White plastic retaining ring on the filler neck

[oldschool1]

<OS scribbles notes on hand>
"filler neck grit-blasted and then paint"
"rust preventing/sealing paint"
"filler necks are no longer available"
"The Eagles will win the Super-Bowl"
<OS scratches out one item>

[396427454]

Having now screwed this up myself once, then watching my neighborhood independent shop screw it up two more times, I had to look closer at the seal design, take some measurements, and draw it up to determine how it was designed to work.
Thanks to this forum for defining the part numbers required:
· Retaining Clip XS2Z-9149-AA
· Seal XS7Z-9072-AA
· Also to the descriptions for the tank R and R – such as post 25

A number of people have suggested that the seal should be placed on the filler tube, then the tube and seal inserted into the tank – this is how attempted it the first time (as well as how my local shop did it) – it leaked, and here is why.
The seal MUST be “snapped” into the tank fitting in order to seal – I believe this can only be done PRIOR inserting the filler neck - see figures below:
Presentation1..jpg
Note that the top of the seal is approximately ½” below the windows in the tank fitting. There is a very clearly felt “snap” when pushing the seal in. If the top of the seal is even with the windows in the tank fitting, it is incorrect, and will leak.
Lightly grease (I used Vaseline) the filler neck. Place the white snap ring on the filler neck. Carefully center the filler neck in the seal as you push the tank onto the filler neck – when greased it doesn’t take much force to slide the tank with seal up the filler neck, but there is some maneuvering of the tank around the floor pan and other obstructions. Concentrate on getting the filler neck fully seated into the tank and seal before trying to push the tank up into the floor pan cavity.
Here is what the finished joint should look like in cutaway:
Presentation2..jpg

[Redlineracer12]

Nice post and drawings! Those explain why mine leaked at first then mysteriously quit not long after. The seal must have worked it's way down all the way. So the important thing to note is that your seal is recessed inside the window of the tank (1/2") before you try putting the filler neck back in.

[396427454]

Thanks, and thanks to you for finding the part no.s, for some reason the no.s are not known at the dealers.

And yes, the key is 1/2" below the window. There is a very clear snap as it is pushed into position.

[CSVT#49]

This thread should be sticky'd or linked in a common questions thread.