What is the Jack valve and where could it be located in a 92 mercury cougar?

Question

I heard an strange noise in my car´s engine when stopped, someone told me that it could be the Jack valve. What is it for?, where could be located?

Answer 1

IMHO- someone is pulling your leg.
The sound you hear could be one of a myriad of things.
It could also be something normal, like oil dripping down into the crankcase, or refrigerant still equalizing in the system, or coolant under pressure escaping the cap, or the engine could be warmer than normal, and what you hear is coolant (mostly water with less coolant) boiling under pressure.
If it is a noise you have never heard before, it is best to get an opinion from a mechanic or tech that can listen to and hear the noise first hand.
Trying to describe a noise of this sort is much like trying to describe the taste of a banana. it is pretty simple to understand, but very difficult to communicate something so subjective as a "noise".
Good Luck

Answer 2

It's in the trunk by the spare tire and lug wrench it reverses it's position when raising and lowering the vehicle.
I would ignore that someones diagnosis. Get a second opinion.