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  1. #1

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    Can't fix a leaking retract valve

    I have three different Robart retract air valves and they ALL leak! It seems that the o-rings have shrunk or something. I also have a Byron valve with the same symptoms. What's the trick for keeping air in my retract system? Any tips? Can I get the o-rings locally at a hardware store maybe?

  2. #2

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    RE: Can't fix a leaking retract valve

    I dont know it would help old O-rings but DC 55 Molykote o ring grease is designed to slightly swell o rings DC stands for Dow Corning.

  3. #3

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    RE: Can't fix a leaking retract valve

    Try some 10 or 20 weight silicone shock oil for RC cars from your LHS. Works great to lube the O rings and keep the seal. Use some in all my retract systems. A couple of drops when I pump air in the first flight and the last flight of the season keeps all the O rings in the retract system plyable and sealing...

  4. #4
    invertmast's Avatar
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    RE: Can't fix a leaking retract valve

    are you sure its the valve and not blow by from one of the landing gear cylinders?
    Thomas W.
    Euro-sport Evo, Scratch built 1/7 F-14D Tomcat, 26.5% Gee Bee R2

  5. #5

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    RE: Can't fix a leaking retract valve

    If its coming out of the valve its most likely blowing past the air cylinder.
    Check the air cylinder.
    I had the same problem and it took me some time to work out it was the air cylinder.
    The reason it looks like the valve is the retract works by exhausting the redundant air out of the valve but if there is a leak in the cylinder it will do this continually.
    You can check by squeezing off the exhaust side after the retract is either up or down.
    If the air stops when it is squeezed then its coming past the o rings in the cylinder.
    Dave.

  6. #6

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    RE: Can't fix a leaking retract valve

    Sorry didn't see other post after Invertmast Right On


    Hi,

    What Invertmast just posted about agear cylinders leaking could be your problem, I have replaced and rebuilt a air valve for the same problem, one way to test pull the air line side thats "suppose to not have air on it and run a short length of hose in a small cup of water - bubbles - leaking "O" ring in cylinder.

    Charlie Evans

    KickIn Chicken
    Team Hodges
    Leesburg,Georgia

  7. #7

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    RE: Can't fix a leaking retract valve



    What chicken said + the dc 55

    Cheers Bob T

  8. #8

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    RE: Can't fix a leaking retract valve

    Use air tool oil. It is generally compatable with the o rings...

  9. #9
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    RE: Can't fix a leaking retract valve

    I had the same problem, bought a silicone spray can on a gas station. Sprayed in a LOT of silicone spray into the system via the filler valve.

    Now it keeps the air for 14 days.

    It works, its cheap, and you get a can within minutes....

  10. #10

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    RE: Can't fix a leaking retract valve

    I took everyone's advice and I think nearly all of the o-rings are leaking everywhere. These are 30 year old Byron retracts. What are my options here? It looks like I'll be on the hunt for o-rings. Thanks for the replies folks!

  11. #11
    Live Wire's Avatar
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    RE: Can't fix a leaking retract valve

    You can get O rings at an auto parts store or tractor shop. I used Norvey, INC. Turbine oil I picked up at ACE Hardware, worked on Robart valve. It take a while for it to work.
    Larry K
    Sig Brotherhood # 1 Sig Kadet Brotherhood # 4 WACO Brotherhood #34 Cub Brotherhood 14

  12. #12

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    RE: Can't fix a leaking retract valve


    ORIGINAL: flyingvranch

    I took everyone's advice and I think nearly all of the o-rings are leaking everywhere. These are 30 year old Byron retracts. What are my options here? It looks like I'll be on the hunt for o-rings. Thanks for the replies folks!
    Your BEST option is to have Down&Locked convert them to electric and never worry about a leak again. Instead of carrying an aircompressor to the field all the time, you just charge another battery, which your charging batteries anyway, so whats the big deal. Theres nothing worse than air retracts that dont work at the worst possible time, just before landing.
    KEEP UM FLYIN

  13. #13

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    RE: Can't fix a leaking retract valve

    the problem with Down and Locked is the PRICE. If you had that conversion done what did it cost you??
    The only good planes are in the air having fun

  14. #14
    invertmast's Avatar
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    RE: Can't fix a leaking retract valve


    ORIGINAL: STUKA BARRY


    ORIGINAL: flyingvranch

    I took everyone's advice and I think nearly all of the o-rings are leaking everywhere. These are 30 year old Byron retracts. What are my options here? It looks like I'll be on the hunt for o-rings. Thanks for the replies folks!
    Your BEST option is to have Down&Locked convert them to electric and never worry about a leak again. Instead of carrying an aircompressor to the field all the time, you just charge another battery, which your charging batteries anyway, so whats the big deal. Theres nothing worse than air retracts that dont work at the worst possible time, just before landing.

    Thats not the best option, its the most expensive one. I have seen more electric retracts fail than any properly setup pneumatic gear!

    The key to pneumatic gear is... If it wont hold air for a significant amount of time (no more than a 5 psi drop in no less than 3 hours, IMO) then you need to find the leak and fix the problem!
    Thomas W.
    Euro-sport Evo, Scratch built 1/7 F-14D Tomcat, 26.5% Gee Bee R2

  15. #15

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    RE: Can't fix a leaking retract valve

    flyingvranch
    first step is to find the leak. There are five barbs on your valves. Hook the center barb to a air pump (hand air pump). Run a peace of tubing between the two retract barbs and then between the two deployed barbs. Now submerge the valve and add pressure, look for leaks. You should also pressurize all sides of the cylinders and watch for air loss. You can do this by attaching the line coming off the cylinder to the air pump. If it leaks cut the line at the cylinder, slide new hose over the nipple and test again. If it leaked with the old hose and not with the new, the old hose is bad, if it leaks both ways the cylinder o-rings are bad.


    New o-rings can be bought at McMaster Carr.


    Joe
    If it doesn't fly it wount cetch my eye.

  16. #16

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    RE: Can't fix a leaking retract valve

    I had the same problem, after several new valves and replacing the o rings found out it was the retract. The retract was not fully closing all the way because of a gear door spring. Moved the position of the spring, thus allowing it to fully retract and it has worked flawlessly ever since!


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