Hi everyone,

My 2000 JGC 4.o Laredo has an intermittent coolant leak. When the vehicle sits overnight or a day or two, I have noticed a trickle of coolant coming from the top hose on the radiator end by the clamp. I clean it off, drive it, check it and when it is warm it does not leak a bit. This has been happening on and off since early October. I want to chalk it up to expansion and contraction since it has been so cold here in southeast NYS for the last few weeks, but I want to be safe.

Visual inspection reveals:

1) Some minute spray of coolant (5-6 very small spots) on the fan shroud (probably from cold start up) This is what really bothers me.
2) A trickle of coolant down the side of the radiator.
3) A small mirror and flashlight aimed under the connection shows a green residue on the front end of the clamp. ( It is a worm clamp with a screw)
4) No odor of antifreeze emanates from the engine bay at all.
5) No temp spikes, vehicle warms up nice, runs at temp where it should.
6) Coolant level in reservoir is perfect all the time.

Again, if I wipe it, and drive away it does not leak at all.

In addition:
1) The radiator, water pump & all hoses were replaced less than 10K ago and system was flushed.
2) Had the top hose off when I replaced the thermostat 9/14 @ 157,506 (now 160,700).

I'm thinking its the hose and the clamp that should be replaced. Visually all seems in very good condition (no cracks visible) but the spray concerns me a bit, as it is clear that it some coolant is escaping under pressure.I am hoping for no crack on the (plastic) neck of the radiator, since that is an expensive piece. I am having some other work done on it tomorrow (coil spring insulators), and I have asked my trusted mechanic to check it out.

Any advice?? Thank you so much for reading.

 

One thing you can do to eliminate the hose as the problem is use a double clamp at that location, putting the screw sections in opposite sides. Some times the screw section doesn't create a perfect seal and allows leaks under it. I had this problem on my Chevy truck and the double-clamp did the trick. If it doesn't, it's possible the rad neck is cracked, although that usually makes for a bigger leak.

One other thing. When the old hose was removed, did a razor knife get used? If there is a groove cut in the plastic, that can cause a leak.

I'm chasing a small coolant loss in my WJ, but that's the reservoir has to be topped off every 2 months or so. People are telling me it's a crack in the head, but I doubt it because the exhaust doesn't smell and the loss isn't big enough. No smell from under the hood either.

 

Thanks for the input. Your comment on your own coolant loss leads reminded me that since this started I have not had to add but about a few ounces to the reservoir and the level hasn't really changed that much at all. I am hoping beyond hope that it is not a cracked neck, and I agree with you that that would be a much bigger leak. My fear is that if that is what it is, that this is all under pressure and that one day it is just going to give out and burst at an inopportune time. I am going to ask my tech to check the hose and if that hose is compromised to replace that hose and use a different clamp system and see what happens. I really appreciate your input, will keep you posted.

 

Look for cracks in the radiator tank below the upper hose neck.

 

No cracks found in the radiator neck, replaced clamp and retightened. Will see where this takes me. Drove it home from the shop, looking good, will check in the AM as its supposed to get to about 2 degrees here tonight.

 

Pull the hose off and coat the inside of hose with indian shellac. I guarantee you it will not leak.

 

Yes, that works, but it makes it a PITA to remove next time.

Busted's right. If you torqued on the hose while taking it off, you may have cracked the seal where the tank goes into the radiator body. I've cracked the solder on brass necks before when I wasn't careful. Young and stupid, you know.

 

I have this exact same issue on my WJ. Have to add coolant about every 3 months. I've had my oil checked and there is no coolant present. Plus I feel like the head problems are normally found in the 4.7's and not so often in the 4.0's. It has never gotten worse and it has done this for 4 years now. Again I would think if there was an issue with the head, it eventually woulda gotten worse.

 

The only conclusion I've come to is it must be evaporation from a loose fitting reservoir cap. I've seen a small amount of liquid dripping out of the tailpipe when you sit and idle for a while, but that's clear water. It doesn't smell and tastes like water. Yes, I've tasted it! Gotta know for sure, right?

 

Interesting conversation here.

First, what is this "indian shellac" that you speak of?

Second, This vehicle has been in the family for the last 5 yrs, until I bought it from my brother last August. Because it has been so cold here in NY the last two weeks, I have let been letting it idle for at least 4-5 minutes before driving it, as I keep it outside. I get A LOT of water coming from my exhaust (at the tailpipe & muffler drain) and my brother has told me it has always done that to no ill effects besides me having to replace the tailpipe in September due to corrosion. I am not worried about that.

This to me seems unrelated to this problem. I did check the cap on the radiator and that is tight. Reservoir cap is tight as well. Yesterday (Sunday), morning low temp was 10. No leak. Drove it, saw a TINY dry* spritz ( I know...fruity word) of coolant on the shroud again but no drip. My tech and a trusted friend who is a service mgr told me to monitor it regularly (and I have been) and drive it, because I am basically losing so little that I haven't had to top the reservoir and shouldn't be overly concerned at this point.

On that note, I WAS told to watch it closer when the weather warms up since I know common sense dictates higher outside temps (spring & summer) put more stress on compromised cooling systems.

Any more thoughts guys? I really appreciate all perspectives.

 

I don't know what "indian shellac" is , but shellac is an alcohol based sealer for wood. My grandfather used the same term, so maybe there was an Indian brand back then. I've used shellac for wood spars on sailboats and it penetrates deep so maybe it soaks into the rubber hose well. All I know about using it on a hose is you have to just about cut it off with a knife to remove it.

One thing I'm going to suggest. When it's cold, after starting my jeep, I shift to neutral to allow the transmission to start circulating fluid and pressurize the system. It helps soften up the old o-rings in the transmission and makes it shift better when you start moving. I have a couple of small dips in my driveway where I park so I don't need the e-brake.

 

A gasket sealer sold by permatex. Not really shellac. It is fairly thin in consistency, comes in a small bottle with a brush applicator inside. Very effective for hoses and water pump gaskets....used for years by "old school" mechanics....also used in aviation.

 

Yeah, okay, so I had a brain fart! Now I remember. You are right, but I haven't seen it in years. I'm an "old school" mechanic that's trying to learn new ways.

 

I've experienced the similar type of leak your describing. A good solid push on the wet spot revealed a larger crack in the plastic rad.from what I can assume is the cooling system had enough pressure to "seal" the crack when it was running. I would find this "spritzing "you speak of after the WJ cooled a bit. Just be careful doing this while hot,you could end up with an eyeful of hot coolant ,ask me how I know.