A/C is part of the defrost system, dry air defrosts better. If your a/c doesn't work it's just outside air being blasted onto the windshield. If the a/c doesn't work your electric fan won't either, i have this same problem on my 98. After shutting off the engine the reservoir fills up with boiling coolant, usually its not bad but sometimes it can leak out and make a nasty mess. If the OP's e-fan is working though i'm not sure why this is happening. Perhaps you should look into the mod that wires the electric fan into the headlight timer delay, this would give it a little extra cooling after the ignition is turned off

 

if i am wheeling and i shut it off after working it hard it'll boil but if i let it idle, and the e fan is running, till the fan shuts off then i am fine gotta upgrade to an open system!

 

^not normal

 

I think the question is, exactly what does the OP mean by "boiling". What is the system doing? Is steaming, bubbling coolant pouring out of the system?

Bubbling into the recovery bottle after engine shutdown is not necessarily boiling.

 

Guess our '98 is different from others.....When we remove the a/c clutch fuse, the a/c compressor is totally disabled however, the rad efan will still turn on in any of the vent selector positions where the compressor would normally be engaged.

Cold dry air, like when the compressor is engaged, will defog the inside of the windshield, not defrost the outside of the windshield. Defrosting the outside of the windshield only occurs when air off the heater core is directed to the windshield and becomes hot enough to overcome the cold air off the evaporator (compressor engaged) that is also directed at the windshield.

 

My 2000 XJ is doing pretty much the same thing. It never overheats but when I drive it for 10 minutes or more it drips coolant from the front passenger side. I have replaced the t-stat and also water pump because originally my inlet tube was ate up and I had to pull the pump anyway. I was positive that the inlet tube was the culprit but it's still doing it. I noticed that my e-fan wasn't working also so I tried to jumper it and it still wouldn't run. After replacing it, it still doesn't come on no matter what I do with the A/C or defrost switches. Maybe it is low on freon because it cycles on and off very quickly (couple seconds). I think I'll try pulling the A/C clutch fuse to see if that works.

Could it be that I installed a 180 degree thermostat and it just never gets hot enough for the fan to come on?

 

Now tonight she ran under 210 and at idle for a while, maybe it was just the sound of it going back into the reservoir tank, my friend used to work for jeep so I'll have him check it out while its in getting other work done. Thanks for all the help I'll keep ya's posted

 

If your dripping coolent...then you have a hole that is also letting air into your system.

 

Very well could be......our efan is never on during the winter months (unless the compressor is engaged). We run a 180 t-stat as well. Fan "on" temp is 218F. The efan should turn on (default) when the connector at the t-stat cover is unplugged.

 

ok, maybe that's part of my problem. can there still be air in it if you open the cap the day after you fill the system and the coolant is right at the top? I'm chasing an overheat condition on extended highway trips. once it gets hot after 100 miles or so, it's prone to overheat pretty quick. it got a new 2 row aluminum radiator, and has all new hoses, pump, tstat, cap and coolant.

 

Yeah, just because you see coolent at the top, doesn't mean its full.. look up how much coolent your supposed go have in there. Fill with that amount, you have to fill while running when the t stat is open and heater on full blast. Add more after. Add more to the overflow tank as well.

 

If the rad is full to the top the next day (after several heat/cool cycles) AND the recovery bottle always has coolant in it (motor cold or hot), then it's burped - no more air in the system. Coolant level should rise a little in the bottle (hot motor) and fall a little (cold motor) but the bottle must always have some coolant in it. The radiator cap is the key to the coolant recovery system.....there's 2 valves in the rad cap and both must function correctly.

 

As I stated, it "sounds" like it's boiling, it's not overheating and not dripping anywhere that I can see

 

It doesn't overheat and it's not dripping from anywhere that I can see

 

If u have a leak somewhere (maybe small/unnoticeable), air will enter the cooling system when the motor cools. When the motor heats up, that boiling or possibly "bubbling" sound could be the air that has entered the system is now escaping the system into the recovery bottle.