Where is the PCV valve located on a 1999 Mercury Mystique?
OK - just replaced mine. Stand facing the front of the car. Go to the right side and find the air filter assembly. You may want to get a light to see better. The PCV is about "2 o'clock" from the air filter under a bunch of stuff. It's tight, but look for the general shape of the new PCV valve you are using the replace. Bottom part fits into an approx. 5/8" hose and then there's another smaller hose on the side (keep the one from the old valve as you will need it with the new one). Just pull on the old valve to get it out from both connections and replace with the new one. Took 10 minutes TOPS and is very easy.
The PCV on a FOUR CYLINDER is located on the block in the CENTER of the front. It is hard to find and it is on a metal tube that is BEHIND the thermostat. The thermostat housing MUST BE REMOVED AND THE BOLT THAT HOLDS THE TUBE TO THE HEAD MUST BE REMOVED, after that, pull on the tube and the PCV is on the end which inserts into its place on the block. I found this myself after asking three so-called mechanics.