Bleeding Brakes - Part 2

TLDR

• Collected a bunch of tools and tried again to bleed the brakes

Details

I bought a few different tools from Amazon to do the brake bleeding again. Among other things, the important parts are:

• A few fittings (1/4 NPT to 1/8 NPT female)
• Tubes of different sizes
• A $40 brake bleeding kit
• A $10 8 oz oil spout

I used the fittings to connect all the lines together. The brake bleeding kit comes with a small reservoir and was supposed to act as a pressure pump.

I pumped the brake fluid fully through the lines, then connected the fluid line to the bleeding valve. Then started pumping through the bleeding kit. It was a piece of shit. It was not able to hold pressure and leaked like crazy. I requested Amazon refund immediately.

The oil spout worked really well. It was able to very reliably pump the fluid into the airplane. I made a small mistake of buying the oil spout with a metal can. I wish I got a transparent can to see how much fluid I had in the pump.

Bleeding Process

With the oil spout setup, I connected the lines first on the pilot side, and pumped it a few times to ensure there is a positive pressure in the tube, and no leaks. Then I closed the parking brake and opened the bleeder valve on the passenger side and pumped away.

As I continued to pump, the fluid came out from the passenger side. I kept pumping until the fluid coming out of the passenger side was a continuous stream. Then I turned off the passenger side valve while continued to pump the oil spout to maintain positive pressure. At last I turned off the pilot side valve.

Next I opened the parking brake, and connected the bleeding lines to the passenger side and pumped the fluid to the front until it came out of the reservoir. As the reservoir filled up I just used a syringe to transfer it back to the oil spout.

While doing all of these, I kept pushing the brake level to help the fluid move and, hopefully, push the air bubbles out.

I kept doing this for 20-30 minutes or so but the brake was still soft. I switched sides and pumped from pilot side for a full oil can worth of brake fluid. It didn’t really help.

Then I decided to try moving the lines and throttle quadrant at different positions to help the air flow out. I tried to put the quadrant sideways, and flip it upside down entirely. And also tilted the airplane tail to almost touch the ground. And I knocked all the tubes and cylinders to help air move.

After a few more oil can worth of pumps, the brake felt more firm. I then closed the parking brake again, and redid the left-right valve cross bleed a few more times.

The brake now feels reasonably firm. And when I close the parking brake, I cannot move airplane. The wheels are locked (at least for my muscle push).