"crossover tube"... (??)
If this is referring to the coolant bypass hose/tube, we've got you covered with the "Related Question" below.
If not, please elaborate on what/where/symptoms are related...
The crossover tube has an O ring at the end, it is plugged into the intake manifold and held in place by 2 screws. See pictures here: http://leckemby.net/windstar/windstar01.html
You could, but you will have to buy a new line to get a new orifice tube.
BEFORE YOU DO THIS: Be aware that if you are doing it because of a a knock sensor code, it is most like uneccesary. A knock sensor is a passive device that has no effect on normal engine operation. Mercury Villagers are notorious for throwing knock sensor codes when nothing is in fact wrong with the knock sensor (which produces no current under normal conditions). Because of the way emission components are wired, problems in front oxygen sensor wiring harness (common) or the throttle position sensor can also cause this code to be set. Many of these sensors are replaced uneccesarily. Know also that this is a fairly involved job which will take the better part of an afternoon if you are fairly skilled. You will need to drain and refill the cooling system, and you will be disassembling a number of pipe connections that have to be reinstalled with either aftermarket gaskets or assembled with RTV, which can be tricky to get right without leaks. Here is the procedure for replacing the knock sensor on a '01 Mercury Villager: --Removal-- 1. Remove the lower intake manifold. 2. Disconnect the heater core hose from the coolant crossover tube. (refer to the diagram in the 'related links and sources' portion of this answer) Release the clamp and disconnect the hose. 3. Release the clamp and remove the lower radiator hose from the coolant crossover tube. 4. Remove the water bypass hose from the thermostat housing. Release the clamp and remove the hose. 5. Remove the coolant crossover tube. Remove the bolts and tube. 6. Remove the Knock Sensor (KS). Disconnect the electrical connector. Remove the bolt. --Installation-- 1. Install the knock sensor and bolt. Connect the electrical connector. 2. Install the coolant crossover tube. Position the coolant crossover tube. Install the bolts. 3. Install the water bypass hose. Position the hose. Position the clamp. 4. Connect the lower radiator hose to the coolant crossover tube and position the clamp. 5. Connect the heater core hose to the coolant crossover tube. Connect the tube. Position the clamp. 6. Install the lower intake manifold.
Remove the air inlet duct tube. Remove the heat shield from the exhaust and move it out of the way. Unbolt the crossover exhaust pipe bolts from the from the front exhaust pipes move it out of the way. Unbolt the thermostat housing pipe and remove the thermostat. Installation is reverse.
The orfice tube is located in the evaporator inlet tube. There is also an expansion valve in the rear evaporator case.
It's located on a vertical aluminum tube on the firewall. Between the junction of two lines.
Follow the high-side line from the charge port to the firewall. The line breaks with a screw fitting. The orifice tube is inside the line where that fitting comes apart. It's virtually impossible to get to with the engine in the car.
At the front of the engine under the housing that attaches to the coolant crossover tube assembly.
Tube Slider happened in 2003.
Tube Slider - 2003 VG was released on: USA: 18 April 2003 (Gamecube version)
James Brown - I Want You So Bad
Tube Slider - 2003 VG is rated/received certificates of: USA:E