HELP find my missing coolant!!

I've got an '01 stock XJ. Had it for 4 years now, runs great, my everyday driver. I do standard maintenance but not all that regularly.

Anyway, my coolant continues to disappear. Not sure where it's going. No big puddles under the jeep (more to this I'll get to in a min), no sign of the head cracking (other than the lost coolant), power is fine. What could it be?

The one puddle I do consistently get under the jeep is almost under my heater core. I'm wondering if this is the culprit. However the water comes from what looks like a line stubbed out just above my oil filter. Not sure what this line is for but it bleeds out moisture. Any idea what this stubbed line is or where my coolant is going?

Coolant loss is about the amount of overflow tank every month.

Here's a pic of the stubbed line.

http://uploads.tapatalk-cdn.com/2016...e5347aba95.jpghttp://uploads.tapatalk-cdn.com/2016...8b0c6782ef.jpg

I did replace radiator & hoses/flush system earlier this year, maybe April or so. All of the connections are secure, no leaks.

I found your missing coolant. It's in my driveway.
But seriously, did you try replacing the radiator cap?


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Ha! Well finders keepers!

I did replace the cap as well. No signs it's coming out there, I even pressure checked the cap & it appears to be working at correct psi

That little line is your condensate drain for your AC core. But the question remains, is that puddle just water or is it green?

Sure looks like water, no green whatsoever, doesn't taste sweet or like antifreeze.

As the engine coolant heats up it expands and flows to the overflow. When it cools it sucks it back from the overflow. Over time the overflow can get near empty, lots of time and I suspect how humid the air is.

If the coolant gets too hot it will put too much coolant in the overflow and it will empty on the ground while driving, then again the remaining overflow contents gets sucked back into the cooling system.

It could be that your cooling system is dumping while your driving or sitting still in like at Jack in the Box.

New radiator cap is an excellent idea. How hot is the coolant temp getting during driving?

I recently checked the coolant while engine was up to operating temp, after a 1.5 hour highway driving trip. The tank was not empty but well below the fill line. If I were to have not filled it, eventually the tank runs dry. I don't, try not to, allow this to happen & consistently watch it, adding coolant once a month or 45 days. I'm just clueless as to where it's going. I'm thinking maybe a hairline fracture in the header, isn't this this weak header design? From the '01s? A few months ago a friend talked me into doing the seafoam trick thru the vacuum line. Well it smoked like a chimney, & even some from around the header. Not a lot there but some. Could this be a sign of a small crack there? How can you diagnose a cracked head? Any pressure test or ...?

Appreciate the help guys. I'm def not a mechanic.


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Might I suggest that after you have driven it and it is good and warm, lift the hood and see if you can smell coolant. Radiators can develop very small leaks that evaporate before forming a drip. Had one like that on the wife's car. Put some stop leak in it and fixed it that way

I'll try that. Smell was what led me to my radiator earlier this year.

How long does it take to disappear? I try to remember to check my overflow bottle every few months, it's not empty but it's not at the low line either.

30-45 days & I'm low or empty. But isn't this a closed system? None should be getting out right?

The 01 is and open system. The older XJs had the closed systems. I can't remember which ones exactly but it believe it was the Renix engines that had the closed system, someone will correct me if I'm wrong? Either way, again if memory serves me correctly, anything 96 and up will be an open system.

So, in an open system, where would the coolant purge out? Thru the coolant overflow?

I filled my overflow tank last Thursday, last night it was just below the add line. Now I have been driving it hard, high rpm on highway, county roads, but that just seems like a lot of coolant to lose in under a week. No puddles in driveway, no coolant smell, oil doesn't look milky. I'm at a loss & it's driving me nuts trying to figure out where it's going

Yes you are correct. If it's going out anywhere it would go out the coolant overflow tank. The other somewhat unlikely possibility is that it's getting hot enough to actually evaporate in the system but it would have to be very hot for that.

Engine temp gauge appears to read normal temps, I wanna say around 210 or so. I don't notice any smoke or anything that looks like evaporated coolant coming out either.

I do notice the oil pressure fluctuations with the microguard oil filter. Low pressure at startup, increases as rpm's increase.

My guess is that it's either puking out as you're driving or there's a small leak at operating temp like was stated before.

That's making more & more sense. Seems like longer drive drives, i.e. Longer duration at operating temp, more coolant lost. How do you track that leak down?

Look for smoke or white crusty gunk on stuff in the engine compartment is a start. Radiator, hose connections, water pump, heater hoses.

Thanks! I'll pop the hood & take a look later today.

I had the same problem for about a year. Never could figure out what it was until I drove it for a long time on a hot day and then searched around with it running. Turned out my lower radiator hose clamp was just a teeny tiny bit loose and it was very slowly seeping out. :bang:

Definitely check the hose ends like Abe said. They can crack and get corroded and coolant can seep out. Had its happen a couple times myself.

Also sometimes when the water pump is going out it will leak from its "weep hole". While it's running get up under the front end and check the bottom of the water pump, being careful of moving parts of course.

And it's not probable since it's running fine but you can do a compression test to check for a head crack/leaking gasket. You can rent the tester from the usual auto parts stores and it's easy to check.

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