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Over heating...4.0 in 97 cherokee


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Been having over heating issues with my jeep. started over the winter but wasn't really an issue due to the cold helping me out. I knew both fans were toast so I replaced them and still have issues.

 

Last summer I did the radiator and water pump and thermostat.

 

I am thinking that I might have a bad thermostat.

 

Here is what it's doing, heats up to 210 avg the fan clicks on which is good but temp continues to climb. its been doing this for awhile and some times if I blip the throttle the temp will drop back to normal.

 

Thoughts?

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1) Are you sure the aux fan is activating? The one in my wife's 2000 XJ is seized up solid, and it was overheating at the end of the summer. Now that Spring is here I need to install the replacement that's riding around still in the box behind the seat.

 

2) Are you certain there are no air pockets, and that the system is filled?

 

3) Are you certain you got the correct water pump? The 4.0L with the serpentine belt uses a reverse rotation (compared to the older engines with multiple vee belts) water pump. The housing and bolt pattern are the same. If you got a water pump for a 4.2L with vee belts, it ain't pushin' any coolant, and that's not a good thing.

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Does the temp gauge start creeping up and then when it hits a certain point it will instantly peg to the right and your "check gauges" light comes on? If so, that's just the way the 97+ XJs were designed and doesn't necessarily mean you've "pegged" your gauge - just a safeguard. I had this issue in a '01XJ and replaced all of the things you mentioned and it still didn't help. Turned out that the engine block was full of coolant crud/mud/rust/crap that was blocking coolant flow.

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1) Are you sure the aux fan is activating? The one in my wife's 2000 XJ is seized up solid, and it was overheating at the end of the summer. Now that Spring is here I need to install the replacement that's riding around still in the box behind the seat.

 

2) Are you certain there are no air pockets, and that the system is filled?

 

3) Are you certain you got the correct water pump? The 4.0L with the serpentine belt uses a reverse rotation (compared to the older engines with multiple vee belts) water pump. The housing and bolt pattern are the same. If you got a water pump for a 4.2L with vee belts, it ain't pushin' any coolant, and that's not a good thing.

 

 

yes yes and yes I did the rad and water pump maybe ten thousand miles ago and only started having issues over the winter. I will check the belt routing though as I recently had it off to do the fan clutch.

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Does the temp gauge start creeping up and then when it hits a certain point it will instantly peg to the right and your "check gauges" light comes on? If so, that's just the way the 97+ XJs were designed and doesn't necessarily mean you've "pegged" your gauge - just a safeguard. I had this issue in a '01XJ and replaced all of the things you mentioned and it still didn't help. Turned out that the engine block was full of coolant crud/mud/rust/crap that was blocking coolant flow.

 

Interesting....that is what is doing. It needed the fans because both broke (clutch bearing went on the manual and electric motor fried on the other.it was driving fine before though so I hope its just the thermostat.

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