the story of my overheating jeep

Well I've got a 89 xj 4.0 that started overheating. I would drive it around for a little and then the temp would go to about 215 and then coolant would start boiling out of the res. tank. So I replaced the head gasket and the head was pretty warped so I figured it was that. I got it refinished and pressured tested and everything was good until I put it on and it was still running pretty hot. So I got a new res. tank and that solved the boiling over problem and it kept the temp down pretty good but then the temp started heating up after a few weeks. So after what seemed like a frillion hrs of research on here I decided id try the hd fan clutch. It worked very well so I figured I solved my overheating prob. So I bought a lift and started working on other things. Well the first time taking my jeep out after installing my jeep I noticed it was getting a little hot again but didn't quite "overheat". Well I took it out the next day and sure enough it got to about 220 after about an hr or so of driving. It was high speed not crawling either. So today I Changed the water pump. Started it up drove it to the end of my street which is about a 30 second drive and the jeep was already at 220.. is that even possible? From completely cold to 220 in 30 seconds? The only other thing I can think about replacing is the radiator. I took the thermostat out completely just until I figure everything out so its not that. I also wired my efan to a switch so I know its coming on. I thought maybe it was the guage so I tried using a laser thermometer but I'm not quite sure where to point it. I pointed it at the thermostat housing and it read like 170 while the jeeps gauge said 210ish but idk how close the tstat housing temp is to the actual temp. Does anyone have any ideas for me? Or does anyone know where I can measure the temp from with the laser thermometer? Thanks!

I would pull the rad and at very least have it flushed and flow tested. Mine would always run great slow and crawling, a half hour on the highway and it would start to get hot. Your 2nd boilover sounds like just an airlock in the system. fill the coolant though the upper rad hose after then run it until your defrost blows hot. I use a vacuum filler at work, it's very efficient.

Ok--still running the closed system with the pressure bottle?

The OEM and aftermarket caps don't seal very well. Without pressure on the system it will boil at a much lower temperature.

Go buy a Stant 10244 pressure bottle cap. They are off of a 700 series 2.3 L Volvo pressure bottle. They seal better, have a lower profile--won't be hitting the underside of the hood when the bottle expands; and have a slightly higher pressure rating and that will raise the boiling point. Also, the pressure bottle should NOT be more than 1/3 full when cold, that expanded coolant has to have room.

Not a gauge problem if you have boil over.

Also sounds like you have air trapped and need to "burp" the system. Park it nose down, remove the temperature gauge sending unit from the rear of the head, driver's side--be careful not to break it--then add coolant into the pressure bottle until air no longer escapes from the sender port.

Also, run a 30/70 mix ethylene glycol/distilled water. 50/50 is a winter/summer compromise, better as an anti-freeze than a coolant.

Give those things a shot and post back up your results

Alright I will drain the radiator tomorrow and refill with a 30/70 mixture and burp it. I was thinking about getting that volvo cap before but after I got the new bottle it held pressure just fine and has never boiled over since that's why I thought it would be my gauge because it does not boil over anymore just gets way too hot! But I will try all of that and if that doesn't work ill have to get a new rad. Quick question though if I end up having to buy a new rad I might as well switch from the closed system right? But if I do how hard is it? And also thank you guys very much for your help and quick replies!

There is nothing "wrong" with the closed system. In fact, there are plenty of new production vehicles being made every day that are closed.

However, if you want to change--you will need the open radiator, rad cap, recovery bottle, overflow hose. You will have to do some heater/bypass hose plumbing, most just convert to the 91+ coolant control valve for the heater, or eliminate it entirely (some say that puts too much heat in the cabin, others say they don't notice it). That is pretty much all there is to it.

I am quite happy with my closed system. That said, I will probably convert to open when ever I have to replace my current radiator. Simple reason for that is there are a limited number of XJs that were made with the closed system, and many are no longer on the road. As demand drops for the closed radiators, the price will go up and availability will go down--simple economics. There were a lot more XJs made with open systems.

Good luck, post up how it goes.

PS--You should consider doing a 3-6 hour radiator cleaning to see if that helps. The 15 minute flushes aren't very good.

Thanks for the info Joe--I'll be buying the stant 10244 for the 88 eliminator.

you could also try and taking a water hose and spray out the fins of the radiator... i've heard of a few guys going thru mud pits, clogging up their rad's and causing it to over heat. just an idea instead of spending a bunch on money if thats the problem.

Well I burped my system today and took it for a drive and it was perfect. Didn't get hot at all. I drove it hard and in traffic and at highway speeds and it was fine and it was about 95 degrees out today! There must have been a big air pocket in there. Well thanks alot very much for everyones input! Naxja saved another overheating jeep!