Matco cylinder leak

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fusionfab

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May 16, 2012
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87
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southern ontario canada
Hey everyone just looking for some insight on this. I have rerun new lines and fittings on the brakes. Filled with fluid until leaking out the "SHCS" on the top reservoir cover, bled the brakes and they are working nice and solid. However every few depressions of the pedal I'm hearing the slightest of leaks. I look and see that a very small amount is leaking between the shaft and the center collar. Picture attached. I've been looking at the diagram and there doesn't seem to be a seal at this location inside the reservoir just the outer o-ring. Would this indicate something is worn? Or too much fluid in the reservoir? It's doing this identically on both cylinders.
Any help is appreciated. Thanks
 

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Rockiedog2

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Dec 11, 2012
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Not knowing that cylinder I'm not sure about this but I think it's just overfilled. If you have normal braking and it was mine i would just fly it and watch it a while and see what happens. I believe it will likely stop leaking.
 

Vision_2012

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Apr 21, 2010
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274
Location
Shady Cove, OR
Brakes require replacement of the O-rings. They get hard and flat, allowing seepage. Even if "new", O-rings may harden due to age. I would not fly without certainty that I would not lose breaking power upon landing.
 

Dan Thomas

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Sep 17, 2008
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6,228
Those things are not designed to be filled right full. They'll overflow around the piston stem. Cessna's cylinders do the same thing. No seals around the shaft. It's worse if the filler plug isn't vented, as oil will get forced out the piston stem bushing because it extends down a ways into the fluid, and as the fluid heats in the calipers it expands and pushes up into the master. The air in the master can't get out and the oil squirts up around the stem. It makes a mess and attracts dust and forms a gooey scum.

Piper and many other had a better idea: proper hydraulic cylinders with a remote reservoir on the firewall feeding the tops of the cylinders. Seals on everything in the cylinders. No getting a kink in your neck trying to fill the masters or measuring their level. No fluid piddling out everywhere and making a sticky mess in the belly.
 

fusionfab

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Joined
May 16, 2012
Messages
87
Location
southern ontario canada
I've purchased and installed the Rebuild kits and according to diagram and instructions that came with them, just as Dan Thomas said, there isn't a seal at that stem its just metal on metal nor is it a machine fit. The majority of responses I'm getting are that I've filled them too much. I'll see how these work for the next while during taxiing and testing. Still a few months away from flying. I appreciate everyone's responses.
Thanks again
 
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