Fuel valve woes continue

[Jeffbo1]

I removed and dismantled my plug type original wing tank fuel transfer valves, cleaned and installed o-rings....re-installed and added 5 gallons to each wing tank...valves held for 48 hours but upon turning them on, the left valve began leaking worse than it ever had...now i'm stumped and can't fly, is there any alternative to these valves or a service that can properly rebuild them? I'd hate to cork off my wing tanks to fly off only the header...any thoughts would be much appreciated...

Jeff

[Robert Lees]

Re: Fuel valve woes continue

Did you lap the valve when you had it apart?

Can you tighten the cap a bit? (I seem to recall there are shims in there to take up wear on the taper).

[Jeffbo1]

Re: Fuel valve woes continue

Hi Robert...I did some fine polishing of the cone and cup but not as much as i should have...the caps each have a thin copper compression washer underneath and to be truthful the right valve worked well while the left one leaked. upon removing the left valve i was able to tighten the cap a small amount...i may pull them both and lap them properly then make sure they are good and tight....my only other option is to buy a pair of 1.5 inch valves with 3/8th inch female fittings from wicks...they are smaller and would require plumbing parts but should ultimately work...i don't know...very frustrating..thanks again!

jeff

[Ragwing nut]

Re: Fuel valve woes continue

What are they leaking past, the shaft or threads? The shaft should have a packing, not an o-ring. O-ring sometimes work, but not always

[Forrest Barber]

Re: Fuel valve woes continue

correct, no o-rings , leather packing OR I have wound rib stitch cord around the shaft as a temporary fix and some last 10 years.

[Robert Lees]

Re: Fuel valve woes continue

Jeff, if you try lapping, use the finest lapping paste you can find.

The finest I know is toothpaste. Then the even finest I know is mayonnaise (get a big jar, use a small bit at a time, replace it often and be prepared for a few hours to show the difference!)

Commercially-available lapping compound (like valve-lapping compound) is too coarse, unless there is visible scoring on the faces.

[Jeffbo1]

Re: Fuel valve woes continue

Thank you all, i bought a set of punches and will try to make leather packing, it seemed to be leaking past the the shaft below the handle mostly...as far as holding back fuel from the header, both valves seem fine in this regard, just the left valve was actually leaking from the shaft and or the cap below the handle...i will post updates as i go along and hopefully will cure this...thank you for the tip Robert on toothpaste, hadn't thought of that...i also have some 1200 grit polishing powder that i was going to mix with oil to create a polishing paste as well...we'll see how it goes....thanks again !!

Jeff

[astjp2]

Re: Fuel valve woes continue

If you dont want original, I can give you the part number for one that has teflon seals, its the one I am using for my STC...Tim

[mulwyk]

Re: Fuel valve woes continue

I'd like to see that valve part number, Tim. Is it available online or local?

[VictorBravo]

Re: Fuel valve woes continue

Yeah, him too and me three. I would gladly ask my IA to look at a Teflon valve as a combination of a "minor alteration" and "standard generic aircraft quality parts".

I know that a strict reading of the FAR's can oppose this thinking, but that doesn't fully address the issue of my responsibility to do anything necessary to prevent fuel fumes or liquid fuel leaks in an airplane cockpit. This is one area where progress has marched on and today's valves are safer and less troublesome.

[Jeffbo1]

Re: Fuel valve woes continue

Hey guys I got it done....I lapped the valve cones and cups using jewlers powder working tord finer grits mixed in light oil....got them satin smooth...punched some new "leather" o-rings as Forrest suggested and viola....they are tightly sealing..i will install them next weekend and barring any further leakage i think i will keep the old originals in service...hopefully my bird will be airborne next weekend...if they should start sweating or leaking i will look into the teflon units Tim suggested...otherwise I am confident now I have them refreshed as good as possible...wish me luck...Jeff

[Mark Julicher]

Re: Fuel valve woes continue

Keep working that STC Tim,
A bunch of us are rooting for you!

[rodder 440]

Re: Fuel valve woes continue

I'd suggest EZ TURN FUEL LUBE, mil-g-6032 d, Type I. The stuff is great for applications like tapered valves; it makes them turn real eazy with no leaks. It's kind of sticky stuff, and fuel just won't dissolve it.

[Jeffbo1]

Re: Fuel valve woes continue

I'd suggest EZ TURN FUEL LUBE, mil-g-6032 d, Type I. The stuff is great for applications like tapered valves; it makes them turn real eazy with no leaks. It's kind of sticky stuff, and fuel just won't dissolve it.

Thanks pal, i'll get some fuel luibe in there and we should be good to go...hopefully for quite a while! thanks./..jeff

[Edwin Otha]

Re: Fuel valve woes continue

When Aviat quit using the Imperial valve they published a Service Bulletin to substitute an Apollo manufactured valve. You might be able to use it.
EO