Guys: I have developed this air bubble over the last 18 months in my -9A with dual brakes. I have completed an archive search and read the write ups of the various problems with bubbles in brake lines, both left and right.
My problem is a little different, I am getting air in the left brake system only and it is causing the co-pilot's (CP) left brake to fail completely, due to excessive bubble in crossover line in a couple of weeks time. The air bubble grows over time and it is located at the top of the line that runs from the top fitting of the left CP master cylinder to the top fitting of the pilot's left brake. Additionally, I seem to be pumping brake fluid in the firewall mounted reservoir which is evident by the red streaks running down the firewall and onto the belly. The caliper piston is not extended excessively, I used new brake pads, same story.
I have talked to technicians at Matco and they are at a loss to explain the pumping action of the fluid into the reservoir, except that the caliper piston is extending out due to brake pad wear thus filling the reservoir to over capacity. They cannot explain why the air bubble starts little and grows larger until there is no braking due to air compression.
I bleed the brakes from the bottom with a pressure bleeder and catch the excess from the reservoir into a catch bottle with the overflow line submerged in brake fluid. Both the right and left braking system are serviced the same manner, right system has no bubbles. I have replaced the plastic lines running from the CP side to P side with flexible braided lines, no change. I can not find any evidence of fluid leaks. After servicing, I remove brake fluid from the reservoir down to about half capacity, but after a couple of weeks of use, the reservoir is full and starts overflowing. Anyone have any ideas? Dan from Reno
My problem is a little different, I am getting air in the left brake system only and it is causing the co-pilot's (CP) left brake to fail completely, due to excessive bubble in crossover line in a couple of weeks time. The air bubble grows over time and it is located at the top of the line that runs from the top fitting of the left CP master cylinder to the top fitting of the pilot's left brake. Additionally, I seem to be pumping brake fluid in the firewall mounted reservoir which is evident by the red streaks running down the firewall and onto the belly. The caliper piston is not extended excessively, I used new brake pads, same story.
I have talked to technicians at Matco and they are at a loss to explain the pumping action of the fluid into the reservoir, except that the caliper piston is extending out due to brake pad wear thus filling the reservoir to over capacity. They cannot explain why the air bubble starts little and grows larger until there is no braking due to air compression.
I bleed the brakes from the bottom with a pressure bleeder and catch the excess from the reservoir into a catch bottle with the overflow line submerged in brake fluid. Both the right and left braking system are serviced the same manner, right system has no bubbles. I have replaced the plastic lines running from the CP side to P side with flexible braided lines, no change. I can not find any evidence of fluid leaks. After servicing, I remove brake fluid from the reservoir down to about half capacity, but after a couple of weeks of use, the reservoir is full and starts overflowing. Anyone have any ideas? Dan from Reno