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What a revoltin' development...part III

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TR6BILL

Luke Skywalker
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I have a Moss aluminum gas tank in my car that I installed about 4 years ago, and have always smelled a little whiff of gasoline while driving. Finally, about a year ago, I pulled the forward trunk panel and discovered that there was a pretty evident gas stain around the cork gasket that seals my sending unit. Now, I sealed that gasket very well so I know this shouldn't be happening. Well, I went ahead an heavily coated the whole perimeter of the sending unit with Permatex Aviation and this stopped it. Anyway, since the gas tank is now out (didn't want to weld about gas lines for my suspension), figured this is a good time to change out the sending unit anyway; the old new unit was never accurate. Bought a new unit with new screws (6) and gasket. What do I find but two of the #10 - 32 screws were stripped in the aluminum. That is why my seal never sealed. Again, very fine thread in very soft aluminum is not a good mix. I retapped all 6 holes and went oversize to #12 - 24 thread screws and rubber sealing washers on each screw. A real PITA but gotta do it. And had to drill out my new sending unit flange to accept the new larger screw. Will place them with some sealer on the threads as well.

It never ends....
 
If you haven't yet drilled out the sender unit...

Then read on, if you have, then neeeever mind.

I would seriously look into drilling out the sender mounting holes and putting helicoils in them. Either fine or coarse thread. Put the coils in with locktite, I usually use, I think the number is 624, which is a retaining compound, rather than a threadlocker. Let the compound set for a day or two, Then, while you can still reach through the hole for the sender, use gas tank epoxy on the INSIDE of the tank to seal the gas side of the screws, While the expoxy is still somewhat pliable, use screws that do not stick too more than a thread or two into the tank. The less the better.

I gotta dollar that the 12/24 tap you ran through, is the perfect size for a 10/24 helicoil.

FWIW
 
Thanks for the tip, Steve. Done deal though. I will find a sealing compound for the screws. Those silly fiber washers Moss sent were darn fragile. 2 of the broke, even with the smaller screws. Frustratin'.
 
Bill.... while you have the sending unit out, you might want to replace the float with a brass Mustang float. The plastic ones always slowly absorb and fill with gas. $10 at MustangsUnlimited.com

Float2.jpg


I also advice against using the rubber baffle on the float as they can come loose, breakdown in the gas and eventually clog your tank outlet..... Ask me how I know.

Tow1.jpg
 
We used to seal wing tanks on airplanes with this two part nasty stuff. Worked though. It was strong enough that they glued airplanes together with it. The Grumman Cheetah's and Tiger's to be exact.

Wish I could get ahold of some of that stuff now.

I wonder if nylon washers would work on those screws?
 
I dunno. I am thinking of coating the threads of the little screws with some Locktite sealing compound and then going over each seated head with a nice glob of Form-A-Gasket Aviation and let it firm up. That way I can snug the screws down good and tight.

A new problem with my Moss (at least they sold it) aluminum tank, one of the 6 mounting tabs is cracked. Phooey. Now I have to wait for the aluminum welder to open shop Monday.
 
Closer inspection of the mounting tabs show that 4 of the six tabs are dangerously cracked! I'm callin Moss in the morning! The only reason the top tabs didn't crack is they are double thick. This is definitely a very poor design.....Wouldn't recommend them to anyone. I don't think Moss makes these, they just sell them. I will find out, with some digging, who the manufacturer is! :madder:
 
That's all you need is to have a gas tank flopping about without being tied down. Yikes.
 
TR6BILL said:
Closer inspection of the mounting tabs show that 4 of the six tabs are dangerously cracked! I'm callin Moss in the morning! The only reason the top tabs didn't crack is they are double thick. This is definitely a very poor design.....Wouldn't recommend them to anyone. I don't think Moss makes these, they just sell them. I will find out, with some digging, who the manufacturer is! :madder:
Click to expand...


My Bad! It was not Moss that I bought it from but TRF. Moss doesn't even sell these tanks. I called TRF and alerted them to the possibility that this may happen. Didn't realize that I had bought the tank 7 years ago! My how time flies. Found an aluminum welder that will reinforce it for me. Sorry, Moss....
 
Oh no! I have nightmares about that movie. And a bottle and a spare bottle of clove oil in my medicine cabinet. I couldn't watch it again, it's safe to say.
 
Yes that happened to the rubber baffle on my float. It just stretched and fell off. Why such cheap material. The original lasted 40 years, and my new one lasted 6 months.
 
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