Leaking Antifreeze

[Big Green]

Saw a little anitfreeze under the wife's TJ when I got home. It appears to be leaking from the upper corners only and the only place it has leaked enough to drip was passenger side. Her Jeep was outside last night (not uncommon) and it wasn't that cold, I did bring it in right before I went to work though. There is still plenty of fluid in the radiator, it was flushed about 18 months ago and it is still protected to -25* according to my tester. It is 99 TJ with the 4.0, appears to be original radiator and 176k. Any ideas?

Pictures zoomed in to show detail.

Passenger side, back side of radiator.


Passenger side, front side of radiator.


Driver side, front side of radiator.


Driver side, rear side of radiator. Very little fluid here.

[HillBillE]

My guess would be the upper tank is cracked, in the corner/end of the first pic.

Doing a pressure test on it will verify that, or at least help to find the leak.

Some parts stores will do the test for free, or the Hobby Shop may have a tester (if you have access to one)

Or, to do it yourself, top off the fluid (when the motor's cool, of course) then bring it up to operating temp. This should bring the pressure up to 10-12 lbs. (don't recall the cap rating off hand)

Once it's warmed up, shut it off and look for leaks. The pressure will build slightly, once the fan is off and not cooling anymore.

Using a tester is nice, becuase you're not dealing with 200* antifreeze

[HillBillE]

Blowing up the pic, I noticed an anomoly. Right hand circle, looks like a possible crack?

Left hand circle- the hose may have a pinhole leak, only leaking under full pressure. Hose looks bulged right there.

Arrows-top tank might be cracked under the mount.

Never have liked plastic radiators

[Big Green]

My guess would be the upper tank is cracked, in the corner/end of the first pic.

Fixable? At least temporarily?

[HillBillE]

Fixable? At least temporarily?

No idea. I've never tried to repair a plastic one.

Make sure it's not the hose first.

Things I have used for small leaks (on brass rads)

Pepper (it works!)

Crack a raw egg into warm radiator and replace cap. (Just like the black pepper, it goes to the leak and 'sticks')

Alumi-seal

[Big Green]

The "crack" does not appear to be a crack.

The hose looks good. The "bulge" is the portion of the radiator that the hose slips on to and the angle makes it look bulged. Also, the way the fluid is spread out around the radiator would make me think it is not the hose.

I also don't see anything behind the mounts that looks cracked.



So if she drove this thing it would start spraying antifreeze everywhere huh?

[HillBillE]

So if she drove this thing it would start spraying antifreeze everywhere huh?

Probably a bit. It doesn't look like much so far, but it came from somewhere.

The pressure in the radiator will be between 8-15 lbs generally. (I don't recall what the 4.0's run at.)

I wouldn't take it on a long trip without fixing it

On my old truck, I ran it with the cap loose for a few weeks, until I could fix it. Cap loose=no pressure, so the hose didn't leak. Not sure how well that would work on a newer rig.

[Big Green]

What about alumaseal for a few days till I can get this taken care of?

[HillBillE]

What about alumaseal for a few days till I can get this taken care of?

It's only a couple bucks, I'd try it. (Alumi-Seal or Gold-Seal)

Not sure if it adheres/plugs plastic. But the leak may be in the brass, or where the tank and metal join.

There is also 'BarsLeak', but I've had problems with it clogging the heater cores on old rigs. (Old as in pre 70's) Shouldn't be a problem with the newer rigs.

[Big Green]

It's only a couple bucks, I'd try it. (Alumi-Seal or Gold-Seal)

Not sure if it adheres/plugs plastic. But the leak may be in the brass, or where the tank and metal join.

There is also 'BarsLeak', but I've had problems with it clogging the heater cores on old rigs. (Old as in pre 70's) Shouldn't be a problem with the newer rigs.

I've heard the same thing a lot about the BarsLeak and stop leak or something.

A couple of guys in my other club are recommending black pepper. I have heard enough that it works but need something a little bit better for now.