Here’s my reasoning of why it’s important to install the new oil filter element onto the aluminum post inside the oil filter housing prior to screwing on the plastic oil filter cap.
But, first a bit of info regarding the oil filter system based on my experiences with changing the oil and oil filter on the 3.0, and from looking at a replacement 3.0 oil filter assembly.
The oil filter element has a friction fit onto the aluminum post inside the oil filter housing, and the oil filter has a friction fit onto the base of the plastic sleeve inside the plastic oil filter cap. The friction fit of the oil filter element to the aluminum post is weaker than the friction fit to the plastic sleeve in the oil filter cap – that’s evidenced by the oil filter element always stuck inside the plastic cap upon removing that plastic cap for an oil filter change. And, the plastic sleeve inside the plastic oil filter cap which the oil filter element slides onto can be rotated relatively easily inside the plastic cap.
Regarding the infamous anti-drainback rubber valve, or “nub”, inside the oil filter housing below the oil filter; it’s held in place only by the small rubber “button” that extends through the metal spring. When the oil filter is removed, the high point is that button that’s holding the rubber anti-drainback valve in place.
Apparently, when the oil filter is installed incorrectly by first inserting a new oil filter element into the plastic oil filter cap, and then screwing in the oil filter cap, the oil filter element can rotate enough to cause the anti-drainback valve, the nub, to be dislodged out of the metal spring.
Thus, Ford advises the proper procedure for oil filter installation is to place the new oil filter element firmly onto the aluminum post inside the oil filter housing. Then, screw on the plastic oil filter cap (with a new lubricated o-ring).
With this oil filter installation method, the oil filter likely doesn’t rotate on top of the anti-drainback valve because of the friction fit of the oil filter element onto the aluminum post, and because the center plastic sleeve in the oil filter cap can rotate as the cap is screwed down. Actually, the plastic oil filter cap rotates as it’s screwed down, and the center plastic sleeve inside the cap does not rotate as the oil filter element is pressed onto the base of the center plastic sleeve inside the plastic cap.
But, what about when the oil filter is being removed, could the rubber anti-drainback valve be dislodged then? Possibly.
The mechanics of removing the oil filter: When the plastic oil filter cap is being unscrewed, the oil filter element is pulled directly up off the aluminum base for approximately 3/8” before it’s possible for it to rotate. That’s because the friction fit of the plastic sleeve base inside the oil filter cap is stronger than the friction fit of the base of the aluminum post, and the plastic sleeve can remain stationary as the plastic cap is unscrewed. Also, the base of the oil filter element that contacts the rubber anti-drainback valve is well lubricated with oil. Pulling up the oil filter element by unscrewing the plastic oil filter cap also allows the rubber anti-drainback valve to open by the action of the metal spring, thus draining the oil in the filter and housing.
Thinking of these mechanics of removal and replacement of the oil filter element, one good thing we can do is visually check to see if the rubber anti-drainback valve is in its correct position prior to installing the new oil filter element. We also can be relatively confident installing the new oil filter element by pressing it onto the aluminum post first is not likely to dislodge the rubber anti-drainback valve.
On the flip side, if the anti-drainback valve is not in its correct position, with the parts now available from Ford, a fix should be relatively quick and inexpensive.
My two photos, below, show the anti-drainback valve in its correct location.
