EHarris

Taking a look over the JK before a trip this weekend and the thermostat housing is leaking some coolant. The bolts are snug and the thermostat and housing only have about 20k on them. How do I stop this? I've never noticed it before. All Mopar parts. I don't remember this being normal.

resharp001

Yup, that doesn't look good at all. Time for new housing/thermostat. Fortunately not much money, and you shouldn't loose much coolant in the process. I know it doesn't seem like much life at all, but seen brand new ones on new jeeps fail in that time as well. Does it look like some is leaking down from the hose, does it just look like that in picture? I tend to like the factory tension clamps better than the worm gear hose clamps.

tjkamp

You should replace that worm gear clamp with the factory style constant pressure clamp. That worm gear will never ever hold a seal with that plastic housing.

To me it looks like it is leaking from the clamp not the housing.

Mark Doiron

The thermostat has an O-ring around the lip of it that makes the seal with the housing. If that O-ring is pinched slightly--and it's easy to do--you can get a leak. Open it up and take a look. Might have a new thermostat on hand just in case. Also, you can buy, though it's not required, a gasket from auto parts stores for the thermostat housing. The seal on the thermostat itself is supposed to prevent leaking.

resharp001

Took another look at those pictures this morning, and gonna stick with what myself and tjkamp mentioned....zoom in and you can see the dried streaks where it's come down from the hose, over the top of the housing. I think it's that clamp. Whole new thermostat doesn't cost much, but if you can get your hands on a factory tension clamp, pull the hose off and replace clamps, that might fix your issue. On the 2nd picture, you can even see the tiny trail over leaving crusty remains by the bolt.

tjkamp

I had this issue on the radiator side of the upper hose. I had the system flushed at one of those quick lube places, and they replaced the factory clamp with a traditional hose clamp. I didn't want to hear about how it would leak, so I fought the leak for a year and a half constantly tightening the clamp, the leak would go away for about a week and then come back. Eventually I got the clamp tight enough that I ruined my radiator hose. When I replaced the hose, I went to the dealer, and got one of their factory clamps ($8 and change) haven't had any problems with the leak since.

EHarris

Thanks boys. I have the old ones from the old hoses I can put them on for sure but I'll see if I can't find some brand new ones.

I can see how you could think it's leaking from the hose but I think it's more of the housing. But easy solve is to throw the other clams on.

Just disconnect the upper hose, a small amount of coolant will leak out but whatever and put the new clamp on. Anything I'm missing here? I'm at 140k on my OEM radiator. Was gonna replace it anyway this summer before it left me stranded on a trip. If the clamps don't fix it I'll just do everything now.

resharp001

Correct. You shouldn't lose much coolant at all. Once reconnected, you can disconnect the upper hose at the radiator and pour a little coolant back down that hose, then obviously burp the system best you can....but there shouldn't be much air in there for the little you're doing. I know on the 3.6L the thermostat housings have a bleed valve which helps. I don't see one in your picture on the 3.8L.

Should go without saying, but use Mopar HOAT if that is what is still in the system, don't mix.

EHarris

Got it. I will attempt this weekend. Thanks. I'll update.