Well, it looks like the new radiator I installed in April is leaking already. It is a 2 row all metal model from a reputable manufacturer.

I just noticed it today when moving the Jeep from one side of the street to the other. The Jeep was running for like 5 minutes, then I shut it off, and when I get out I see the wet spot on the ground on the passenger side. I checked the hoses, water pump, and they all look dry (shone flash light on them all). But underneath the radiator (on the frame shelf it sits under) and by the AC condenser it does look wet. The location makes it look like it's from the outer most side of the radiator on the passenger side.

So I started the Jeep again and let it run for another 10 minutes and nothing. I can't get it leak now that I am looking at it.

Anyway, before filing my warranty claim I am going to pressure test the radiator. The RA website also tells me to check for Electrolysis. Does it happen with XJs?

Thanks.

 

Yes. Electrolysis will happen when any different metals are in contact with a shared liquid. Aluminum, iron, steel and brass will form a "battery" of sorts. That's why keeping the proper antifreeze and DISTILLED water in a system is very important.

 

Upon closer examination, the new radiator is not defective.

Instead it looks like the leak is coming from the top hose connection at the radiator. Since the neck is metal, when it's cold, it is probably contracted enough to leak. But it does not leak until the thermostat opens up. And once it opens up, the neck warms enough to expand and seal the leak. Which explains why the leak went away once the Jeep warmed up. So I tightened the clamp some more. Hopefully that does it.

I also tested the voltage in the coolant and I got 250 millivolts, which I think is .25 volts, so that should be good from what I have read online about electrolysis.

BTW, a powerful LED flashlight goes a long way to finding leaks.

 

Correct 250 mV is a quarter of a volt. the milli part of it means 1/1000th. so 1 millivolt is 1/1000th volt, thus 250 mV is 250/1000 or 0.25 Volt. Weird is it not. one thousandth is called a milli. when I was a kid I though it meant one millionth, but I was wrong as a kid, but the word milli sure sounds like it should mean millionth, but it only means thousandth. The word micro refers to millionth a microvolt (abreviated as uV) is 1/1,000,000 Volt.

 

I like my trusty voltmeter, but every so often, it makes me work for the answers.