OK, enough is enough. Coolant leak at the Radiator Cap, started at about 5K miles. No other symptoms, runs and idles smooth no overheating, needle has never been above the mid-point line on temp gauge, heater works great. I bought a new mopar factory cap to see if I could eliminate the problem without a dealership visit. First couple days no leaks, but then started again. The more I fiddle with it the worse it has gotten with both caps. Only leaks as fluid is transferring to the overflow tank under pressure, once fluid expansion is stabilized and overflow to the tank has stopped the leak stops, inter seal is working fine and the suction of fluid back into the radiator from the overflow tank once cooled is no problem.

I looked at the lip of the radiator opening and all seems fine, no cracks on the securing flanges around the outside and the top lip of the opening is smooth and looks like it is a good surface to seal to.

Both Caps look ok but I did notice that the bottom lip of the cap where the flange is that forces the cap on tighten as you twist it shut looks like it may be slightly bent downward causing the cap to possible not fully tighten on the side where the leak comes from. I am going to bend it back a little to see if this will tighten the cap on that side. Also the cap will depress slightly when you push down on the right side causing the left side to raise up and lose the seal.

I have never had a Rad Cap problem in 28 years of driving so this is pissing me since this is practically a new vehicle, and I have driven some real “beaters” in my day.

Any other suggestions before I take it into the dealer this weekend?

 

Is it inappropriate to try to answer my own question in a public forum? Think I may know what I have done, to cause my leak to get worse, while removing the radiator cap being right handed, when I pushed down on the cap more pressure was being applied to the right hand side thus lifting the left side of the cap and bending down the flange on the cap. Guess that is better than breaking the filler neck of the radiator. This would explain why both caps have the same flange bend. I mean it is a very slight but under high pressure could cause the seal to be lost, I guess. Every time I removed the cap it bent the flange a little more causing my leak to get worse, All this being said, I will confirm this theory this evening when I get home. Note to all: if you need to remove your radiator cap make sure you push straight down. Hard to believe the cap is that fragile.

 

I hope you find this out, i have 4.5K on mine, and have the same issue!

 

It might not be the cap at all. I had a similar problem with mine when I first bought it. Made a hell of a mess under the hood every time it happened. Dealer replaced the cap a few times. Double clamped the radiator hoses (WTF! ). THEN........I discovered a tiny hole in the overflow hose just after the end of the barb on the filler neck. You couldn't see the hole when the vehicle was cold, but with the engine warmed up and a slight sideways push on the hose, coolant shot all over everything. Dealer tried three times to solve the problem (idiots)..............took me about five minutes. I only mention this because I've heard of a similar problem from other JK owners. It looks as though the install process for this overflow hose could result in this damage from the factory. Whatever yours turns out to be.........good luck.

 

hmmm. i will check that out asap. thank you!

 

I was correct in my speculation on my second post to this thread. Took the original Rad Cap, since it was leaking the least of the 2, and bent both flanges slightly upward to create a tighter seal with the outer gasket. Installed the Cap and idled the engine until the electric fan kicked in. Water in the overflow bottle rose about ¾ inch. Let the engine cool back down to make sure it was siphoning the overflow liquid back into the Rad. So far so good, no leaks at the cap and the coolant is flowing as designed. Just to make sure I ran her hard for a few miles and rechecked for leaks. None. Will monitor for a few days. Still have my fingers crossed that this was actually the prob.

What a wimpy a$$ Rad Cap. If just removing it will make it fit loose enough to leak then I will never touch it again. Never had this prob on any other Rad cap I have ever removed and re-installed. Just a heads up to make sure you push straight down on it if you ever take it off. Also check it after anyone has messed with it after a Service. I seem to have bent two of them and I am not that strong of a Dude. Guess I could have bought a 3rd Cap or actually had the dealer replace it under warranty but that would not have been any fun.