Cooling, thermostat, waterpump
Thread Starter
Junior Member
Joined: Feb 2016
Posts: 49
Likes: 2
Year: 1997
Model: Cherokee
Engine: 4L
Flushed heater core about 6 weeks ago & had heat again. So now I think I have a bad water pump and thermostat. Who can help? Here is the latest.
Went to refill the system after replacement of upper and lower hoses (Gates). Left radiator cap off, started engine, let warm up, then turned on heater, waited for jeep to get up to temperature...after waiting 15-20 minutes the fluid would not drop into the radiator, but started to back out at the cap, call it burp or vomit, but it expelled out where the cap locks down. Things I observed...no heat came thru the vents, inbound line to heater core was not hot to the touch, upper radiator hose was hot, noticed engine block began to smoke, SHUT IT DOWN! Didn't feel the lower hose at the time though may be should have...do I now need to replace thermostat and water pump? Is there more to this?
Going to start with new thermostat, remove water pump and inlet tube to inspect condition.
Went to refill the system after replacement of upper and lower hoses (Gates). Left radiator cap off, started engine, let warm up, then turned on heater, waited for jeep to get up to temperature...after waiting 15-20 minutes the fluid would not drop into the radiator, but started to back out at the cap, call it burp or vomit, but it expelled out where the cap locks down. Things I observed...no heat came thru the vents, inbound line to heater core was not hot to the touch, upper radiator hose was hot, noticed engine block began to smoke, SHUT IT DOWN! Didn't feel the lower hose at the time though may be should have...do I now need to replace thermostat and water pump? Is there more to this?
Going to start with new thermostat, remove water pump and inlet tube to inspect condition.
CF Veteran
Joined: Jul 2013
Posts: 7,554
Likes: 17
From: Monett, MO.
Year: 1999
Model: Cherokee
Engine: 4.0
The heat in the upper and lower hoses is a way to start. Did you do a complete clean and flush of the radiator and engine block till all coming out was clean water?
The radiator may need to be replaced as well if its clogged.
The radiator may need to be replaced as well if its clogged.
Thread Starter
Junior Member
Joined: Feb 2016
Posts: 49
Likes: 2
Year: 1997
Model: Cherokee
Engine: 4L
Haven't flushed radiator and/or engine? What's the best home method to do so? Just a hose? Insert at top of engine block? Would it circulate enough on its own thru the block with just a hose? With engine running? Should I flush those before I put on new parts (thermostat, water pump, radiator)?
CF Veteran

Joined: Jan 2015
Posts: 1,364
Likes: 37
From: Dont Colorado Wyoming
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
disconnect both Rad hoses and flush radiator. Disconnect heater core hoses and heater control valve(if you have one) and flush heater core back and forth.
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Joined: Aug 2011
Posts: 43,971
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0





