How To: Rebuild locking gas cap

This was originally posted on the old .COM site by JMLaux. I retrieved it from archive.org and am posting it verbatim, his words, photos and instructions. Thanks go to him for writing it in the first place.

Click the images for larger versions.


This How-to outlines the steps disassembling a locking gas cap for cleaning and lubricating.

Attachment 8546

Tools Required:

Small Punch
Hammer
Bench vice
Rag


Parts/Supplies Required:

Graphite lock lubricant
Safety Glasses (optional)
Silicon Spray (optional)
Brake Cleaner (optional)


Estimated Time for Completion: 15-30 minutes

Difficulty Level: Novice

Procedure:

Step 1:
Remove the gas cap from the tank.

Step 2:
Place the rag over the vice and put the cap in the vice. You may have to try different positions in the vice in order to get a good grip to remove the roll pin. Make sure you are careful you do not mar the surface of the cap with the vice jaw.

Step 3:
Once you have the cap secured in the vice, use your punch to hammer out the roll pin at the tip of the cap. Be careful with removing the pin so the cap does not come apart from the spring inside.

Attachment 8552

Step 4:
When the pin is out, remove the cap from the vice and remove each part of the cap. Take note on how each part goes together to ease in re assembly.

The order goes like this:

Black top cap
Attachment 8550

Spring
Attachment 8547


Nylon Locking Mechanism
Attachment 8548

Black Locking Mechanism Base
Attachment 8549

Cap Base with Rubber Washer
Attachment 8551

Step 5:
To take out the tumbler, I found it easiest to put the key in it first. That will hold all of the tabs in the tumbler so they do not come out. Once the key is in, push from the bottom to pull the tumbler out.

Step 6:
In the gas cap there is a rubber washer to seal the filler neck and a rubber o-ring to seal the bottom of the tumbler. Remove both of these and set them aside. The o-ring will either be on the tumbler bottom or if you look in the cap base you will see it inside.

Step 7: Clean everything with some dishwashing soap to get off the build up dirt.

If your tumbler is looking dirty go ahead and spray it out with brake cleaner to get out all the build up dirt. Make sure you keep the key in to prevent the tabs from falling out. You can also hold the tabs in place and remove the key to spray inside of the tumbler. Make sure you use safety glasses when you are spraying the brake cleaner or the estimated time will turn into about an hour because you have to flush out your eye.

Step 8:
Once everything is dry it is time for reassembly.

I usually spray the rubber with silicon and let it soak in to soften the rubber.

While the tumbler is out I put Graphite lock lubricant on the tabs and inside the key hole to lubricate it (shown in blue). I also put some of the graphite on a Q-Tip and swabbed the outside of the tumbler as well as the inside of the cap base where the tumbler goes.

I also put some dielectric grease (shown in red) where the O-ring would ride.

Attachment 8545

Step 9:
Put the O-ring back in the cap base and push it down to the bottom.

With the key in, slide the tumbler in the cap base and make sure the tumbler is in working order. Make sure the tumbler turns with the key in and will lock in place with the key out.

Step 10:
Make sure the rubber washer is placed back in the cap base and put in the Black Locking Mechanism Base. There is a groove that it slides in place with.

Put some lubricant on the surface where the Nylon Locking Mechanism rides on the Locking Mechanism Base. You can spray some silicon, or use a little bit of graphite. This will cut down on the friction and let the cap open easier.

Put the Nylon Locking Mechanism on its base and place it in the lock position as shown:

Attachment 8548

Step 11:
Place the spring on top of the Nylon Locking Mechanism and put the black cap on top of the spring.

Align the top cap so you can put the roll pin back through the hole. It is easier to hold it all together if you put it back in the vice jaws.

Step 12:
Hammer the pin back into the hole and test the cap to make sure it will lock and unlock like it should. Put the cap back on the tank.

Now you should be able to enjoy a locking gas cap for another 25 years.