Mr Charles
Well Known Member
I have a 4 with a cleveland 10-30 master cyl. that seems to be bypassing. It will not pump up at all. I see a rebuild kit in vans and assume this is what I need. Any tips on rebuilding and bleeding?
Van's Air Force
Don't miss anything! Register now for full access to the definitive RV support community.
Master cyl rebuild
- Thread starter Mr Charles
- Start date
Buying the individual MS O-rings cost less than the kit.
If you have leaks, be sure to INSPECT all the parts closely. I have seen aluminum rubbing the steel piston rod leave a build up making the unit hard to seal thus it leaks in short order. If you are getting leaks, also check to make sure that the master cylinders are not mounted in a bind causing side loads and leaks.
Mr Charles
Well Known Member
master cyl rebuild
Thanks all for the replies.
The cylinder is NOT leaking...out anyway. After 3 weeks non-flying, I got in and the "pedal went to the floor." I inspected whole system for leaks, then with an IA friend, we pumped fluid through bleeder with a "modified oil can" quasi pressure bleed. Pumped, pumped and pumped, refilled "oil can," and repeated 5-6 times. Tried gravity bleeding, pump/hold and crack, and fed from the bleeder until we had run 1/2 gallon (it seems) of fluid back out the reservoir. Still no pedal firmness or ability to pump up. But no leaks...is it possible for the master to internally bypass, hence no pressure, yet not leak? Is this common? Will new O'rings fix this?
Thanks for your time.
Charles
Thanks all for the replies.
The cylinder is NOT leaking...out anyway. After 3 weeks non-flying, I got in and the "pedal went to the floor." I inspected whole system for leaks, then with an IA friend, we pumped fluid through bleeder with a "modified oil can" quasi pressure bleed. Pumped, pumped and pumped, refilled "oil can," and repeated 5-6 times. Tried gravity bleeding, pump/hold and crack, and fed from the bleeder until we had run 1/2 gallon (it seems) of fluid back out the reservoir. Still no pedal firmness or ability to pump up. But no leaks...is it possible for the master to internally bypass, hence no pressure, yet not leak? Is this common? Will new O'rings fix this?
Thanks for your time.
Charles
Upside down!
Gents,
You cannot bleed master cylinders if they are upside down (RV4). If your rod and spring is pointing down, take the cylinder off the rudder pedal, turn it right side up and bleed them. Should only take 5 minutes. Also, have you checked your puck O rings in calipers - easy to replace if they are leaking. Good luck!
Gents,
You cannot bleed master cylinders if they are upside down (RV4). If your rod and spring is pointing down, take the cylinder off the rudder pedal, turn it right side up and bleed them. Should only take 5 minutes. Also, have you checked your puck O rings in calipers - easy to replace if they are leaking. Good luck!
Better yet
Flip them over. They work better mounted with the rod up and they will fit l that way in the -4. You will thank yourself everytime you have to bleed the brakes.
Flip them over. They work better mounted with the rod up and they will fit l that way in the -4. You will thank yourself everytime you have to bleed the brakes.
Not true...I had upside down master cylinders on my RV-4 for 20 years and was able to bleed them many times...albeit not easily...
With the original Cleveland master cylinders I had no choice but to mount them upside down because that's the only way they would fit (and that's how the plans showed them).
Last year I had leakage problems, so decided to switch them out for Matco's (which I bought from Van's) They are thinner and allow the cylinder to mounted in the traditional 'right side up' direction. I do like it better this way...and yes, they are definitely easier to bleed!
Tom
San Antonio
RV-4 flying for 21+ years
RV-7A under construction
rvpilot
Well Known Member
Welll.....
Took 'em out, turned 'em over, and bled the system again. Got brakes!!
I may look at mounting them right side up later, but for now I'll leave 'em like they are. It may have been possible to bleed them upside down, but it wasn't that much trouble to turn 'em over, and it sure made bleeding much easier.
Thanks for the tip Hempy.4!
Mr Charles, you should give this a try before you go to the trouble to rebuild the cylinders.
Took 'em out, turned 'em over, and bled the system again. Got brakes!!
I may look at mounting them right side up later, but for now I'll leave 'em like they are. It may have been possible to bleed them upside down, but it wasn't that much trouble to turn 'em over, and it sure made bleeding much easier.
Thanks for the tip Hempy.4!
Mr Charles, you should give this a try before you go to the trouble to rebuild the cylinders.
