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overheating

eightyseven

NAXJA Forum User
Location
Kentucky
I have an 87 Cherokee. I recently had the heater core replaced with a new water pump and thermostat. Unfortunately after it overheats. I've bled the system to get the air out but it doesn't seem to do any good. I am totally perplexed as to why this is happening. If anyone has had this problem before or can offer advice I am all ears. Thanks eightyseven
 
It is possible you have the wrong water pump. The water pump rotation was reversed with the change in belt routing in '96. I am not aware of any external difference on the pumps.

I would expect things to overheat if the pump were trying to flow backwards.
 
I didn't know that so I guess my focus will be on the water pump. How does one know the difference in the water pumps if that turns out to be the problem?
 
I think taking the one you have to the parts store and comparing it with a new one off the shelf that is supposed to be correct is your simplest answer.

In looking for a better answer for you it appears I am incorrect about when the switch in rotation happened. From what I can find it is a matter of when they switched from V-belts to serpentine belts. I am not seeing anything about a change when the belt routing changed in '96.

If what I am reading is correct (it's on the innerweb, it must be true) then all serpentine belt driven XJs use a CCW rotation water pump. Ideally you want to see an "R" stamped on the impeller.

However, manufacturing errors are not unheard of.
 
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