Need tips about removing gas cap

[James the III]

take key out, whack the cap with a rubber mallet.. to get it on straight then put key back and take off cap.. easy.. years of working a station, have had to do this many times..
not the caps fault.. user error most times

[Billhilly]

I still like the rubber mallet idea, but as you've already tried that.....
I had a different situation where I couldn't get the cap the latch on, got a second slightly different one and had the same problem and ended up smacking it with my fist. That did it! Then I couldn't get it off! Turns out the lip just inside the filler neck was rolled away and the locking tabs had nowhere to lock. I ended up using a slide hammer to bring things back square inside the filler neck. It's possible the inside edge has been damaged (pump nozzle?) and now's it's caught/bound up. Bigger rubber hammer? The key operated ears on my one are very positive. When you turn the key you can't hold them. So unless there was a complete breakdown internally, if the key is turning and springing back is indicating it 'should' be functioning properly. Weird.

[Tdrcreyn4]

Use a slide hammer on the lock cylinder then you will have access to the locking tabs.

[El Dorado Jim]

I wouldnt have a drill anywhere near the filler neck of a gastank , the fumes are what ignite,rechargeable drills and electric corded drills have brushes that make sparks...

[Ironhorse]

Not sure these will help as both are totally different style of locks. The Atlas lock I have no idea where it came from or what it fits. Seems things just "appear" when playing with old cars and trucks as I have for many years.

The Atlas has "Fuel Emission Control Cap" at the top and "Pressure and Vacuum" at the bottom with the #s -- 24/671024 . A Google search found it on Ebay but did not say what it fit.

The second gas cap is one I had on my '71 4x4 in-cab gas tank before I moved to under the bed tank. Used it for many years with no problem but was always
pretty cautious about lubing with graphite.

Not much help but best I can do. Good luck with your problem.

[dmjlambert]

Thanks everybody. It warmed up enough today to be out in the sun, and I have removed it. After trying pressing, hitting with mallet, prying, and other non-destructive things suggested, I went ahead and destroyed it.

My method was using channel lock pliers to peel off the sheet metal cover. That was somewhat easy. Then I could fold back the rubber gasket to see what was actually going on. I found design defects in the cap.

As BILT4ME talks about in his post, the cap has two guides that slide into the two cutouts in the neck. Then 90 degrees to that, the two retractable ears lock under the lip inside the neck.

In this case, somebody either bumped into the cap in a parking lot, or attempted to take the cap off, or otherwise messed with it.

What happened is at the end of the two guides, there is NOT a solid ring of metal, which it would have if designed properly. There is nothing to keep the cap from being pushed hard enough to make those guides go into the neck of the tank, and if the cap is rotated, you end up having the guides AND the retractable ears holding the cap on. After seeing what was going on, I rotated the cap enough for the guides to line up with the cutouts, and then I unlocked it. I put a hose clamp on the rubber gasket to hold the cap together and use while I shop for a better cap.

Design defect number two is the rubber gasket is significantly deteriorated after just a year of use. Obviously it is made out of inappropriate materials for modern gasoline.

[dmjlambert]

The guides where way past the cutouts on the neck, completely hidden, not turned just slightly beyond the cutouts as I show in the picture. I am thinking somebody was seriously twisting on and messing with my gas cap.

[weq92f]

Probably a good thing it was on there then! There are only a couple reasons somebody would do that...

1) steal your gas
2) contaminate your gas

Either way, I would go back with another locking design.

-klb

[Billhilly]

Great you got it off!
I was thinking our caps must be different to allow this to happen, but it is your tank neck. Specifically, the cutout's that allow the fixed guides to drop in are wider, allowing the 'NOT a solid ring of metal' to drop below the sealing lip giving you the situation you've just encountered. If you look at my pictures you can see the cutout in my OE tank is just wide enough for the guides.
I'm wondering if you can help me with one other thing.
As I mentioned I ended up with two different caps, both of which are listed for this application. One is a #10491 which Stant call a 'vented anti-surge', which appears to be good 68-72, and a #10582 which they call 'emission control' specific to '71. Unfortunately I can't recall which number goes with which cap. But the crux of it is I have one cap that leaks like a sieve (when the tank is full), breathes very well! And the other seals up tight, but funnily enough doesn't breath at all (the emissions control one presumably). So two for two, neither usable really. How did your cap behave? Have you still got the paper work that identifies what it was?

[dmjlambert]

My Stant cap was part number ST10491, and it was supposedly vented. It did not seal tight as it should have, but it worked. I think a vented cap should seal tight, and it should have a 2 way valve in it that allows air in, and only allows air out if excessive pressure. So, a semi-one way air valve.
That is interesting about the cutout widths. So perhaps the original tank would be fine with the cap as designed, but in order for it to work with a variety of tank necks, a solid ring that goes all the way around the cap would not only prevent the problem, but also prevent tilting of the cap.
I love this forum, lots of good info and the pictures do help quite a bit.

[dmjlambert]

So, my tank has a design defect, the cutouts are too wide. And the cap has a design defect of the rubber not being the right type to work with modern gas. And the cap does not have flexibility of design to work with slightly different tank necks, not an outright design defect there, but should be improved.

[Billhilly]

Ok, well on my tank with the 10491 and parking on an angle after just filling up the petrol literally pours out! Not a good look. I agree with you. I'm looking for a cap that seals tight, and releases excessive pressure. Not a big ask surely!
It would be interesting to get Classic Industries take on the matter..... And yes, the cap is close, but not quite right. Want to ring Stant for us?

[dmjlambert]

Thank you, good idea. I have contacted Stant and told of the difficulties, and asked them to view this discussion, and join in the discussion if they can. I think it would be great to see them use this large community as a source of information and feedback, and improve and customize the products to be suitable, and in fact superior.

[ctsandb]

When I was in college 30 years ago, I let some friends borrow my 69 to move some things to a city 2 hours away. I forgot to give them the key to the gas tank so they had to do like you did and tore the cap apart in order to add gas. Unfortunately, they lost grip of the cap when the too the outer piece off and it slid down into the tank.

I'm I embarrassed to say that I drove it like that, with the cap audibly rolling from side to side at every corner, until two summers ago. It was easy enough to get out when I took the tank out. I like to think that it kept any deposits from forming in the bottom of the tank over those many years!!

[dmjlambert]

Yes, a gas tank agitator to keep things stirred up. That would have agitated more than the tank, it would have driven me crazy.

Stant, for when you join this thread for discussion or your consideration, the ridge marked in red in this picture needs to be much wider or to go all the way around the cap. The size it is right now allows the cap to go too far down into the neck of some tanks or to fall down in the tank. And the rubber needs to be updated to withstand modern gas. And the key operated ears need to hold the cap tighter to prevent gas from spilling out. Perhaps those ears or tabs could have a depth adjustment added.

[garyd1961]

Originally Posted by weq92f

Probably a good thing it was on there then! There are only a couple reasons somebody would do that...

1) steal your gas
2) contaminate your gas

Either way, I would go back with another locking design.

-klb

Gas thieves love these old trucks, that's why I had to install a locking cap on my truck. I live out in the country and my truck sits 10 feet from my back door. At 4 am I caught two thieves stealing my gas. I won't say on here what I did but it involved my AK47 and my neighbors calling the police. I informed my neighbors what had happened and they informed the police who never spoke to me.
Anyway the thieves never came back, lol.