My 97 4.0 is leaking green coolant right by the driver side bumper. At first glance, it seems very obvious that it is the hose by the air box. However, I replaced the hose and the clamp and it didn't fix anything. I also re-sealed the plastic cap that is near the radiator cap. Since I replaced my rad cap recently as well, I then decided to do a pressure test. I removed the air box to see where it was leaking, and got it up to 17 psi. After 10 minutes the pressure didn't really fall, however a lot of coolant started leaking from the regular spot. The hose and plastic cap stayed fully dry though.

Here is a video (https://photos.app.goo.gl/SHtw7MLesy2Ek9fH9)

It leaks intermittently, sometimes dumping coolant after coming home from the gym, sometimes barely leaking after long rides. Two winters ago I forgot I had water in the system and it froze over one night, I'm thinking maybe that could have started a slow leak in the rad that just didn't become know until now. The system seems to be holding pressure, despite leaking though? I think I need to replace the radiator, but just want to get some feedback before I blow money on that. Anything else I should check?

 

I'd say eliminate the possibility of the hose clamp by putting a fine, sticky powder around the question area. you could have a fin leaking by. a blush powder from makeup should be sticky enough, or even something like crayola markers that will run with water. chalk, talkum, etc

 

How old is this radiator? If it's older, you won't be blowing money by replacing it; money spent on your cooling system is the best money you can spend on your XJ.

Radiators all fail eventually...often at the seams on the sides of the radiator. The leaks most always start small and subtle, but if the radiator blow out when you're on the road which is not at all uncommon, you'll have bigger fish to fry. Radiators are not expensive, quite reasonable in fact. If you can't find a definitive leak that is not the radiator, just replace the radiator.

If you can't remember when the thermostat has been replaced, do that at the same time. 195 degree. I like MOPAR stats purchased directly from Jeep.

 

radiator is maybe 5 years old, however like I said it froze a few years back. I'll get the thermostat too! Thanks for the advice.

 

Ok, I will do this. I was skeptical too because it seems like such an obvious spot.

 

Also, do you know if the radiator comes with the transmission cooler? or is that separate?

 

It looks like a plastic-tanked radiator, right? Possibilities could be:

1) Rubber seal where plastic tank meets radiator body (and corrosion built up underneath it). Replace radiator. Actually the tanks can be removed and the rubber seal cleaned, but that's more work than the average guy wants to do.
2) Molding flashing on the plastic hose bib. It's real common there's flashing or a hose bib is not molded right. It used to seal but now doesn't. Fix is to remove the radiator and file down any molding flashing that might allow coolant to leak.
3) Cracked hose bib. Sometimes they can crack. When it happens check the motor mounts. If the engine 'rocks' they often break/damage hose bibs. Put vehicle in gear, hold foot on brake, watch engine between the crack of the open hood and the engine. Do the same in Reverse. If you see the engine rock a lot, it could be motor mounts.
4) Leaky hose
5) Leaky water pump seal (is the hose dry underneath?)

Good luck

 

Thanks. I will check the water pump seal, but the hose was pretty dry throughout so I am leaning towards rad problems. If I have to take the rad out I'm just gonna replace it. I really appreciate the advice.