If you've done this what kind of material did you use. Keep in mind that I want to recycle the nuts & nipples to another member here. 14ga round blank, WWII steel penny???? TIA, Kent

just drill out the current outlet and tap with a pipe thread and install plugs.

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Nah, that's to easy. Great idea! Thx.

Do NOT weld a gas tank. . . gas residue permeates the metals pores and will ignite {AS in explode} when heated. . . There are methods to displace the air / oxygen in the tank to lessen [but not eliminate] the chance of combustion . . . i can't stress this enough. . Dangerous. .

I still have the scars from 40 years ago. .

Ouch! I gas welded a hole in an old dodge gas tank when I was a kid. It was still wet with gas from the day before so I filled it with water. Sure enough that small pocket of air, maybe a qt in volume, flashed. I can only imagine if I hadn't filled it 99% full of water. Thanks for the safety tip. BTW, how long do you think before it would quit out-gassing.

When I welded my tank I rinsed it with water, let it dry out for a few days and then put a vacuume on reverse with a hose all the way down inside to blow out the fumes while I welded it! No problems and no flash!

Tried welding like that thirty years ago, and I still remember the smell of the burnt eyebrows and hair from the flash. Never again!

The tapping and plugging seems the safest and best course, and can always be used as a drain for the tank.

Kent, I reused the old nut. I smoothed out both sides of a penny, (Foreign curacy of course) removed the nipple part and replaced it with the penny.
It's a block off plate with the same seal surface as the original outlet.

Put Dry Ice (carbon dioxide) in the tank to displace any air (oxygen) & weld away!

Good points about welding. Dry ice is smart. I was thinking about some 75/25 from the tank. It's been dry for over 9 months and has no smell. Mike, your tip is intriguing. It's a 12mm opening so I should be able to tap M14 1.5 and use oil pan plugs w/ alum crush washer. Thanks for all the good ideas & points.

I'm going to try to tap it first. Inside dimension is 12mm and an M14 1.5 needs 12.5mm drill size so this should work............ http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...atchlink:top:en
If not, it's welded shut. Chris was kind enough to offer a spare tank in case I this one up. so I'm feeling unusually confident.

Before you drill and remove metal permanently, measure the outside of the current neck at the smallest portion under the threads. . and think about how deep the new threads inside will cut into the metal. . . might be better to use an SAE and fine thread size for the plug. [1.5 mm is very coarse]

Remember it's not necessarily the threads that hold back the gas inside, its the head of the bolt where it seats on a soft washer at the neck. .

The other thing you can do is drop a bolt [with a copper washer on it] thru the inside and out the hole. . then put another copper washer on it and a nut and tighten. . the double copper washers will seal it, and there is no damage to the tank. .

I used this.

Andrew

Your right about the thread depth and thickness or thinness in this case. It was marginal to begin with but then I noticed that the nipples are actually smaller than I measured. I missed that the ID actually increases once inside because the ends are slightly flanged to accept the washer. Now I'm down to NASA tolerances plus I would be drilling free hand. The bolt thru idea would only work on the outlet opening. BTW, that opening is slightly beveled. The return is not accessible from inside. Good thought though. Thx for your insight. At this point I'm better off to just weld the end of the small tubes.


That looked great until I read the disclaimer for ethanol. It's all we can get in SoCal unless I drive over to the airfield. Why didn't they just use a fiber washer instead of that rubber O-ring.

We need a GB on a metric cap. Think it is 18mm x 1.5 ?
I looked all over couldn't find them.

Any machinist here that could make these? M18 1.0. I looked at McMaster but didn't find them. It seemed that the larger diameters e.g. 18mm have coarse thds.

EDIT: Maybe we could get Mark to make us some rubber caps. lol

Use the original actual cap, remove the tube, insert a lead washer. .
Done !!

+1

Hold 'er Newt. How do I seal the hole in the washer? It's a nut not a cap.

Ok I used the wrong word. . Insert a lead plate without a hole in in it. . or weld up the nut. .
P.S. this is what i did on mine. . Works great. . lead is softer and seals better. unless you can get true soft copper [no alloy added]

Call it a slug.

The threads on my tank were so messed up from removing the nuts, I just tapped the inside and installed a fitting. Works great and I think would be your best (easiest) option.

Good idea and even easier.

As discussed on the first page, I don't think mine has enough meat to safely tap. I would have appx 1.75mm wall thickness when finished. I'm beginning to wonder if there were different thicknesses used. Doesn't make sense from a mfg standpoint.

I ground down a slug and put a copper crush washer on the tank side to seal it, then the OEM fitting and tightened it . But a cap would have been nicer!

Thanks to all for the suggestions. I decided the smart thing was to pinch & weld the tube ends. It's thin material so I gas welded it. BTW, there's no welding these nuts closed. Not me anyway. They're non-ferous; 6061 T4 Aluminum or SS maybe? 2 styles of nuts possibly?

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