A while back, I built my own pressure bleeder. A garden sprayer, a pressure gauge, some tubing and a quick connect.
I did though spend $70 on 2 power probe brake bleeder adapter caps. Very high quality products, probably good enough for years of daily use instead of daily use once every 3 years!
Originally I was just going to use the adapter caps with my air tank, but I found it was annoying to have to check and refill the master cylinder so I built the pressure bleeder.
This time, I opted to NOT empty the master cylinder before bleeding. My brake fluid tested ok, looked ok, brakes felt ok so I wasn't worried about having to push more through the system. I was being lazy and didn't want to deal with extracting a small amount of fluid from an awkward location. The fluid was however green so despite the ok test strip result, I was changing it anyway.
So I happily bled all 4 wheels without worrying about the master cylinder running dry. I used a waste brake fluid jar that was about a quart capacity so I didn't once check the master cylinder during the process. Each time I bled, green fluid came out to be replaced by clear fresh fluid.
At the end, I removed the adapter cap, wondering what level of fluid I would find.
To my surprise, I found the master cylinder full of green fluid. What the??!! I distinctly remembered I had bled each wheel well beyond the point that green fluid stopped. In particular, the first wheel took a long time to turn clear.
I guess that the pressure bleeder pushed the new fluid right through the fluid in the master cylinder and that it did this for each and every wheel. Added to that, the new fluid may have been heavier and gravitated to the bottom. This certainly seemed the case when capturing the bled fluid.
The fluid level really surprised me too. It was below the max line, pretty much where it was when I started. I think the bottom of the adapter itself sits at that level and doesn't allow the fluid level to go too high. That would also explain how the new fluid bypassed the old fluid in the master cylinder.
I had about 3oz of fluid left in the bleeder so I did a small drain and refill of the master cylinder. I'll probably buy some more fluid and do a few more now.
But anyway, lesson learnt on removing the existing fluid first!
I did though spend $70 on 2 power probe brake bleeder adapter caps. Very high quality products, probably good enough for years of daily use instead of daily use once every 3 years!
Originally I was just going to use the adapter caps with my air tank, but I found it was annoying to have to check and refill the master cylinder so I built the pressure bleeder.
This time, I opted to NOT empty the master cylinder before bleeding. My brake fluid tested ok, looked ok, brakes felt ok so I wasn't worried about having to push more through the system. I was being lazy and didn't want to deal with extracting a small amount of fluid from an awkward location. The fluid was however green so despite the ok test strip result, I was changing it anyway.
So I happily bled all 4 wheels without worrying about the master cylinder running dry. I used a waste brake fluid jar that was about a quart capacity so I didn't once check the master cylinder during the process. Each time I bled, green fluid came out to be replaced by clear fresh fluid.
At the end, I removed the adapter cap, wondering what level of fluid I would find.
To my surprise, I found the master cylinder full of green fluid. What the??!! I distinctly remembered I had bled each wheel well beyond the point that green fluid stopped. In particular, the first wheel took a long time to turn clear.
I guess that the pressure bleeder pushed the new fluid right through the fluid in the master cylinder and that it did this for each and every wheel. Added to that, the new fluid may have been heavier and gravitated to the bottom. This certainly seemed the case when capturing the bled fluid.
The fluid level really surprised me too. It was below the max line, pretty much where it was when I started. I think the bottom of the adapter itself sits at that level and doesn't allow the fluid level to go too high. That would also explain how the new fluid bypassed the old fluid in the master cylinder.
I had about 3oz of fluid left in the bleeder so I did a small drain and refill of the master cylinder. I'll probably buy some more fluid and do a few more now.
But anyway, lesson learnt on removing the existing fluid first!
