Fired up the XJ this morning to let it warm up before taking off. Went in the house for about 10 minutes, came back out and it was pouring coolant down the front. I immediately shut it off and popped the hood up to see where it was leaking from. It was coming from my radiator cap, no hairline cracks in the plastic that I could see but man did it spew coolant. So needless to say the XJ was parked back in the barn for the day. So what could my problem be? I think it was leaking coolant yesterday too, i pulled into a parking lot and parked, once i got out i saw a drip trail from where I had drove in yet my XJ does not leak when it is shut off. So i have a few ideas, the radiator cap could not be getting a good seal, maybe the water pump is bad?? Where should I start first? I got a picture (yeah it isn't the best) but it kinda shows what I am up against. My coolant level in the overfill bottle has dropped significantly. I believe it is a reoccurring problem, the previous owner mentioned that it would leak coolant sometimes and believed there was a hairline crack somewhere but didn't know where.

 

Gotta flashlight?......time to get dirty. Don't be like the PO......find it, fix it. On any 20 year old vehicle, hood's gotta be opened often and things checked frequently.

 

Thats the plan. I check the fluids on the XJ every few days, yesterday the fluids were in perfect order, nothing was low... Just picked up the XJ and drove it to town (got more tools to work with here). No over heating issues, I did top it off with water before leaving. I know some truck drivers and have been getting some advice from them. They said check the fan clutch for resistance after the engine is hot. That checked out okay, still some resistance. So that should narrow it down to the radiator, water pump or temp. sensor. We will see....

 

U need to find/fix your coolant leak(s) asap. Until the leak is repaired, u need to be adding properly mixed coolant/antifreeze, not water. The so called fan clutch "spin test" is bad/unreliable advice. Unless the PO left a reciept in the glove box indicating a recently replaced fan clutch.....buy a new one, it's a $35 part. <$250 buys a new cooling system including a new rad.

 

get a new, better cap, mine leaked all the time, replaced the factory cap, not a drip! also get the caps that have the locks on them, i replaced it the 1st time with a generic radiator cap and it still leaked, get the high pressure ones

 

Thanks again guys for the advice! I have been looking for answers on the internet as well as on the XJ. The larger lines coming from the radiator are warm so coolant is passing through them. It seems that I only have this problem when the jeep is at idle, it doesn't come close to over heating at speeds over 30 mph. I also started it up and let it run at idle and both fans run so i assume that the fan clutch is working. I checked the fluids again, still in good shape there, good on oil (it is filed every so often due to a leaky valve cover gasket), and coolant levels are a little lower than when I left home (either leaked out or some air was purged from the system). I can easily go pick up a new radiator cap but since it is not leaking now i am not sure if that is the issue.

 

Git 'er done.

 

Thanks for the advice. I will run down and get myself a new cap. You are correct, it gets hot when at idle, I shut it off before it reached 240. I drove it 10 miles today at highway speeds and the temp stayed bellow 210*F.

Just a side note, my XJ just turned 188K miles yesterday.

 

If u start some serious TLC asap (and quit listening to your truck driver friends about fan clutches) u may get another 188K out of it. A few more times at 240F and it'll likely be parked.

"If it ain't broke, don't fix it" absolutely/positively does NOT apply to the cooling system.

 

So long as Djb agrees, I'd second a new cap. It shouldn't leak there. Excessive pressure should go to the recovery thank, then be drawn back when the engine cools. Running day in, day out like that might result in low coolant and overheating. Your cap should never leak. I have a different "time bomb" system. We are happy when it's just the cap.

Myself, if I wasn't worried about a freeze, and had added a bunch of water, I might just run it on whatever till the leak is solved, then flush and go with 50/50. I don't lnow what you lost or what you added, but my last problem ended with a drain and refill with a fresh mix.

 

Well, I made a sad discovery. My radiator has crud built up in it (someone used stop leak in it at one time). I also discovered a plastic joint above the oil filter also leaks a little, but just drips, nothing huge there. So here is here i am now.. I have a new radiator as well as a new radiator cap. Before I do anything I will have a certified mechanic check it out to be sure this is my problem, worst case I have an extra radiator which i could use later on (it was $114). So that is where I am at now, I have a couple small things I plan to change as well (like the plastic joint, the oil pressure sensor, possibly the battery cables). Wish me luck guys!

 

Most likely "the crud" in the rad is from years of cooling system neglect.....i.e., little to no corrosion protection, (running mostly water) in a cast iron motor, will cause sever internal rust and deposits in the entire cooling system, not just the radiator.

 

Well, I am feeling kinda stupid right now.. I was looking at it and I noticed that the small cable with the rubber boot on the end was not connected to the heater valve. So basically my valve was stuck closed. The valve itself had a hairline crack and leaked coolant a little but not a lot. I drove to the local auto shop here in my small town and they said try replacing that and see what happens. So a short trip back to Napa again I picked up a new heater valve ($18.99) and an oil pressure sender ($40) (the gauge has been erratic for years). Quick install of the two and i fired up the XJ for a test. I wanted to replicate what happened yesterday morning where it idled for 10 minutes and began to over heat. Today, ran great for 10 minutes, temp. stayed at 200 and did not climb any higher, oh and the oil pressure gauge works well too. So I think this may have solved the problem. I am already kicking myself about the new radiator but I will keep my eye on that, the old one does have some crud in it. For now though, it's looking good. Thanks guys for all the help, I really appreciate it!