Bleeding brakes

Well, thanks to the knowledge on , I was lead to a very comprehensive 19 page write up (with pictures) on swapping brake boosters and master cylinders. Now, I need to learn about bleeding the brakes.

I saw brakes being bled once at a campground, but all I really remember was that there was a Mountain Dew bottle full of brake fluid and a long rubber hose.

What steps do I need to take to bleed my brakes from the point that I have replaced the booster and MC, and filled the MC with fluid...

Thanks!

Before installing MC, "bench bleed" the MC. To do that, take two small sections of brake tubing (with flare nuts and flared ends) and screw them into the MC ports. Have the tubing bent around so the end of the tubes aims back into the MC reservoir opening.

Mount the MC in a bench vise (or clamp upright securely in some manner to a solid surface), and fill reservoir with brake fluid. Pump end of MC repeatedly until lines returning to reservoir are free of air bubbles.

Now mount MC on vehicle, and connect the appropriate hard lines to the ports on the MC. Keep the MC FULL OF FLUID after bench bleeding and while mounting/connecting.

The next step is to "gravity bleed" the system. To do this, connect a piece of tubing (clear fishtank air tubing works well) to all four bleeder screws, and put the end of the tube into a suitable receptacle to catch the old brake fluid. Plastic soft drink bottles work real well. Loosen all the bleeder fittings about 1-2 turns to allow old brake fluid to run down the clear tubing, and be SURE keep the MC reservoir full. (If it runs dry, you have to START ALL OVER.)

After about 15-20 minutes (or when the fluid coming out all the hoses is CLEAR, like new brake fluid), close all four bleeder fittings.

Now it's time to "pressure bleed" the system. You will need a helper for this, someone who can pump the brake pedal as necessary. The pressure bleeding must be done on each wheel individually, in the following SPECIFIC ORDER: R. Rear, L. rear, R. front, L. front.

At each wheel, here is what is done:
1. top off the MC reservoir
2. have assistant place foot on brake pedal
3. loosen bleeder screw (while clear tube is still attached)
4. have assistant press brake pedal. It will go all the way to the floor, forcing old brake fluid out bleeder screw and thru tubing.
5. once pedal is down fully, snug bleeder screw (this is important)
6. have assistant release brake pedal to full up position
7. repeat steps 3 thru 6 as necessary until NO air bubbles are visible in clear tubing.
8. be sure to periodically check MC reservoir, and DO NOT let it run out of brake fluid. If it goes dry, you start ALL OVER.

Repeat this at all four wheels. When done, tighten all bleeder screws, remove bleeder tubing, top off MC reservoir, and replace cap on reservoir.

Note: brake fluid will harm most painted surfaces. Be sure to wash any spilled brake fluid off with water.

Wow so helpful, I would have just told him to search for previous posts. Anyway, the bleeding of brakes can be greatly expidited by the use of a vaccuum bleeder pump (hand operated). If you can find a good one cheaply ($20) and have any other vehicles to work on I would get one.

Jeff-

Excellent help. Thanks. Now I am ready to go. Appreciate it!

bajacalal said:

Wow so helpful, I would have just told him to search for previous posts. Anyway, the bleeding of brakes can be greatly expidited by the use of a vaccuum bleeder pump (hand operated). If you can find a good one cheaply ($20) and have any other vehicles to work on I would get one.

Click to expand...

Yep, I just did this on my car after replacing the front calipers. I used the hand vacuum pump/gauge kit from AutoZone. It's useful for checking vacuum, testing vacuum switches, and bleeding brakes.

Another handy option is to replace all 4 bleeder screws with speed bleeders, these are spring loaded bleeders that you loosen a bit and use the same way as a normal bleeder, push the brake pedal and the speed bleeder releases, let the pedal go and the bleeder closes. Advantage is you don't have to stay under there and it turns it into a one man job. Yea, you leave them in there, when done tighten them backup like normal bleeders. About $5 a set or so.
The other option if you are really going to be taking care of your brakes all the time is to get a pump up pressure bleeder that you add fluid to a tank, put adapter on master cylinder, pump up tank to pressurize it then bleed. About $50 for the kit.

Speed bleeders are the most handy things they ever made.I have them on my xj,and my harley.

open 1/4 turn,pump the brake untill only fluid comes out,close it.You can bleed brakes totally by your self.