Well, about a month ago I looked under the hood and my coolant reservoir was empty, the engine hadn't been running hot, and the actual radiator was full, so I shrugged it off and filled up the reservoir and went on my way. Well I checked it about two weeks later and it was empty again, and I finally checked it again, about two weeks later, and it was empty.

The engine hasn't been running hot, a friend seems to think there may be a leak in the heater core, but I don't know anything about cars enough to tell whether or not that's the case. I also read somewhere that a small leak may be a sign of a blown head gasket, but the coolant/oil isn't milky, so I don't think (and hope) that isn't the case.


Does anyone have any clue as to where my leak might be? It's just strange to me at how slow it is, and how my engine hasn't been running hot.

 

If you're having to add coolant to the reservoir, you're either leaking it or burning it. Your job is to find out which. If you haven't seen any increase in the temperature on the coolant temp gauge on your dash and if your engine has never overheated, I'm leaning more towards a leak, rather than an internal problem like a headgasket.

First, get underneath your XJ and with a good light, perform a thorough inspection. Pay special attention to the plastic seams on the radiator and also the weep hole on the water pump.

Is this the original radiator? How about the water pump? If your radiator is original, there is a very high probability that it is the source of your leaks. The cooling system parts don't last forever. OEM radiators with plastic seams almost always start leaking from the seams. Also be sure to check all hoses and also the frost plugs on the engine.

If you end up finding a bad radiator, replace the water pump while you are at it unless that has been done before. As well as a new thermostat and hoses, etc. The money you spend on cooling system maintenance is possibly the best money you'll ever spend on your XJ.

If you get stuck and can't find the source, take it into a trusted shop and ask them to perform a "cooling system pressure test". That would be the first diagnostic that a technician would take (after inspection) to try to find the root cause here.

Good luck and keep us updated.

 

I appreciate the thorough response. I'll get under the hood this weekend. Everything is all stock, and it just came up around 126000 miles.

 

Check and see if the carpet feels damp on the passenger side. Also if the heater core is leaking you will almost every time have a sweet smell from the coolant and sometimes the windshield will fog up while driving. Also if only the overflow bottle is empty and not the radiator make sure that you don't have any cracks in it. With a little luck it will be something minor. Let us know what you find.

 

After hopping out of my car today I smelled coolant, popped the hood and finally found the leak. It seems to have gotten bigger, as I could actively see it dripping from the neck of the radiator. With that being said, I'm going to goo ahead and replace the complete cooling system (water pump, hoses, etc.). This is just a daily driver vehicle, so I don't need crazy performance parts, but I would like something that offers something more than the OEM does. Does anyone have any reccomendations on specific parts (I'm new to the self mechanic thing, and don't know exactly where I should be looking)? Also what should I expect to pay for everything once totaled together?

 

For these cooling systems, OEM is actually quite good. It's lasted 14 years without maintenance, so an overhaul should last you quite some time again.

When I replaced everything in my Comanche, I got a new radiator from CarQuest. It isn't all-metal like the ones from CSF that some people swear by, but it's 1/3 the cost, has the fittings brazed on, and I can easily warranty it if there's a problem.

I also replaced the water pump, heater control valve, thermostat (buy a Mopar t-stat from the dealership), thermostat housing, overflow bottle (probably not necessary), and all the cooling hoses under the hood.

If you ever have the engine out for any reason, or you remove the intake and exhaust manifolds for any reason, replace your freeze plugs. I wouldn't go through the hassle now if they aren't leaking, but you'll want to put in new ones if they're ever readily accessible during one of you projects.

When you decided to go through with the overhaul, backflush your cooling system before you remove anything. Backflushing gets all the crap out of the motor, but you don't want it to end up in your newly installed components. Backflush, then replace everything.

 

The heater bypass valve is one of the most commonplaces for a leak on xjs

 

This is the way to go. I picked up my radiator from autozone for under $100 and haven't had a single problem and that was over 4 years ago. The best part of it is if I do ever have a problem with it I don't have to wait if it was ordered. BTW, since you have a 99 you don't have to worry about a heater control valve since you don't have one. Keep us updated on how your project goes.

 

Good catch. I forgot about that change. My '01 never had cooling problems, and I converted my '88 Comanche to a '91-style (open) cooling system which still used a HCV.

 

I appreciate the quick responses, this forum has been a lot of help. I'd like to run my list by yall to see if I should change anything/add anything for doing this repair. All of these parts are from Car Quest:

Car Quest Radiator (Part # CU1193)
Car Quest Premium Serpentine Belt (# K060895)
CQ Premium Rad Upper Hose (#23283)
CQ Premium Rad Lower Hose (#21615)
CQ New Water Pump (#51-3111)
CQ Rad Cap (#33042)
CQ Premium T Stat 195* (#60209)




The water pump on my list is priced significantly higher, $70, compared to the other ones.

http://www.carquest.com/webapp/wcs/s...9029?acesApp=1

Any particular reason why that would be, and should I go with the cheaper ones?



I was convinced to go back the stock route, because it is just a daily driver, and the stock system has lasted long enough as is.

 

Just for some closure, I just done doing the work. Everything went in without a hiccup (that is definitely a first), decided to go with the forum consent and not use the CQ thermostat and just left the one that was in there alone.

 

just out of curiosity, I am losing a little coolant also, a few drops here and there and sometimes a small grapefruit sized puddle when I get home after work.

When I look under the Cherokee I see what looks like it is losing coolant from the water pump but I can't see the weep hole on it. Is it visible without too much trouble and I have been looking in the wrong place?

Also, what was the total on this cooling system swap out for new stock parts? I have a 98 Cherokee