The Stovebolt Site Forums The Shop Area Engine Shop New gas tank

Hi Stovebolters! I have a question. Just replaced the gas tank in my 49 chevy pick up. The shut off cock that threads into the bottom of the tank is leaking, and I can't seem to get it stopped. Here's what I think may be the problem. There was no problem with it tightening up and sealing in the old tank, because it had a small plate on the outside of the tank, and the small pipe coming out of the shut-off cock shouldered up against it, and tightend up and sealed. The new tank that I got from Chevy Duty has that plate welded/riveted inside the tank. So, the shut off valve isn't wanting to tighten up and seal. Any of you bolters replaced the seat tank with a new one? If so, what type of shut off cock did you use? The one I'm using is the one that was originaly on the truck.
Thanks for any advice.
KT
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1949 3/4 ton Chevy

In my 49 there is a small pipe nipple between the thank and the valve. I would go to the local ma and pa hardware and get a 2" brass nipple 1/4" pipe. You may need a union if the shut off valve is male thread and not female. I also used teflon tape on the pipe treads. Not on the flared fittings but the pipe threads. Hope this helps.

I just took my tank out and cleaned it. I had the petcock valve you describe and I couldn't find a new one that was similar. I took mine apart and cleaned it. Then I replaced the "O" ring that seals the shaft (valve). I put back the 2" tube and sealed everything up with teflon tape. Mine hasn't leaked so far. Hope this helps some.

First you need to determine exactly what is leaking, one of the joints or the valve itself.

If it's the valve, follow Michaels advice.

If it's the joint between the fitting or tube and the tank, you problem isn't as easy to repair. Pipe threads are tapered so that when you make a threaded joint the threads make the seal. If your fitting threads are bottoming out in the tank, call the vendor you bought the tank from and ask what to do, it sounds like the threads in the tank are not tapered.

I'm not a fan of using teflon tape on gasoline line joints. First, it doesn't seal real well, second a piece of the tape can come loose inside the fuel line. I now use the Permatex Hylomar sealant, developed by Rolls Royce for use in carbs. There are other gasoline resistant sealers out there, too.

Thanks to all who replied. I truly appreciate your input. Well, here is some more info. It seems that the plate that is riveted to the inside of the tank, surrounding the hole that the pipe nipple screws into is softer than the pipe nipple. If you ask me, it is a design flaw on this after market tank, along with the fact that on the original tank, the plate is on the outside of the tank which allows the nipple to tighten & seal up. I took the tank out and threaded the shut off valve / nipple into the tank to see if it would tighten up, and seal since it wouldn't be hitting on the bottom of the cab. Well, it stripped out. The metal plate shouldn't be softer metal than the pipe nipple. Also, another design flaw is that the vent pipe that runs along the fill tube comes up along the fill tube, and then makes a bend to the left. This forces you to make an S out of the rubber hose that connects it to the tube that comes out of the cab. I'm going to call Chevy Duty and see if they will do anything about the tank. If not, I'm going to have someone braze the pipe nipple into the bottom of the tank.
KT
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1949 3/4 ton Chevy

KT,
I am having the same exact problem with the pipe nipple on my new Chevy Duty '52 PU tank. I used teflon tape and it still leaks. Did you come up with any creative solution yet?

shoeless

Hi Shoeless. Well, I guess you could say I came up w/something creative! The new tanks from Chevy Duty have 2 design flaws, with the area where the pipe nipple threads in being one of them. I took the tank back to Chevy Duty, showed them the problem, and they gladly refunded my money. I then ordered a tank clean & seal kit from Eastwood, and cleaned & sealed my original tank. The tank was good, but when I first steamed it out, it rusted. If I would have had any idea that it would have rusted, and contaminated the fuel system, I would have sealed it at that time. Anyway, it seems to be ok now. No more problems.
KT
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1949 3/4 ton Chevy

im not taking chances im having a new one made out of aluminum for behind my seat

Guys please don't use teflon tape....Loctite PST is so much better
I've had to rebuild engines with tape in them don't get in the habit of using that stuff