Gas Tank Drain

[MGG]

I have a 1934 truck which I do not drive very often. It has the original gas tank with multiple baffles. I would like to occasionally drain out the old gas and put in new. Does anyone have a recommendation/procedure for where or if I could install a drain valve? I do not want to siphon or disconnect the line from the valve at the tank for fear of eventually creating a leak there. Siphoning does not work very well because of the baffles. Thanks

[Lawson Cox]

Isn't there a drain hole already in the tank, fitted with a screw to prevent leaking?? You should be able to put a petcock in in place of the screw.

Baffles are to keep gas from sloshing around in tank, they do not separate tank into several leak-proof sections. There are openings around baffles to let gas move between baffles. Baffles should not interfere with a siphon hose.

Use a siphon pump and not your mouth.

[MGG]

There is no drain hole. There is a large hole where the gas gauge sending unit bolts in with 6 bolts and a smaller hole where the fuel line connects. I will try the siphon pump again. Thanks

[G.M.]

All of the old ford tanks I have seen had drain plugs in the bottom. The plug is a 1/4" pipe hole and the original pugs have a screw driver slot to remove them. Most are hard to get out. I had several about 2 months ago with good slots I even made some deeper and wider to get a wide blade brand new with a hex shaft blade that fit tight into the slot. I used a small power bar handle to turn it with a block of wood on the floor jack pushing the blade up into the slot. The jack lifted the body and frame up on the springs but couldn't get the blade to stay in the slot. Wound up drilling three out.
Started with a small drill the width of the slot so the drill would stay in the center. Went up in drill size for a large EZ out. Got lucky and all three were dead center and came out with no thread damage. Put regular pipe plugs back in with the square wrench stud. These drains sit in a little depression at the lowest spot of the bottom.
G.M.

[DavidG]

There's no drain plug on a '32-'34 big truck tank; the same goes for all '32 commercial vehicle tanks except that of the sedan delivery. Those are all cab mounted tanks and have just the sending units and outlets with a shutoff valve in the bottom of the tank, as stated above.

[Lawson Cox]

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Originally Posted by DavidG

There's no drain plug on a '32-'34 big truck tank; the same goes for all '32 commercial vehicle tanks except that of the sedan delivery. Those are all cab mounted tanks and have just the sending units and outlets with a shutoff valve in the bottom of the tank, as stated above.

Well, I do declare!!! Who would 'a thunk it??

[JM 35 Sedan]

I have several '35 gas tanks that I have not been able to remove that slotted head plug on. I used a hand held impact driver with a flat blade screwdriver bit attached and could not remove them even after soaking with penitrating oil for days. Didn't care to use heat (kaboom!!) or drill holes, so just left them in place.

[MGG]

Originally Posted by MGG

I have a 1934 truck which I do not drive very often. It has the original gas tank with multiple baffles. I would like to occasionally drain out the old gas and put in new. Does anyone have a recommendation/procedure for where or if I could install a drain valve? I do not want to siphon or disconnect the line from the valve at the tank for fear of eventually creating a leak there. Siphoning does not work very well because of the baffles. Thanks

Mine is as DavidG says, a 1934 BB dump truck with the tank under the seat. I wish now that I would have put a drain plug in when I had the tank out for cleaning. I don't want to take it out again. I may try to remove and tap a clear spot in the plate which holds the sending unit apparatus if siphoning becomes too much of a hassle. Thanks everyone for all of the tips.

[DavidG]

Be super careful if you drill a hole as a spark can blow the tank and everything around it to smithereens.

[MGG]

I would remove it from the tank and do the job on my work bench with no trace of gasoline or vapors present. Also, I would not do anything which would render the sending unit useless because the original gas gauge and windshield wiper are the last items I do not yet have working.

[rbullockv8]

Originally Posted by MGG

I would remove it from the tank and do the job on my work bench with no trace of gasoline or vapors present. Also, I would not do anything which would render the sending unit useless because the original gas gauge and windshield wiper are the last items I do not yet have working.

I have a 32 pickup--same setup as yours. Clean tank with new gasket on sending unit. I'm getting some leaking from the sending unit area. The truck isn't drivable yet, but I put in a couple of gallons to start it. Trying to isolate the leak. If I don't have the air line hooked up, is there anything that can leak out of the sender other than at gasket? I didn't put any sealer on the gasket yet.

[scooder]

It's got a tap on the bottom, I believe your making hard work for yourself. Can you not just turn the tap off, disconnect the line from the tap, and turn the tap on and drain?
Got to be the easiest way.
Martin.

[G.M.]

Originally Posted by DavidG

There's no drain plug on a '32-'34 big truck tank; the same goes for all '32 commercial vehicle tanks except that of the sedan delivery. Those are all cab mounted tanks and have just the sending units and outlets with a shutoff valve in the bottom of the tank, as stated above.

I forgot about the bottom mounted sender. I just drained my 32 woody a few months ago and forgot about the drain. Mine has a "T" at the shut off with a drain valve in the "T". I drained 7 or 8 32 to 39's and the woody wasn't a problem and I forgot it. The sender in the commercial bodies is made upside down. The little brass gas catching cups are upside down compared to the car senders. G.M.

[D. Jones]

Even an apparently dry gas tank may have fumes. If you intend to use any flame near or on one here's how the commercial welders do it. Drain the tank then fill it with CO2 either from an extinguisher or by putting dry ice in it and letting the dry ice fume off for a while. The CO2 displaces any gas fumes and the O2 from the tank and wont harm the tank.

[DavidG]

Scooder hit the nail on the head. It is so obvious that it is not obvious. I did exactly that when I last drained the tank in my avatar wagon, but that was a while ago and what I did evidently had fallen off my radar screen.

[MGG]

Originally Posted by MGG

I have a 1934 truck which I do not drive very often. It has the original gas tank with multiple baffles. I would like to occasionally drain out the old gas and put in new. Does anyone have a recommendation/procedure for where or if I could install a drain valve? I do not want to siphon or disconnect the line from the valve at the tank for fear of eventually creating a leak there. Siphoning does not work very well because of the baffles. Thanks

I fought with leakage from the valve and fuel line connection for a while and finally got it stopped with a new valve (made in who knows where). I really do not wish to work the valve too much or disconnect and reconnect the fuel line but maybe once more to install a tee or something, out of concern that doing that too many times may cause leakage again. Leaking gasoline below my seat makes me nervous.

Anything that I may do to the bottom mounted sending unit will be done off of the tank and far away from any gasoline or fumes. I can get it off the tank from the bottom without removing the tank or disconnecting the fuel line and with only a socket and no outside power source. I will try siphoning again with a different setup.

[1932BB]

Is your truck a 4 cylinder or an eight? The four can leak from the fuel pump (internally or externally) or the carb as the BB gas tank is mounted above the level of the pump and carb. I always turn off the gas when parked in the garage and I have had no trouble with an original valve. They are well built and have a packing nut.

[MGG]

Mine is a V-8. The tank is below the seat, well below the carb and fuel pump. the valve is down underneath and hard to get to unless I lay on my back and scoot under.