Need advice how to remove broken fuel bowl stub from Farmall gas tank

[sixdogs]

I have a Farmall C tractor with a leaking fuel bowl on the gas tank. It's just pot metal and when I tried to tighten it, the metal unit broke into pieces. No big deal but the threaded pot metal stub is broken off into the tank and I'm not sure how to remove it.

I tried an easy out but not even a budge. My plan now is to fill the tank with water to reduce fumes and think of some way to get that pot metal stub out. I probably did this when I was a kid but it's been decades and I'm a lot more careful now. The easy out just seems to force the pot metal to expand into the hole--or at least that what I'm thinking.

If it hadn't had gas in it I would drill it out and then easy-out the thin piece that remained. But that gas...

Any advice on how to get that stub out?

 

[Williy]

Is it possible to fill tank full of soapy water and gently
tap it out with a hammer and chisel?? like tap it
so it unscrews???

willy

 

[jaxs]

I think you are on the right path,esp getting fumes out before risking a spark. I've found that cutting pipe in 4 places will often cause it to bust out when pressure is applied with ease out. You can buy fine tooth saber saw blade skinny enough to fit inside hole clamped in vice grips. After cutting,if there's enough exposed,hit the sections with a drift punch. Hopefully you have a 1/8 pipe tap to chase threads because pot metal usually leaves corrosion residue behind. PB Blaster or other solvent will penetrate better if fitting is warmed before applying.

 

[sixdogs]

Thank you Williy and jaxs.

I did the narrow chisel thing and chipped it out. For whatever reason, I could not budge it by tapping and had to just get a chunk out and then work the whole piece out. It never turned at all and sure was stuck.

The threads on one side the tank hole are a little damaged but I'll wait until the filter gets here to check threads and then chase them clean. I do fear the threads might have opened up a bit on the tank and hope this doesn't cause a leak.

My plan is to wrap the filter threads with tape and then find some sort of gas-resistant sealant to help prevent leaks. The tank is off the tractor so it will be easier. Any ideas of a gas resistant sealant that might help me seal it?

 

[jaxs]

I wouldn't get carried away with sealing threads while installing new filter. If conventional thread sealer or tape leaks I'd try Locktite Blue and if that leaks it's time for permanent 2 part epoxy.

 

[rScotty]

Hello SixDogs.... You are on the right track with the sealant. I don't know if tape will help. The problem of a leaky fuel tank valve was epidemic in vintage tractors and motorcycles 50 years ago. At the repair shop the mechanics were always dealing with them.

Bikes and tractors both use gravity fuel feed instead of a fuel pump, and that means old farm tractors and motorcycles have to have a fuel tank above the carb and that tank had to have an outlet on the bottom. Add engine heat and vibration and that's pretty much a recipe for leakage.

A gas tap like that really ought to have been welded into place and then left alone, but manufacturers didn't seem to be capable of doing that. Instead, they complicated the
problem by theading the tap into the tank and then hanging an an on/off lever and sometimes a crud filtering system onto it.

So the sealer you want needs to be able to be easily applied and removed because you know there is a chance you are going to have to take that tap off to work on some part of it someday again.
In addition to being easy to remove, the sealant has to resist gasoline, and stay flexible either forever - or at least long enough to deal with being tightened occasionally, stay sealed under constant vibration, be easy to deal with removal/repair, and all the time have enough elasticity to deal with the internal pressure and thermal expansion without flowing out of the joint..

You basically want something that goes on as easy enough to flow and follow threads, but which cures overnight into a thickened flexible material that has good adhesion to metals....and then stays that way for years or maybe decades....

The rigid permanent epoxies fail on several of those requirements. Some gasket sealers like the RTV and silicons stay flexible, but most are not long term fuel and alcohol resistant.
But there is an answer.

The "go to" goo for gas tap threads is Hylomar Universal Blue - it's an aviation product, but you can find it online. Get the old style formulation. I've used it many times.

Hylomar - Home

Hylomar Ltd manufactures a wide range of high performance sealants and adhesives used by many of the leading OEM’s in the world of automotive, aerospace, white goods, power generation/distribution, electronics/photonics and general engineering.

hylomar.com

There are three Permatex products that seem to be chemically similar to Hylomar and now that 50 years have passed they might even be better. But I don't have experience with any of these Permatex products myself. I'd want to run a few basic experiments just to convince myself they are good.
They are:
Permatex 80017 Aviation Form a Gasket
Permatex 85420 Orange Permashield
Permatex 80057 300 Form a Gasket

Good luck with your Farmall. I've got to replace/rebuild the gas tap on our old John Deere this fall myself. Cork gaskets don't last forever. So I'll be using one of those products myself - and hoping I can get that pot metal assembly out and back in without it cracking.

rScotty

 

[sixdogs]

I'm the OP on this and here's how it ended. The fuel bowl was made of pot metal and that presumably made it non-sparking. Even so, I filled the fuel tank with water, let it dry in the sun for a day and then rinsed it again. I got a narrow chisel and punched at the remaining threads until they broke out and fell into the tub. I vacuumed them out and blew out the tank with 170 psi air pressure.

The threads were modestly bunged up so I chased them out and wrapped the threads on the new fuel bowl with extra thick teflon tape. Pic below. It's made for nat gas and propane lines or anything where extra sealing is needed. It's many times thicker that regular teflon tape.

I used the tape as plan A and if that failed was going to use one of the Permatex sealers mentioned by rScotty. That was plan B. If that failed, plan C was to get a stub brass MxF piece and epoxy it into the tank. Then I could run plumbing off of that. By the way, the tank thread was 3/8" NPT. That's pipe thread and not SAE machine threads. Anyway, Plan A worked and I'm back in business. Next year when the locals gather for the 10 mile ride to breakfast I'll be willing and able.

Thank you all for steering me on this.