Bleeding brakes, sucking air from Master cylinder?

[Jason in DLH]

I also use a Capri Tools vacuum bleeder (just to give you options).

 

[Jason in DLH]

Well...I’m fresh out of ideas for you, sorry I couldn’t help! Good luck to you! And enjoy the beers.

 

[Jason in DLH]

I just schooled myself on a master cylinder replacement...

 

[optimusprime]

Just thought of something. I did my brake change in my driveway which is on an incline. When I did the rears, my rear end was jacked up so the car was somewhat level. Now I have the front end jacked up AND it’s in an incline. Could this be causing the fluid to be emptying to the rear part of the cylinder and keeping it out of the front?


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[wjburken]

Just thought of something. I did my brake change in my driveway which is on an incline. When I did the rears, my rear end was jacked up so the car was somewhat level. Now I have the front end jacked up AND it’s in an incline. Could this be causing the fluid to be emptying to the rear part of the cylinder and keeping it out of the front?


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It's possible. Keep your fluid level up and see what that does for you.

 

[optimusprime]

The fluid level is already full. Do you think leveling the car out or raising the rear slightly may remedy this?


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[gooffeyguy]

No. Just hold them crack and pump away. The videos I’ve seen like this had it performed this way and there was no air sucked in because the hose is submerged in fluid.


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Uh, I think your technique is the problem.

Air may not get sucked in because the hose is submerged, but if there is air further up the line it will just get sucked back further.

Pump pedal and hold, open bleader for a couple seconds, close. Pump pedal and hold, open bleader for a couple seconds, close. Keep repeating until fluid has no bubbles or doesn't come out sputtering, but a nice steady stream.

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[donjetman]

No. Just a constant pump and release. The end is submerged in fluid. Worked awesome for the rear.

Do as Jason describes here in post# 28, or use a pressure or vacuum bleeder. Sometimes Also you can gravity bleed by opening the bleeder and letting it flow until 100% fluid, no air, comes out .View media item 28206

 

[wsteele]

Just because the hose end is submerged in brake fluid in the catch bottle, you can still be sucking air upstream of the submerged hose end. You can get air past the threads on the bleeder, also between the nipple and the hose.

If you are going to use the "open bleeder and pump the peddle" procedure, you need to close the bleeder valve on the caliper before taking your foot off the peddle (two person operation). That is, open the bleed screw, call to your assistant to put pressure on peddle, assistant calls when peddle stops, close valve, assistant releases pressure on peddle, check reservoir and top up, repeat.

For single person, you need to follow the alternate processes already suggested (vacuum bleeder, reverse pressure pumping fluid back up into the master where you suck it out before it overflows, etc.). These alternate processes require procedure specific tools, generally not too expensive to buy.

 

[Fless]

Be sure to NOT push the pedal to the floor when bleeding the brakes, since that can cause the master cylinder seals to leak. Put a board or something else on the floorboard under the brake pedal to stop it from bottoming out.