In Reply to: Stopping fuel leaks at fittings posted by Jason (SWOR) on October 17, 2018 at 11:05:57:
Healing can be a long process. Just do what the doctor ordered.
For the Ford Tractor fuel system, best to use a part made for the job -see LINK below with the fuel line, exactly pre-bent steel line with correct fittings. Brake and fuel lines use a special thread size - 7/16-24. Many fellas muck them up by using the wrong tap or thread die to "fix" a part with and all it does is cross thread with the wrong pitch which in turn causes leaks. As mentioned, forget Teflon Tape or plumbing compound. You don't want to be guessing if fuel will leak or not do you? Always start the fittings by hand so you can get the 'feel' whether they are fastening correctly. Once you cross-thread a component, it is almost impossible to correct. The steel line use steel fittings, the sediment bulb uses a pewter or aluminum base. Steel is harder and thus it is the softer material that will get cross-threaded. Installation works best by using two hands. One to gently wiggle the line as you work to ensure the flare is seating properly and aligning it squarely. Use the the other hand to slowly screw the fitting in. Never force it. If the line gets bent at the fitting and you try to straighten it, it can be a problem for leaks to occur so be gentle. On the Sediment Bulb Assembly, the line connects to the output port. The other end inserts into the brass elbow on the carb. Use a 7/6" Flare Nut Wrench to do the final tightening and do not overtighten. Often times leaks are the result of the Sediment Bulb Valve Stem. There is a rubber seal, some new units use vinyl, on the stem that will eventually wear out, get torn, and thus leak. Sometimes leaks are coming from it and misdiagnosed as being a bad connection elsewhere. The valve stem is a $5 part. It is the only wear part on the assembly. You don't need to buy a whole new assembly when repairing them. The stem uses the same size thread into the bulb base as the fuel line. Get a new valve stem and a new cork gasket and brass screen for the jar when doing PM. The stem is p/n APN-9194 and comes with a new knurled knob, 8-32 screw, and #8 star lockwasher. I always put a dab of Loctite on the screw to ensure it never comes off the assembly in the field. You never need to take it off either until the next valve stem replacement. Then there is a fine thread sealant product called E-SEAL made by GASOILA. I use it ONLY on the sediment bulb screwing into the gas tank. The tank and all parts must be dry when you apply it. Assemble and let stand for few days before using. I only use it because I had once bought a cheap aftermarket assembly with the WRONG NPT threads on it and it mucked up my gas tank inlet. Not everyone needs to use a sealant on the bulb to the tank. I will also use it when I work on someone's tractor and they want a new bulb installed. I NEVER use anything on fuel lines elsewhere. Always use the correct 1/4" steel brake/fuel lines. Never use copper, nylon, plastic, or aluminum. This procedure is what I've developed over my years working on N's.
FORD TRACTOR FUEL SEDIMENT BULB ASSEMBLY:
SEDIMENT BULB VALVE STEM :
E-SEAL BY GASOILA –THREAD SEALING COMPOUND: