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.
>
>
All vehicles use a coolant recovery system because the coolant is toxic
to the environment. The radiator cap has two valves. The large rubber
one allows coolant to escape under pressure into the coolant bottle.
When it cools down again, vacuum in the radiator is supposed to suck the
coolant from the bottle, through the other valve (the small metal one in
the center of the rubber one) and into the radiator. In order for this
system to work, the seal between the radiator flange and the top of the
cap must be tight. Some caps use a metal plate as a seal, but the better
ones use an O-ring or rubber top plate. If your cap looks okay, check
the hose leading from the radiator to the bottle. Most use clear plastic
tubing that just slips on and it can get brittle over time and leak.

--

Bill Lahr