1991 Cherokee over heating!

[jakeman14]

My girlfriend's 1991 cherokee is still over heating after a coolant flush and thermostat replacement. Also had a radiator pressure test which came out fine. What's the deal?

[JDPascal]

Seeing as it is older than 92, who ever did the flush and t'stat likely didn't get all the air out. Either that or the rad core is plugged internally


JD

[89ltd]

I think you have to remove the temp switch to burp the system.

[Po Pilot]

Not on the 91's. Not a closed system.

Could be the waterpump if it overheats even at highway speeds. If it overheats at idle or in traffic then its the fan clutch gone bad.

[4x4grey88]

If you have to burp the cooling system, loosen the temp probe (in the back of the engine) while the engine is running (not super hot) and the water should seep out after all teh air is expelled.

And just because your test shows that your system holds the correct press does not mean that your radiator is not pariatally plugged. When I had this problem I changed out the water pump, t-stat, flushed it out, burped it and still had to change out the radiator (with a three core open radiator which costed me about $140 delivered. I switched to an open system instead of the closed system in the 1991 and older. I have a 1988). Only after changing out the radiator did my overheating stop.

[badron]

Did you have the cap checked to? Normal that is done with the full system check. But I am unclear on how you had the rad checked. That little cap has fooled more then one pro into replacing a good rad.

[redxj]

Originally Posted by 4x4grey88

If you have to burp the cooling system, loosen the temp probe (in the back of the engine) while the engine is running (not super hot) and the water should seep out after all teh air is expelled.

And just because your test shows that your system holds the correct press does not mean that your radiator is not pariatally plugged. When I had this problem I changed out the water pump, t-stat, flushed it out, burped it and still had to change out the radiator (with a three core open radiator which costed me about $140 delivered. I switched to an open system instead of the closed system in the 1991 and older. I have a 1988). Only after changing out the radiator did my overheating stop.

Hello
Im in the process of converting my 1990 xj closed system to an open sys. but im having a problem with connections for the relay layout that controls the new sensor and switch on the thermo housingand how to do this can you be of any help?