Vacuum Brake Bleed

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  • I'm not going to go into detail here on how to flush or bleed your brakes. If you don't know the basics of doing your own brake bleed, then I don't think your going to need any of the info I have here. But, if you are planning to do a complete brake fluid flush of your car, then this little trick should help you.
  • I bought one of those cheap Vacuum Brake Bleed kits from [Harbor Freight] with the intention of using it to vacuum all the fluid through the lines, drawing in clean fluid from the Master Cylinder.

  • I knew that 99% of the people that use them complain that the air just leaks in from around the bleeder screw threads. And I was no different. As soon as I cracked the bleeder screw, I could see and hear air seeping in past the threads. I tried a few different things in an attempt to seal the threads, but nothing worked very well.
  • Then, I got the bright idea of trying to use a piece of rubber hose around the threads to seal them off! And guess what? It worked! I used a piece of 1/4" ID clear rubber hose cut to exactly 3/8" in length.

  • The ID of this hose made for a snug, but good fit around the threads of the bleeder screw. I completely removed the bleeder screw from the Caliper, slid the piece of rubber over the threads, and up to the bolt head, then re-installed the bleeder screw. Once the screw is seated all the way back in, the clear rubber piece gets squished quite nicely between the Caliper, and the head of the bleeder screw. Making a reasonable seal. The two photos below show how it went together.

[Link to very hi-res version] [Link to very hi-res version]

  • Now, reattach the Vacuum bleeder kit and pump it up to about 10-15 in/Hg. Crack the bleeder screw about 1/4 turn, and the fluid flowed perfectly into the vacuum reservoir. Don't crack the bleeder too much though, I found that too much, and the air would once again start to seep in.
  • Once I was done, rather than remove the bleed screw, and risk getting a bit of air back in the system (I doubt it would have through), I simply cut the clear rubber hose off of the bleed screw. I had plenty of extra to make a measly 4 x 3/8" pieces to go around.
  • I had a buddy help me do the final bleed with the old method of pumping the brakes, while I cracked the bleeders. Not one of the calipers had any air bubbles in them. The seal from the piece of rubber was plenty to keep all air out of the system.
  • Voila! a Make Shift setup, that allowed me to bleed my brakes in about 30 minutes. And it worked perfectly on my clutch too!