djb383

Did it overheat before or after all the new parts? As much driving as u've done, "burping" is a non-issue, presuming the rad cap is functioning correctly AND u r positive there r no leaks anywhere in the cooling system. Did u install a new rad cap?.....it's critical to the proper function of your "open" type coolant recovery system. It still sounds like air is re-entering the system each time the motor cools.....not good. When the motor is COLD, coolant should always be at the very top of the rad and the bottle about 1/3 full. Never allow the bottle to get empty.....if it does, u can bet money air is in the cooling system.

A new pump is going to be good but one way to test the water pump is...disconnect the larger heater hose at the HCV, have someone start the motor. Have a good grip on that heater hose and be very careful where u point the hose because the moment the motor starts, that heater hose will turn into a fire hose...lots of coolant gushing out quickly. Obviously u will want to turn the motor off after a second or two of coolant squirting everywhere. Since u've replaced the water pump, just call it good and don't spray good coolant everywhere. LOL

Have u considered eliminating the HCV?....the factory did on '97 up XJs. Lots of folks have eliminated it vs replacing it. With it gone.....one less part to malfunction, one less place to leak. Something tells me that with the HCV gone, your heat will be back to normal.

'90Cherokee

Heater control valves are designed to default to full heat if the vacuum is lost so unless the spring in it broke it would be open and flowing hot coolant until a vacuum source closes it.

djb383

Good call......makes sense. Sounds like spring is another failure waiting to happen.........but not if it wasn't there.

DirtWaterAltitude

It was the heater control valve. Thanks djb383! I bypassed it and it is working great.