kansas_jeeping

So I've got a 1987 XJ that I've owned for about 4 months now. At about the 3 month mark it seemed that it was running hot (around 230-240*) and so I decided I'd replace the thermostat. When I went to change the thermostat I did not drain any of the original coolant (looking back that would have been a good thing to do) and when I took the thermostat housing off to get to the actual thermostat I expected coolant to leak all over. Not the case. Nothing leaked out and there was only a small amount of coolant visible after removing the thermostat. Question 1: Is this normal? I continued with the replacement according to my Haynes repair manual. After installing the new thermostat (not sure on what temp it was rated) and refilling the coolant to the specified level in the manual, I ran the Jeep and it was running at low temps even after an hour of driving, I'm talking 160* or so and it never got above that regardless of what was going on. Question 2: What is the average operating temperature for a 1987 4.0L XJ? I figured 160* was excellent and it's been running at that temp consistently until about a week ago. It has been moving around from 160* to 230*, and moves quickly. I've noticed that if I'm sitting at idle the temp goes up pretty rapidly. During acceleration it'll drop back down to 160-170* range and hang out there at highway speeds (uphill, downhill has no change on temp), but as soon as I start slowing down it starts to go back up. I've also noticed that now when I park the Jeep after completing my drive it starts to smoke out of the front passenger side, and coolant dribbles onto the pavement. I looked into this and found that the radiator connection tubes seem to be the issue. I can park the Jeep and keep it running and notice that occassionally a small amount of coolant will spurt out of one of the connections. Assumedly it's landing on something hot and burning off causing the smoke. Question 3: Any suggestions on replacements for the connections, or how to seal up that leak?

Thanks in advance for any insight into my situation.

Throttle Jockey

first off, you gotta fix the leaks. second, sounds like a 160 t-stat. third, you may need to burp the system. the temp sensor will only read accuratly when it is submerged in coolant. if you have air in the system, it will make your guage readings go up and down.

troy fritz

2xs that. Your coolant sounds like its coming out of the overflow bottle. Burp it. Run it to temp then turn it off and turn cap slightly to let the air out . Then repeat until no air. Careful not to turn too much so the cap dont pop off and wear a glove or use a rag.

kansas_jeeping

Any suggestions on how to go about this? Radiator stop leak? How do I stop the leaks in the connecting hoses to the radiator? Are there replacements available? Perhaps I am using the wrong terminology and so my searching online is useless. Thanks for the assistance!

troy fritz

Check to see if the fluid is coming out of the overflow bottle. Its on the passenger side where you said it was leaking. If thats the case then you dont have to fix any leaks cuz you dont have any. If you have air in the system then that could cause it to leak . Try burping it as mentioned earlier. Mine did this after I replaced the rad and I burped it and its fine now.

kansas_jeeping

It's not coming from the bottle. It's coming from the metal piping connections that stem off of the radiator.

alpine.adrenaline

When you leave even a little air in your system the pressure pushes out coolant. As you system cools when you shut your engine off, the pressure drops and it sucks in air. Drill a hole in your thermostat (https://www.cherokeeforum.com/f2/pho...d-holes-25710/) and if you can't get those leaks to quit replace your radiator.

kansas_jeeping

"Burped" the system and was amazed to find that I was able to add an entire jug of coolant. Running much cooler now.