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WJ Fan 06-18-2012 01:22 PM

Intermittant coolant leak- Air conditioning system?
OK, got one overland fixed (4.7HO swap) only to have an issue spring up - unpredictable coolant loss.

This 2002 overland has 107K miles.

Here is the story- Son who has had the truck calls me up saying that there is a warning light for low fluid level, and what should he do. ADD COOLANT BEFORE DRIVING (I try to keep from yelling the obvious over the phone). After I get over my overheating, I call him back and say that no matter what else he does, please find a way to add more water before he drives it. No, at this point to not worry about antifreeze, no it does not need distilled water. Just get water into the radiator after it cools off. And then get the truck back up here and swap for the other overland that I just finished fixing.

So, he drives the truck back up from Hotlanta (early AM) and the fluid levels are fine. No leak in the driveway. Then the wife takes it out and she gets a low coolant light, checks into friendly local gas station (how did she find one that would actually help her?) and they add about a gallon, and she scoots back home and parks.

I go out about 2h later to see what I can see, fire it up, no leak.

Then I remember reading somewhere about an air conditioner-related issue with intermittent coolant loss. Yet another WJ quirk. So I fire up the air, set it on max cold and watch. 15 minutes later, a steady drip from right rear of the engine compartment, but the block seems dry. Definitely coolant.

Fortunately, the other 2002 WJ Overland already had that problem corrected.

Here are the questions-

How do I best tie down the "diagnosis" of the intermittent loss of coolant which may be due to a leak in the air conditioner apparatus?

Words of wisdom concerning getting the repairs completed?

Thanks in advance, and looking forward to any comments or advice.

WJ Fan 06-18-2012 01:59 PM

Re: Intermittant coolant leak- Air conditioning system?
Sorry- heater, not air conditioner.

Frango100 06-18-2012 02:29 PM

Re: Intermittant coolant leak- Air conditioning system?
Normally a heater core leak appears inside the cabin, at the passengers footwell.
It is maybe possible that the coolant comes out of the drain from the HVAC housing in the engine bay, where normally the condensation water comes out.
When you say that you put it on max cold, do you mean that the AC was on as well? If that was the case, then it is normal that condensation water comes out of the HVAC drain in the engine bay.
No white smoke coming out of the exhaust?

hoffmanestates 06-20-2012 06:32 PM

yeah. I had a headgasket fail on me cylinder #8. pressurize the system and.check.for.leak with the heater control knob on hot(red) and cold (blue) and check for drips
but if heater core failed u would get a sweet smell. check the heater lines on passenger side above valve cover
Turbo charged G2X using tapatalk 2

2005JGC 06-21-2012 12:26 AM

Re: Intermittant coolant leak- Air conditioning system?
could be head gasket, but you would be supprised check your radiator cap ;) I have seen one not leak sitting there idling, but you rev it up to 2k-2.5k rpms and all the sudden coolant pours out from around the cap... not that my revving test is legit, actually pressure test it (or replace it whatever you want).

Me Fix 06-21-2012 08:07 AM

Re: Intermittant coolant leak- Air conditioning system?
When you leak coolant into a cylinder through a head gasket crack, doesn't that cylinder cause a misfire or shake in the idle. Also it may cause a long crank to start issue or at least longer than normal crank. Then you might see steam or white smoke from the exhaust pie like Frank pointed out. if you are buring coolant, that can contaminate the O2 sensors which would set an error code, prohibit the ECM from going into a "closed loop" run condition and reduce fuel milage.

Have you looked at the overflow container. Does it look normal? Like Arron suggested, a raditor cap can cause problems too. The cap also has a check valve to help control the back flow of coolant when the engine cools and draws the overflow back into the engine as it cools. Is the upper radiator hose colapsed after the engine cools? You could always pull the plugs are check color. Also is oyur oil level up and or milky. Water in a cylinder will not compress and so if a cylinder is full of water, you might not even be able to crank over the engine if you had a major leak of coolant into a cylinder!

hoffmanestates 06-21-2012 10:56 AM

so our theory of head gasket u are saying is not feasible

Turbo charged G2X using tapatalk 2

Me Fix 06-21-2012 01:04 PM

Re: Intermittant coolant leak- Air conditioning system?
OH NO! The head gasket could very well be at issue. I've delt with more than one head gasket issue. One allowed coolant into the oil passage which then mixed with the oil. I had a head gasket on our boat engine allow water into the cylinders. I had so much water in there, the engine would not crank. I was very lucky that I didn't keep trying which may have bent a piston rod because like I said, water will not compress.

I'm sorry for the confussion! I just wanted to suggest some of the things I knew about and have delt with in the past. Your problem may be something even different than anything suggested by any of the others as well. Once you figure it out, please post your fix so we can all benefit from your bad luck.

WJ Fan 06-22-2012 07:22 AM

Re: Intermittant coolant leak- Air conditioning system?
Sounds to me like a trip to the dealer may be in store...
Truck runs like a top, so I doubt the blown gasket theory, but that is always a possibility. Am inclined towards the heater core, but we shall see. will check the overflow tank- good tip, thanks. I guess what I was trying to ask is whether there were any insights RE: the heater core, which as I understand it is a common fail about now, and not an easy fix in WJ. Is the latter true?

Frango100 06-22-2012 07:47 AM

Re: Intermittant coolant leak- Air conditioning system?
The heater core is indeed quite a job to replace. The HVAC housing must be opened, what means that the complete dash has to be removed. When you are in there, look also at the state of the AC evaporator and change it at the same time, to prevent pulling the dash again lateron. Maybe also a good idea to change the blend doors, because they are also well known for breaking on the WJ and can only (properly) be changed with the HVAC housing out.

Me Fix 06-23-2012 07:42 AM

Re: Intermittant coolant leak- Air conditioning system?
Excellant advise! If yuo pay to have someone, a dealer or whoever to take apart the dash to get to a problem within the housing, why not do as Frank suggests. The cost is in taking out and putting back the dash hoping they did it all right.

2005JGC 06-23-2012 04:31 PM

Re: Intermittant coolant leak- Air conditioning system?
You can look for youself on the heater core, grab the carpet under the dash on the passanger side where near the trans tunnel and pull it back (typically you can see it without doing this but this will be very clear) you will see a schputz trail down from the hvac box down to the passanger floor board.

Just to say this, the last head gasket job I did on a 4.7l wj it drove like a top the only reason it was in was becasue it was overheating because there was no coolant, put my leak down tester on cylinder 1 and I got a bunch of bubbles coming up through the radiator. How it runs is not peticularly an indication of a failure (or lack there of).

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