88 Cherokee Cooling System

[stevewar]

My 88 Cherokee has always run hot, but last weekend the temp sky rocketed to about 260-270 degrees. I determined that the Thermostat was not opening as it should so I replaced it. It ran fine for a couple of days (around 220 degrees) but now the problem has surfaced again. It seems as though the coolant is not reaching the thermostat. The larger hose from the radiator to the engine seems to remain empty. I am curious what the problem could be. A tell tale sighn that it is not working right aside from the quick, steady increase in temp) is that there is no heat available. The other day I risked driving it around the block-I had no heat and the temp went through the rough (overflow tank was just that-overflowing) Then the heat kicked on-the temp maintained for about 2 minutes and then it returned back to no heat and the temp on the rise. Could this be the waterpump? Should I try pulling the new thermostat out? Please help with any tips. I would love to save this almost antique

[cherokee_guy82]

I can understand your concern because I have a '92 Cherokee Laredo, and would hate for any thing to happen to it. Start the engine and squeeze the top hose shut after the thermostat heats enough to open and see if you can feel the pressure build and rush out as you let go, if you can't, it is the water pump and that would be my guess as to being your problem... cooling problems are usually not very complicated. the other clue is that you have no heat, meaning that the hot water is most likely not reaching the heater core, and worse, the radiator... just be sure that it has not overheated or you will have even more complicated problems later. a simple way to tell is water droplets on the oil dipstick or excessive water in the exaust

[jeeper61]

pre-92 cherokee heating problems are never simple unless you have converted to an open system. read this thread and follow the instructions in the last post for a permenant fix

http://www.automotiveforums.com/vbul...d.php?t=283017

[tonsoffuns]

you could have to get a new waterpump, radeator could be pluged, or you could have a craked head. for a cracked head get a compretion test.

[Saudade]

As Jeeper61 says, the closed system in the pre-92 are a bear to fill. I have an 88 as well. Problem most likely is you have trapped air in the system. Search this forum for "trapped air" or "overheating" and you'll find tons of stuff.

[chili]

Originally Posted by Saudade

As Jeeper61 says, the closed system in the pre-92 are a bear to fill. I have an 88 as well. Problem most likely is you have trapped air in the system. Search this forum for "trapped air" or "overheating" and you'll find tons of stuff.

I feel your pain had similar problems on my 90. The trick is that you need to burp the system......park the jeep on a hill with the nose lower than the rear end and look at the drivers side of the motor near the fire wall....you need to carefully remove the brass temp gauge (13mm i think) to allow the air to escape from the block.....get the engine up to temp....let it cool and remove that valve CAREFULLY.....loosen it till finger tight then hold on tight and lift it up carefully.....you'll hear the air escape......reinstall the sensor run the jeep back to temp....let it cool again and repeat till all the air is gone.......

Good luck

[dima4855]

I would say it's the water pump. Especially if it happened all of the sudden.

dima4855