Gas cap oddity

[AtLarge]

I searched the forum and didn't see anything like this so maybe someone here has experienced this already.

My gas cap was hard to latch in the closed position. Key moves freely in the locking mechanism.  I bought the OE rebuild kit and swapped everything around thanks to the Harris video.  Thoroughly cleaned and everything went back together fine.  I even used a smattering of anti seize on the touch points of the pop out latch.  It's still kind of a struggle to push hard enough down on top to get it lock closed.  (pop out and clear the edge of the mount)  Don't know why and can't figure out where the interference is coming from.  The three screws through the foam gasket are about as tight as I dare to go so, can't really compress it any further.  The odd part is too, is my cap has an additional spring and valve in the "domed" part of the cap that you have to pop off with pliers.  The one in the video and the OE parts fiche doesn't show that part of the assembly at all.

So, I'm wondering what that is (pressure relief valve)?

Also, do you think it would help if I added three thin stainless washers to the filler neck shield to move it down slightly and then allow the dome to drop a little further and hopefully latch easier?

 

[frankenduck]

Just give it a good smack with your hand to close it.

[Laitch]

The odd part is too, is my cap has an additional spring and valve in the "domed" part of the cap that you have to pop off with pliers.  The one in the video and thess washers to the filler neck shield to move it down slightly and then allow the dome to drop a little further and hopefully latch easier?

Remove any parts you have that are not in Harris's video. Wonder about them later. If you removed the latching cam at the base of the assembly, verify that it is oriented correctly according to Harris's final assembly. Remember that he failed to preload the latching cam the first time through so check that. Verify that there are no duplicate gaskets in the assembly. Assemble and close.

[AtLarge]

Ya, I did wimp out on the preload when I did it the first time.  It still returned the key rotation but, certainly not as strong as it could be.  Dived back in and figured out the problem.  The large round gasket from BMW is about 3.3mm thick.  I put the old one back on which was still pliable and mic'd at 2.5mm and in combination with the stronger latch return was the ticket.  Closes with that satisfying click now and the key definitely springs back around.  That preload probably was the real cause to begin with.

I went ahead and put that valve and spring back in too.  I figure they must have had it there for a reason and it wasn't the cause of the problem anyway.  I put a NAPA Gold 3032 fuel filter in as well since I was already in there.  We're good now. 

Thanks for the help!