The joint between the tank & fitting that the sediment bowl screws into on my '26 touring gas tank has a very small leak. Not enough to really drip, but enough to always be wet & smelly. I'd like to fix this before warm weather returns. I've read the removal directions in the service book....do you really have to loosen the brake & reverse pedal adjustments to get enough clearance to get the tank out??
Also, regarding fixing the leak, I hate to have the tank coated on the inside, as it is a very nice tank with no rust or gunk at all on the inside (from what I can see with an extended mini flashlight(explosion proof, btw). Anyone know if the fitting can just be soldered to the tank?
Mike -- You can drain the tank, clean that area really well with some lacquer thinner, then patch it from the outside using JB Weld. Use the original, not the quick-setting kind.
Are you sure its the fitting? The threaded connection on my 27 dripped and I sealed it with No. 2 Permatex.
Someone in the past used some brand of thread sealer that prevented the sediment bowl from fully seating inside the tank connection.
Used a tap to clean up the threads. Sediment bowl now seats correctly without leaks. Used the yellow teflon tape as "insurance".
1/2 " pipe tap, same as the spark plug !
Please remember that pipe threads are tapered. Just run the tap up enough to clean up the threads. If you run a pipe tap all the way up the threads will be oversized and leak like crazy.
Not really Paul, the pipe threads are tapered, so the sediment bowl threads will take a few more turns to seat in the tank fiting.
I respectively disagree. Run a 1/2 inch pipe tap all the way through the spark plug threads of a T head and see it the spark plugs will seal.
Taking the tank out isn't as big a job as it looks.
Yes, you have disconnect the brake pedal but you don't have to take it completely out. Before you do anything, fill the trans with rags, push the brake pedal down and wire the band (and the spring) in place, then remove the adjustment nut and washer. Just slide the pedal out far enough so you can rotate it down, out of the way.
I disconnected the battery and removed the instrument panel as well. I replaced the (rock hard) fabric on the straps and inside the cowl with rubber strips while I was in there.
Yes, the leak is where the cast fitting is riveted onto the tank. I have been using a newer sediment bowl/shut off (with glass bowl) just to prove to myself it was the joint instead of the original style sediment bowl.
Bob, I partially agree, you don't want to run a NPT tap all the way thru something or you will oversize the hole. I work for company that made water pumps for cars & we tapped a lot of npt threads over the years. I don't know what Henry originally used on his gas tanks, but most fuel joints use a NPSI or NPSF thread, which is very similar to taper threads, but they are straight threads. The theory is that the tapered npt thread on the male part acts like a cork in a bottle (the taper male part tightens up into the straight female threaded hole).
Is JB Weld going to stand up to gas? I hate to slop a bunch of glue on it just to watch it turn gooey & still leak.
Yes, JB weld will stand up to gas.
I was able to remove the gas tank from my '26 coupe by simply pressing down on the pedal. Aluminum Devcon 2 part epoxy putty would be my choice (in the 1 lb. box), but nothing is going to work if you don't clean it super well. I repaired a crank case oil leak on my Troy bilt lawn mower 25 years ago with Aluminum Devcon and it has not leaked since. Not only has it stood up to the heat and vibration of a running engine, it has stood up to the petroleum distillates in the oil. Once mixed, it has the consistency of cake icing and is very easy to use and once it begins to firm up, you can use your wet inger to gently smooth the repair so that it is as smooth as glass. Jim Patrick
Jim, I figured since I had to take the tank out (mine was literally dripping on my feet), I might as well dry out the floor boards, wash the carpet, check the bands, change the oil, clean the screen, all the usual stuff, while I was at it. I moved my brake pedal down toward the rear of the car, to get it completely out of the way.
My original tank had some kind of cloth/tar coating on it. It was going to be necessary to remove the coating to find the leak but it was clear that it was at (or close to) the left side tank seam. I bought another tank on line and got lucky, it was almost like new. It didn't have that coating on it?
I was going to mention that the area around the fuel outlet is a stressed area, it has the load and the vibration of the fuel shut-off on it. So if you're going to coat it from the outside with some kind of sealer (JB Weld?), take a wire wheel in a drill and clean the area completely around the fitting and coat the whole thing, all the way around.
Dennis. I hope you plan to restore your original '26 cowl tank. Repros are not made and originals are pretty hard to come by and, once it has been cleaned of the exterior coating, cleaned on the inside, repaired and painted, you can sell it on ebay and recoup the cost of the replacement tank. Once cleaned, if you can solder or braze the leaks it will be much stronger than epoxy. Good luck and Happy New Year. Jim Patrick
FWIW- I think on new earlier tanks the vendors are "painting" the bung area ring and potato area ring with something like Devcon anyway...yeah, looks like solder, but without checking further, also looks like it was "painted" in place and not flowed
Others may pummel, but in the past on old tanks, I have had great success with what they call tank putty. It's cheap, you roll it like a worm, and press it in place like chewing gum. Do a fair cleaning first as prep, have never had a leaker after.
Oh, yes Jim. I've still got the original tank and I plan on repairing it.
Thanks for all the input. I'll be pulling the tank this weekend (I had already drained it, as it would just ooz out anyway if i'd left any fuel in it).
I think I'll take it to a local oil field repair / machine shop that's been in business a long time to get their opinions on the best approach. I've had them boil out gas tanks and braze up cracked cast iron parts for me in the past. They've got a history or working on odd things, so I'll compare their ideas to those posted here for the best plan.
I was just glad to learn that I could squeeze the tank out without having to loosen up the pedal adjustments. The tranny functions really well & I didn't want to monkey with it if I didn't have to.
Here is an interior view of the Improved Car gas cowl tank.
Rather complicated, that is why no repops.
The internal overflow tube is suspect too, if that gets pinholes, gas from the tank will leak right out, just like a drain. That happened on one of mine. To fix, used gas tank sealer in the overflow tube, corked both ends, then let it run back and forth as I tilted the tank. Several coats. That fixed it......
Another one had pinholes on the top, where the straps hold it down. My radiator shop fixed that with a patch panel. On another, with loose baffle, the shop declined, saying cost too much as the whole tank would have to come down, all joints un-soldered. But you can have a complete rebuild by one of the vendors, Texas T Parts. Nice to have a choice, but costs some $.
Most everybody on this forum seem to be negative on gas tank sealer.
Myself and my sons have used the sealer in many tanks. The tank has to be super cleaned first with acid or some cleaner that will remove most of the crude. A quart or more of the sealer is poured into the tank and slushed all around in an attemp to coat all of the inside. The excess is poured out and the tank is left to dry. If some larger leaks are not completely sealed, a second coating could be applied.
There was a variety of sealer some years back that would dissolve with the modern fuels and cause quite a mess.
The current sealer is great for sealing those leaky seams, pin holes and in general coating the tank preventing further rust.
We have this in at least 10 different fuel tanks and have no problems.
thanks for posting the picture. I didn't realize there was a 2nd baffle inside. I think my first choice on a fix is to solder the fitting, but don't know if the heat will cause thegasket to overheat & keep the solder from spoiling the joint. I'll wait until I confer with the machine shop before acting.
I just re-read the whole string & noticed Dennis's post about undoing the brake pedal. I guess it will boil down to if I hold my mouth right or not. I'll know in a day or two.
OK, here's the deal on the brake pedal. If Jim says the tank will come out without disconnecting the pedal it probably will. He knows a lot more about these cars than I do. But it seems to me that you're going to at least have to find a way to keep the pedal out of your way, like wiring it in the "applying the brakes" position. Maybe Jim will give you some pointers on that.