Anatomy of a Gas Cap

brewsky · Post by **brewsky** » Tue Apr 20, 2010 7:11 pm

Was getting ready to trash my old rusty original gas cap when I read Rustywrench's comment about taking it apart with a hammer.
Sure nuff it works. I ended up putting it in a vise and using a punch to get it all the way separated.
Parts went flying everwhere!
The chrome dome you see from the top is press fitted on top of the other SIX parts.
It was so rusty, you couldn't tell what was in there.
A little quality time with a small wire brush and its back in good shape.
The toughest part was trying to hold down the spring while sliding out the ears that catch in the tank.
I ended up using 2 small c clamps with a block of wood between to keep them separated.
Some pics:

Goodysnap · Post by **Goodysnap** » Tue Apr 20, 2010 7:32 pm

You can also get em apart by applying compressed air to the vent hole on the gasket suface. (the little one that gets plugged up). Scared the crap out of me when it flew apart.

rustywrench · Post by **rustywrench** » Tue Apr 20, 2010 11:33 pm

You guys are funnier than a rubber crutch. I can just see Goody's face when it came apart.
I didn't have to deal with that much rust but I do have one that I will eventually some day. Glad to hear you got some good use out of my experiences.
As I told Jensen, the one thing I don't like is the low profile design of these caps. I may even in the future go to a more modern type ,maybe even one with raised parts to hang on to for open/close. Sure would save on the paint. Ride hard,,,,,,,,,,,,,,,,,,,,,,RW

brewsky · Post by **brewsky** » Wed Apr 21, 2010 5:25 am

Goodysnap wrote:You can also get em apart by applying compressed air to the vent hole on the gasket suface. (the little one that gets plugged up). Scared the crap out of me when it flew apart.

I use compressed air as a last result now......after about taking a finger off while blowing a piston out of a brake caliper!

Vince Lupo · Post by **Vince Lupo** » Wed Apr 21, 2010 5:06 pm

Very very interesting indeed. Here is a question though: As far as the 'wetness' of the gasket goes, is it the gas sloshing about and coming up through the middle of the cap and down through that little hole, or is it leaking through the seal between the gasket and the lip of the tank?

And you know I ride hard.....

brewsky · Post by **brewsky** » Wed Apr 21, 2010 6:48 pm

Every time I remove my cap, even with my new raised dome cap, there is gas on the gasket surface, and it usually spreads a little to the paint area.
For the gas from the tank to reach the outside of the gasket surface at the paint with the cap on, the gas would have to move up through the center hole, then up again through the hole in the rubber insert, then through one of the 2 holes in the small metal cap which inserts in the rubber insert, then through one of the 2 holes in the outside of the bottom portion of the cap........whew!
Or.....there could be a bad seal of the tank gasket itself.
Since I don't fill my tank completely full, or thrash the Dream around that much, I don't think any gas is coming thru the vent mechanism, but the gasket is still wet when I remove it.
I think its just surface tension causing the gas to spread when the cap is removed.
I haven't really tried to make it leak while the cap is on, but I will now just out of curiosity.

Goodysnap · Post by **Goodysnap** » Wed Apr 21, 2010 7:04 pm

I was'nt attempting to take my cap apart intentionally . I was checking the vent to be clear and squeezed a tad hard on the blow nozzle. I thought I had ruined it, but instead cleaned er out and put it back together. I also have been noticing the gasket wet but no external leaks, running mostly full tank more than empty. I'd dare say chalk this one up as a normal condition?