I was rebuilding a rear caliper and stupidly had the other rear caliper swung up because I was also replacing the pads and rotors. I started bleeding the one rear caliper and the brake bluid came out the other rear caliper during the process running my master cylinder dry, I'm so stupid! haha.

Anyway, my question is how do I bleed the master cylinder. I would REALLY like to do it without taking the MC out of the car. After bleeding all four brakes the brakes still feel really soft and don't allow the car to stop quickly. I'm pretty sure it's the master cylinder that needs to be bled, right? Could I just bleed the brakes again and fix it? If I do need to bleed the master cylinder, how do I do it? I can't find a write up or anything other than "cracking the lines" at the master cylinder and pressing down the brake pedal just like bleeding the brakes.

How do I "crack the lines?" Can anyone help me out with the process? Thanks a ton!

 

have you ever bleed brakes? If so it's the same procedure. but first find out why you system ran dry, A leak maybe?. Them have a friend assist you with pumping the clutch pedal then on the slave cylinder there is a bleeder screw (10mm) open until air hisses its way out. depending on how dry it ran it may take up to several times before you have pressure again

 

He is referring to his brake master cylinder,not the clutch m/c...

 

Here is the master cylinder bleeding procedure per fsm..It's the same procedure as bench bleeding,but on the car..

 

might be worth it to get speed bleeders

 

i guess i should of had read it first

 

Great! So basically, I just disconnect the metal fluid lines going into the master cylinder and then plug them with my fingers while someone pushes in and lets out on the brake pedal slowly a few times? Will the air bubbles just bubble up right out of the resevoir? Then do I just recconect those metal fluid lines? Couldn't air get in again when I reconnect them and have to take my fingers off?

Thanks a ton for the help!

 

As long as do not press the brake pedal,no air will introduced into the master cylinder even when you're fingers are no longer over the holes

You will still have to bleed the air out at each wheel after hooking the lines back up though...

If you are not "exactly" sure how to correctly bleed a brake system of air,here is a little writeup..



1. Loosen the lug nuts of the road wheels and place the entire vehicle on jackstands. Be sure that the car is firmly supported before going ANY further with this procedure...

2. Remove wheels..

3. Install one lug nut backward at each corner and tighten the nut against the rotor surface. Note that this step is to limit caliper flex that may distort pedal feel.

4. Open the hood and check the level of the brake fluid reservoir. Add fluid as necessary to ensure that the level is at the MAX marking of the reservoir. Do not let the reservoir become empty at any time during the bleeding process.

Bleeding Process
1. Begin at the corner furthest from the driver and proceed in order toward the driver. (Right rear, left rear, right front, left front.) While the actual sequence is not critical to the bleed performance it is easy to remember the sequence as the farthest to the closest. This will also allow the system to be bled in such a way as to minimize the amount of potential cross-contamination between the new and old fluid.

2. Locate the bleeder screw at the rear of the caliper body (or drum brake wheel cylinder.) Remove the rubber cap from the bleeder screw..

3. Place the box-end wrench over the bleeder screw. An offset wrench works best – since it allows the most room for movement.

4. Place one end of the clear plastic hose over the nipple of the bleeder screw.

5. Place the other end of the hose into the disposable bottle.

6. Place the bottle for waste fluid on top of the caliper body or drum assembly. Hold the bottle with one hand and grasp the wrench with the other hand.

7. Instruct the assistant to "apply." The assistant should pump the brake pedal three times, hold the pedal down firmly, and respond with "applied." Instruct the assistant not to release the brakes until told to do so.

8. Loosen the bleeder screw with a brief ¼ turn to release fluid into the waste line. The screw only needs to be open for one second or less. (The brake pedal will "fall" to the floor as the bleeder screw is opened. Instruct the assistant in advance not to release the brakes until instructed to do so.)

9. Close the bleeder screw by tightening it gently. Note that one does not need to pull on the wrench with ridiculous force. Usually just a quick tug will do.

10. Instruct the assistant to "release" the brakes. Note: do NOT release the brake pedal while the bleeder screw is open, as this will suck air back into the system..

11. The assistant should respond with "released."

12. Inspect the fluid within the waste line for air bubbles.

13. Continue the bleeding process (steps 11 through 16) until air bubbles are no longer present. Be sure to check the brake fluid level in the reservoir after bleeding each wheel! Add fluid as necessary to keep the level at the MAX marking. (Typically, one repeats this process 5-10 times per wheel when doing a ‘standard' bleed.)

14. Move systematically toward the driver – right rear, left rear, right front, left front - repeating the bleeding process at each corner. Be sure to keep a watchful eye on the brake fluid reservior, Keep it full..

 

i assume you also have some flared wrenches for the lines?

 

Yes, I have a crescent wrench which has worked fine for bleeding the brakes. Thanks for all the help everyone!

 

crescent != flared