88jee

Hey All!

I have been having so many overheating issues with this car!! Its an '88 jeep cherokee pioneer.

I replaced tstat, water pump, expansion tank cap because the car was overeheating on the highway originally. I have been driving around for about a week and the coolant temp was staying where it should, got up to 190 and then the tstat opens and it was holding there.I bought it at Napa, standard 195 tstat. The temperature coolant sensor was a little rounded and corroded so I decided to replace that as well. When I took the sensor off, I lost about a quart coolant out of the outlet where the sensor goes but I filled it back in the expansion tank. After I had put on the new coolant temp sensor, I was driving out and the tstat never kicked on, I watched the gauge move past 190 and got to 240 before I cut the car off and felt the upper radiator hose, it was cool to the touch no coolant from the engine went through there and the tstat never opened. I am pretty sure the tstat was not installed upside down, I had been driving about a week with the new one on and everytime it has opened at 190. The other thing that was kind of odd was that the expansion tank had no pressure in it. Usually when the car is that hot, some hot air will come out and I will usually get some hot coolant coming out. Nothing happened. I have no clue what to do next! Any help is greatly appreciated, thank you so much for all of your help!

jakbob

You have air in your coolant system. Time to burp it.

Also, thermostats dont turn on, they open/close and do not control maximum temp, but control minimum temperature. If you are overheating while driving, check your waterpump (see how well the heat works when is driving, if it is cool, its the water pump), and radiator.

88jee

I have heard many ways to "burp" this system, what is the best way? Yes heater is working fine so i believe water pump is working fine. Thanks for the help!