I read through this thread a bit and I have found some very interesting thoughts. I see the common thought is that there is insufficient cooling on these little beasties whether stock or not. I have to laugh. There is no way an XJ became popular overnight if this problem occurs on every, or even the majority of these station wagons (after all, that is what they are classified as). Then, add in the fact that some have spent hundreds, even thousands of dollars to make this vehicle even more abusable. Where does that money go? Lifts, lockers, tires, additional weight in the form of bumpers, roof racks, larger spare tires, and larger engines. Guess what? I still say sufficient cooling system.
The common denominator on all these posts is you were using your vehicle in an extreme condition that 99% of the owners of these vehicles DO NOT face, EVER. For us extremists however, we have forgotten the fundamental nature of cooling and how it works. There are 4 things that cool your engine. Air, fuel (cools charge in combustion chamber), coolant, and oil! So you have built your rig to withstand the abuse of climbing a large boulder, or any in succession. Did you upgrade the tires? Did you upgrade the lift? Did you remember to pack a jerry can? You got your massive rock bumper and winch and extra passenger and recovery tools? Ah.. I see you did! Nice. Did you remember to upgrade your motor oil for the conditions? What about transmission fluid? What about the stuff in the pumpkin you might burst later down the trail? Transfer case fluid? Guess not.
I read somewhere earlier someone said that the use of the vehicle was not made for constant 4 LO at 5 mph all day in a blistering 100+ degree day. First off, it was. The way the cooling system works on any vehicle, and the XJ is no different, is to maintain a particular temperature and only fluctuate so many degrees either way. If its not, well you have a PROBLEM! YOUR problem is NOT the problem with the vehicle that every knew about and overlooked, its your problem with your maintenance and planning. Read the manual. For x temperature use x fluid, oil, etc. For x extreme, use other fluid. I have two words for you. Royal Purple. You have spent a thousand dollars to make your rig personal and capable, now give it the tools to tolerate the abuse you put it through. Spend a little extra and get some oil that is designed for that kind of abuse. While you are at it, upgrade all your fluids to synthetic (if available). It has much better heat characteristics and prevents wear on the parts you spent so much to upgrade. ANY and ALL professional off-roaders will tell you that fluids are important, and matching them to your use will only benefit you. Chrysler told you that in your owners manual. Haynes tells you in case the owners manual went missing a few owners ago. And lastly fix YOUR PROBLEM! Cause fluids and radiators and fans and whatever else you can MacGyver into your little beastie is not gonna take care of the massive airbubble in the system from the last time you opened it and didn't do the job right. Hey, we all make mistakes, but don't blame Chrysler, who made the XJ the most popular off-road SUV (**cough, station wagon**) today. Even second-hand this is the vehicle that ALL magazines and owners tell you to get for fun in the back-roads. Maintain it and be on your merry way already. BTW, I have a cooling problem. I have a massive airbubble in my radiator (sealed system) and almost no oil in the oil pan. Any ideas? Oh yeah, I leaked a gallon of antifreeze on my neighbors cat that had huddled underneath my headgasket. LOL Good luck and the only thing that should break is the pieces that hit the rocks.
