The International Cessna 170 Association

My 1955 170B fuel selector has just started leaking.
It is the correct machined aluminum block version.
All B nuts are snug. I cannot tell where the leak is coming from,
the top plate and sides appear dry, no blue stains.
I get 1 drip on the bottom about every 15 seconds, but only when the RIGHT tank is selected!
It does not drip when the selector is in the OFF, LEFT or BOTH position!
Crazy. Any explanations, theories or guidance?
Thanks!

No blue stains with a drip like that? Are you using 100LL? Auto gas doesn't leave a stain.

Rebuilding that valve is trivial. Orings and a flat gasket. Easily rebuilt on the bench, in a half hour, while drinking a cup of coffee.

Removal and replacement? Easy, if there was better access. But they didn't put it where there is easy access.

You will need to drain all the fuel. Then it's really just a simple matter of undoing a few A/N fittings and a couple bolts. Fittings and bolts that are in a most inconvenient place. Hard to reach, hard to see. If your arm is in the access hole you can no longer see. Not much room to swing a wrench big enough for the A/N fittings. You need a helper to get the bolts out. Your arms aren't long enough to hold both wrenches. Prepare for scrapes and bruises on your forearms. Choose a helper that is not offended by foul language.

Pete

If you’d like to see a few pics of the accessibility of that valve you might be interested in some I posted in this post: viewtopic.php?f=24&t=177&p=72283&hilit= ... hem#p72283

Thanks for the help and that great previous thread.
I use only 100LL.
The big mystery to me is why it only leaks when RIGHT is selected..

Look at the nutplate idea at the end of that thread. replacing the 2 nuts with the nutplate enables you to service it from one side, alone. Lots easier for you to put back together and helps the guy who has to fix it in 30 years.

Great idea, the nutplates.
McFarlane has rebuild kits available: https://www.mcfarlaneaviation.com/produ ... FSO-KT-17/

Why it leaks on the right but no other place makes no sense but may become apparent when you rebuild. Perhaps it is seeping out the stem from unequal pressure of the ball spring from only the right side. All other positions will have no spring pressure from the right side or equal pressure from each side.

Yes, might be the stem, so hard to tell where exactly, hope to find out...