Your cap has 2 seals. One at the rad and one at the top lip of the
filler neck. This is so the fluid that comes out of the rad as it heats
up is contained at the top lip and sent to the overflow bottle. Then
when it cools down, the top lip seal holds so it sucks fluid back to the
rad.

I would suspect either a deformed top lip on the rad or a leak at the
overflow tube or a leak a the neck to rad joint.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
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YouGoFirst wrote:
>
> I have a 1993 JGC with the V8 engine. Recently it has begun to leak a fluid
> out of the radiator cap. It only leaks fluid after the engine has warmed
> up, and is cooling down. I was able to follow the trickle of coolant to the
> radiator cap. At first I thought that the cap was bad, so I replaced it
> with a new one from Checker Autoparts. That didn't seem to work, so my next
> thought was that it is building up too much pressure. The only problem is
> that I can't think of a reason why it would build up extra pressure. Is
> this a possible sign that my water pump or radiator is dying? Or, does
> anybody have another idea.
>
> The only thing that has changed on my car was that I had the oil and
> transmission fluid changed before I noticed this problem. Also, I had a new
> radiator put in 2 years ago, and a new fan put in last year.