input is greatly appreciated.
my question is, could it be the thermostat to blame? none of the heater hoses or radiator hose, or even the coolant in the radiator gets hot, but the coolant temp guage reads... over 210 and climbing.
Could the thermostat be stuck shut, and it's not letting coolant flow? that's why the radiator and hoses stay cold, but the engine gets so warm?
any input is greatly appreciated.
Junior Member

Joined: Nov 2009
Posts: 70
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From: mcminnville TN.
Year: 1992
Model: Cherokee
Engine: 4.0
If your thermostat is stuck your hose going from the water pump to the radiator will stay cool. Also you can turn your heater on and the air will only be warm.
Thread Starter
CF Veteran
Joined: Dec 2010
Posts: 2,366
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From: Spanish Fork, Utah
Year: 1989
Model: Cherokee
Engine: Renix 4.0L
Yes the hose was cool. I didn't feel the air from the heater, i'll check that.
But does it seem probable that my thermostat is stuck?
But does it seem probable that my thermostat is stuck?
Member
Joined: Jan 2010
Posts: 139
Likes: 1
From: Eagle County, Colorado
Year: 1996
Model: Cherokee
Engine: 4.0L I6
I had roughly the same problem, once upon a time. I was on the trail and noticed steam coming from under the hood. I stopped, checked the radiator and hoses, looked around and noticed that my coolant overflow hose wasn't connected well to my radiator. I found a small hose clamp, cleaned that little area up and put it all back on. It did fine for a week. I was in Moab and it started running hot on the trail, but my heater still was only warm. It then hit me: I still had my OEM radiator cap. I went and bought another cap and it has been fine ever since. I still need to swap out my thermostat, but I almost never hit 210 degrees, even on a really warm day (which around here is 80 degrees).
Thread Starter
CF Veteran
Joined: Dec 2010
Posts: 2,366
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From: Spanish Fork, Utah
Year: 1989
Model: Cherokee
Engine: Renix 4.0L
the cap and radiator are brand new, like a half hour old. and it still gets way hot. one heater hose is really hot, but the rest are cool. and the heater isn't blowing hot air,... just warm.
Junior Member

Joined: Nov 2009
Posts: 70
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From: mcminnville TN.
Year: 1992
Model: Cherokee
Engine: 4.0
If your radiator and your coolant tank is full then I would say that could be the culprit. It looks like your not getting any circulation. Once it heats up and the hoses are hard to compress it should be your thermostat. Usually if it is a water pump issue it will leak fluid or if it is just weak it will cool somewhat especially while driving it or giving it gas you will see the temp drop and the hoses are not air tight.
Thread Starter
CF Veteran
Joined: Dec 2010
Posts: 2,366
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From: Spanish Fork, Utah
Year: 1989
Model: Cherokee
Engine: Renix 4.0L
If your radiator and your coolant tank is full then I would say that could be the culprit. It looks like your not getting any circulation. Once it heats up and the hoses are hard to compress it should be your thermostat. Usually if it is a water pump issue it will leak fluid or if it is just weak it will cool somewhat especially while driving it or giving it gas you will see the temp drop and the hoses are not air tight.
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CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
It sure would be easy, while the t-stat cover is off and coolant is drained, to replace the water pump and fan clutch. U've done 2 of the 4 major cooling system components, why not git 'er all done and eliminate the guessing.
Last edited by djb383; Jul 1, 2011 at 02:26 PM.
Thread Starter
CF Veteran
Joined: Dec 2010
Posts: 2,366
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From: Spanish Fork, Utah
Year: 1989
Model: Cherokee
Engine: Renix 4.0L
Originally Posted by djb383
It sure would be easy, while the t-stat cover is off and coolant is drained, to replace the water pump and fan clutch. U've done 2 of the 4 major cooling system components, why not git 'er all done and eliminate the guessing.
Member
Joined: Jan 2010
Posts: 139
Likes: 1
From: Eagle County, Colorado
Year: 1996
Model: Cherokee
Engine: 4.0L I6
Great point. If for any reason I need to pull my transmission, I always do the clutch, unless it's been under 10k miles. You might as well while you're down there.
CF Veteran
Joined: Nov 2009
Posts: 8,172
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From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Great idea on replacing the clutch when the tranny is dropped.
With both the t-stat cover and water pump removed, u'll be amazed at the crud/crap that can be flushed when u stick a garden hose in the t-stat hole in the head.
With both the t-stat cover and water pump removed, u'll be amazed at the crud/crap that can be flushed when u stick a garden hose in the t-stat hole in the head.
Thread Starter
CF Veteran
Joined: Dec 2010
Posts: 2,366
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From: Spanish Fork, Utah
Year: 1989
Model: Cherokee
Engine: Renix 4.0L
Originally Posted by djb383
Great idea on replacing the clutch when the tranny is dropped.
With both the t-stat cover and water pump removed, u'll be amazed at the crud/crap that can be flushed when u stick a garden hose in the t-stat hole in the head.
With both the t-stat cover and water pump removed, u'll be amazed at the crud/crap that can be flushed when u stick a garden hose in the t-stat hole in the head.
Senior Member
Joined: Jan 2011
Posts: 689
Likes: 2
From: Upstate N.Y
Year: 2000.1999,1996
Model: Cherokee
Engine: 4.0
Why dont you first check to see if you have air in your system,everyone here has seemed to forget to check the simple things first and want you to throw money at it first.(duh)


