If you are talking about the coolant cross-over, on the intake, then the new modified one has to be installed. cost around $ 250.00 for the part, and 6 to 8 hours labor.
No, not as standard.
Intake manifold gaskets are leaking, intake manifold is warped.
The intake plenum is simply the top of the upper intake manifold, where the throttle body is attached. It is made of black plastic.
alot
No, not for the hose but, I have seen the metal bypass tube that the hose connects to, rust out and cause a coolant leak out the back of the engine. The intake manifold would have to be removed to replace that metal tube.
There is really no safe way to repair this. You have to change the intake. This is about a 6 to 8 hour job. The oem intake has a defect. At this point Ford will not do anything for you. The old intake has a plastic cross over, which after time will crack. The new intake has been modified. Check around the net, you can find one for around 200. $
The intake manifold is underneath the plastic silver cover held down by four nuts. Take it off and you'll find the intake manifold - also plastic. Even more unusual, the starter is underneath the intake manifold!
For the manifold see link below for detailed info on the class action settlement and detailed DIY instructions... http://www.autoclinix.com/Manifold.htm Is the intake cracked? Is it a 4.6L? If so, a recent class action settlement extends the warranty, on the intake, to 70,000 miles. Don't replace with OEM manifold.
YES , a 1990 Mercury Grand Marquis 5.0 liter V8 engine has a PCV valve ( Motorcraft part number EV-98-B ) going into the intake manifold
mass air flow sensors are generally located in the air passage between the air filter and the intake manifold.
The Villager has an upper and lower intake manifold. It is at the top of the engine with the throttle body attached to it.
There are 2; one on each side of the intake manifold toward the front. See pics and description here... http://www.autoclinix.com/Manifold3.htm