DoubleOught wrote:Having similar problems, can’t push fluid up from bottom, even after I removed and cleaned bottom bleeder. Going to get a new oil can pump tomorrow, mine is about 10 years old it might be weak. Just in case wear did y’all find master cylinder rebuild parts / kits ???
You can get the piston o-ring and lock o seal parts from Aircraft Spruce.
I did eventually get my brake to work. We bled it from the bottom up again with no real improvement so I replaced the piston o-ring again since I had ordered a few and that worked. I’m still not sure what exactly was the issue.
You’ll want to also pick up some of the small cotter pins for the ends of the shaft that goes through the piston rod clevis. I had some on hand so I didn’t order any. The part number is in the IPC.
If you remove the cover and piston while leaving the master cylinder in place you can fill from the bottom, and any air should bubble right out. Fill the cylinder to within about 1/4” to 3/8” of the top, then install the overhauled piston and cover assembly, and you won’t even have to bleed.
Miles
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
Does the bottom bleeder have a check valve in the fitting itself ??? For some reason I can’t push fluid through it either way.
There are old pilots & There are bold pilots, But there are no old bold pilots !!!
2010 Team Tandem Airbike N700XX
1953 Cessna 170-B N3401C
First plane Cessna 175A N7000E
It sounds like you do not have that lock out seal correctly gapped [40thou]. I pull my brake cylinders and brake pucks apart every 5 years for a clean out. The oil breaks down with water and heat contamination. The bores of the brake pucks are often corroded. One of my brake pucks was very badly corroded and new not available . So a friend who has a engineering approval machined out the bores and pressed in some stainless sleeves. Totally great. I,wasn’t thinking and should have had both done . Plus the seals are so cheap.
Yes you can buy bleeder screws with one way check valves. Like to help but we need a bit more info to be effective. If you need a pump there’s two examples on page 1 of this thread. Guess which one a Canadian might own
DoubleOught wrote:Does the bottom bleeder have a check valve in the fitting itself ??? For some reason I can’t push fluid through it either way.
I assume you are talking the bleeder in the wheel cylinder. No, there is no check valve at that location other than dirt. You do have to open the bleeder far enough for it to open. Try another quarter turn from what you where doing on that bleeder Also it you happened to have a parking break, original or otherwise, installed and on, you will not be able to bleed the brakes cause the parking brake is holding the one way valve closed.
The only check valve in the system is in the master cylinder at the lock-o-seal. See my drawings below.
At rest the Lock-o-Seal between the piston rod and the piston should have a .040 gap. Fluid can flow past the piston in either direction around the piston shaft.
Under pressure the piston shaft closes the gap and it is sealed by the Lock-O-Seal, before it starts pushing the piston and pressure forward of the piston is built.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
dstates, has your Brake Master Cylinder issue been completely resolved?
I hope you have had success.
It is such a good feeling to stand beside aircraft and push top of brake pedal while a friend is trying to rotate the wheel. Clamping action - repeatly tested. Know before you go.
Enjoy your C170 - a privilege - Freedom to fly in the USA - Blue Sky
MoonlightVFR wrote:dstates, has your Brake Master Cylinder issue been completely resolved?
I hope you have had success.
It is such a good feeling to stand beside aircraft and push top of brake pedal while a friend is trying to rotate the wheel. Clamping action - repeatly tested. Know before you go.
Enjoy your C170 - a privilege - Freedom to fly in the USA - Blue Sky
Yes, it is working good now. Did some taxi testing yesterday and worked great! I’m glad that is done.
The Big Dummy (me) finally figured it out, the bleeder is two pieces, I was trying to bleed them by loosing the sleeve and not the actual bleeder. Once the light came on I was able to get both sides with good brakes and good petals in less than 20 minutes. Of course I took everything apart and cleaned it completely last night. Thanks for all your help
There are old pilots & There are bold pilots, But there are no old bold pilots !!!
2010 Team Tandem Airbike N700XX
1953 Cessna 170-B N3401C
First plane Cessna 175A N7000E
