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Tip: Fuel Cap mods

rocketbob

rocketbob

Well Known Member
Often I find it fascinating how creative people can get in solving problems but overlook the obvious. Seeing how creative people can get in coming up with CNC machined levers to open fuel caps, and not fixing a simple geometry problem, is one of those things. The following mod takes about 5 minutes to do with a scotchbrite wheel. It will allow you to easily open your caps with a fingernail--no fancy schmantzy tools required!


Step 1. Disassemble the cap. Remove the locknut, and unscrew the bottom piece, and pull the lever assembly out of the fuel cap casting.
P1020946.JPGk



Step 2. Using your scotchbrite wheel, cut a negative rake aft of the pivot axis, with the forward end just slightly forward of the pivot pin. Then carefully smooth the radius forward of that. It doesn't take much! The angle is exaggerated with the red lines for illustrative purposes.
P1020950.JPG



When you're done you want it to look like this. The negative rake angle and the larger radius working against the wear plate make the cap much easier to operate. It makes the cap snap shut but at the same time makes it easy enough to operate that the cap opens easily with a fingernail. The key is to not overtighten the cap. It does not have to be air tight to keep fuel in and water out. In 11 years of flying my RV and leaving it outside many times in the rain, I never once saw any water in the fuel samples.

P1020953.JPG
 
Bob, This is great.

I did the mode last night on my scotch brite wheel. It took all of five minutes and results are great.

It is so simple.

What else don't I know?:eek:


Kent
 
Kent, you may or may not know this but Jeff Vaughn recently taught this to me. After you raise the fuel cap lever, push straight down on that lever and it will then relieve the seal so you wont have to struggle to remove the cap. Before knowing this I was wiggling/twisting the cap to release it!

I like the scotchbrite idea. Might have to give it a go!
 
The fact that it takes a little something to open other than a finger is a slight deterrent against little fingers at an airshow opening the cap. Perhaps a slight deterrent from a 6 year old opening the cap and putting something in the tank. Of course locking caps are better; short of that I would leave the cap unmodified.
 
asav8tor said:
The fact that it takes a little something to open other than a finger is a slight deterrent against little fingers at an airshow opening the cap. Perhaps a slight deterrent from a 6 year old opening the cap and putting something in the tank. Of course locking caps are better; short of that I would leave the cap unmodified.
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Using that logic, we should all be flying high-wing airplanes to prevent children from climbing on them. :)
 
Better make sure Van doesn't read this post or you might get mentioned by name in his next safety post! :p


Disclaimer: This post is intended to be funny. I am an engineer, so I fail in this type of endeavor quite often. I apologize in advance if I offend anyone here.:eek:
 
tkatc said:
Kent, you may or may not know this but Jeff Vaughn recently taught this to me. After you raise the fuel cap lever, push straight down on that lever and it will then relieve the seal so you wont have to struggle to remove the cap. Before knowing this I was wiggling/twisting the cap to release it!

I like the scotchbrite idea. Might have to give it a go!
Click to expand...

You can just lubricate and adjust the stock cap and it will work just fine without grinding anything off. Just try it first. The nut is a lock nut. back it off and spin the disc out to make the lever easer to work. Lube the O-ring first, then adjust so the cap will drop into the neck with a little resistance.

Pushing down on the lever to relieve the seal as mentioned above means that the O-ring can't slide on the taper and it needs to be lubed.

Why is it so hard for people to understand? Just remove a cap and look how it operates................ you will then understand that the O-ring MUST slide on the taper (requiring lube) or you will have a hard time removing and installing the cap. And you will stress the hinge pin and break it.
 
gasman said:
Pushing down on the lever to relieve the seal as mentioned above means that the O-ring can't slide on the taper and it needs to be lubed.

.
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Gasman, I agree. Its not rocket(bob) science. :). When you close the cap, the lever makes the o-ring bulge, creating the seal. While lube will help relieve the seal upon opening, my tip just helps the o-ring relax even more and it is easier to remove the cap.
 
664781 said:
Lube the o-rings about every other month with LPS4 and it will make a big difference.
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My first application of EZ-TURN fuel lube has lasted four years so far. But, I hear in really cold weather it will get sluggish ............:eek:

The caps come from USHER with EZ-TURN on the o-rings. Having the instructions for the cap would help you properly maintain the cap in good working order.........

USHER ENTERPRISES phone # is 503-992-0015
 
RV Fuel Cap

Just bought an extra fuel cap. Good idea for all RV drivers.

Most everything can be improved. Thanks for the tip Bob.

May try the mod on my spare cap to try out.

I will re-lube the large and small O-rings and adjust the nut as needed.

It has been noted that the roll pins give out, especially when the nut is over-tightened. I think it would be wise to get extra roll pins and/or an extra cap.
 
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