Bleeding Brakes Again...

[Michael Burbidge]

During my inspection the inspector noted that there was an air bubble in my brake line. So I'm bleeding them again.

I'm using the push up from the bottom method. I have dual brakes. It works great until it gets to the passenger side master cylinders. On both the right and left pedal there is about a 1 inch air bubble that I can't push through the master brake cylinder.

Fluid is still coming out the reservoir, so I know that brake fluid is going through the entire line.

Did anyone else struggle with this?

Thanks,
Michael-

[lr172]

I am still a month away from bleeding my brakes, but have wondered about getting bubbles stuck at the high point in the lines between P and C/P mater cylinders. You will need to get the fluid moving quickly to get the bubble out. You can also pull the C/P master cylinder and hold it level or higher than the bubble to work it out. The air bubble is lighter and wants to rise, if given time.

The key is to keep the volume of flow up until it is gone. Whenever the flow stops, the bubble will start rising. You can also pull the line off the resevoir and put it in a can. Then just keep pumping fluid, without stopping, until the bubble is gone. If you have to stop to keep emptying the tiny resevoir, you will struggle to clear the bubble.

Larry

[N427EF]

The bubble you see in that line is simply a transfer line not a pressure line.
Check your brakes and if they are solid you don't need to bleed them again.
I saw bubble in my RV-8 for all the years I had owned it and the brakes were solid.
On my 10 I have a braided stainless steel hose so I can't see the bubbles.

[9GT]

I just helped my buddy rebuild a leaking caliper (Matco 3 pucks) on his Cozy MKIV and reline the brake pads. We used a pressure pot hooked up to the caliper's but still had spongy brakes. We ended up removing the caliper and re-bled the system holding and manipulating the caliper as they were pressurized and bleeding. He has clear lines and we could see the bubbles move out of the calipers as we moved them around. We still had trapped bubbles in the lines at the parking brake valve and had to un-mount that and manipulate it to get the bubbles moving again. Brakes were firm after that. I had no such problems on my -10 stock brake system.

[lr172]

Originally Posted by N427EF

The bubble you see in that line is simply a transfer line not a pressure line.
Check your brakes and if they are solid you don't need to bleed them again.
I saw bubble in my RV-8 for all the years I had owned it and the brakes were solid.
On my 10 I have a braided stainless steel hose so I can't see the bubbles.

We need to be sure which line has the bubble. My RV-6 has clear pressure lines between the pilot and co-pilot master cylinder lines. Bubbles there are a problem when brakes are applied by the co-pilot, but not the pilot.

Larry