kornellred

Courtesy of my son, I now own a 1988 Cherokee with the 4.0L in-line 6 cylinder engine, auto trans, 4WD. 150,000 miles. It looks good and runs strong.
The pressurized coolant tank split on the top near that little nub thingy that sticks up in the middle of the rubber strap. A replacement is on order and should arrive soon. I have no idea how much coolant boiled out of the system. What I do know is that within 5 minutes of starting the engine, whatever is in the system boils violently.

For someone unfamiliar with the in-line 6, a look under the hood can be quite intimidating. How do I check the coolant level when I install the replacement tank? Does the temperature sensor in the radiator control the operation of the electric fan? The belt driven fan blade is always turning at what I assume is engine RPM, but since it is equipped with a viscous clutch, is it supposed to?

I would really appreciate a short tutorial on the cooling system problems in the early Cherokees, or perhaps someone could point me in a direction where I can get my questions answered.

Willie R.

Abovetimberline

Cherokees up to 90 had the cooling system you have they are a problem. I changed mine over to a newer style that came out in 91 when chrysler took over. When you replace the bottle you will need to burp the system,there are a few ways to do this. I have always just let it warm up and cool down,once bottle is empty just add more water and repeat until temp is good and water level in bottle remain the same,I think there is better ways though. Do a search on here about burping them,the system I have now does not need to be burped.
The sensor on the radiator does control the fan and the one on the head next to the firewall is for the guage.
The mechanical fan will turn at what appears to be engine speed,to check it turn it by hand when cold and again after it warms up,it should be a little stiffer when warmed up.
I always carried a new bottle everywhere I went that is how much I trusted the system.
One thing not to do is overtighten the cap or take it off and replace it when it is hot,you will strip the threads.

xjrev10

might be a good time to flush all the coolant out of the system and replace with new. your jeep should hold about 2 gallons. Someone correct if wrong.

rivercrazy

If your system is boiling after 5 min you've got a problem. Either the coolant isn't circulating or there's not enought air going through the radiator. If your fans working ok its probably your thermostat or your water pump.

Thermostats are cheap so I would replace that first and fill the fluid. If that doesn't work its prob the water pump.

BlueXJ

System burp is easy. Put the rear wheels on ramps. Drivers side of the rear portion of the head is the temp sender. Using a deep socket remove it. Just fill that replacement tank until coolant starts to come out of the sender void. Replace the sender using pipe dope. Drive Jeep off of the ramps and there is a small elevated section in the bottom of that new tank. Coolant should be slightly above that "chair". That is what the elevated part is called. Burping is completed.