Bleeding brakes

[Diseazd]

I'm bleeding my brakes. The whole system is dry (no fluid in the system). I bench bled the MC and hooked up all the lines. I've been pumping on the system for an hour and still getting mostly air. Is this normal? How long does it take? Thanks. Guy

[SteveJ]

Is the fluid level going down in the master when you do this? If the system is dry, or relatively dry, I like to start with a vacuum pump. Go to the left rear cylinder and with the bleed screw open, start drawing a vacuum. Have an assistant adding fluid to the master as you do this. This way, you have someone to watch the master while you're watching the cylinder. For final bleeding, I perfer the method of having the end of the tube submerged in clean fluid and having the assistant pump the brakes. This way if the assistant lets off the pedal too soon before you can close the bleed screw, you pull fluid back into the system instead of air.

[Zforce]

What SteveJ said and start at driver rear first then pass rear pass front and so on. Speedbleeders work well too.

[Diseazd]

I'm using a vacuum pump......I keep bleeding and bleeding...some fluid...mostly air.....it just doesn't seem to pull pure fluid. I do have a fairly firm brake pedal, but still sucking mostly air from the rear passenger side. I'll keep trying.

[SteveJ]

So, the key details come out. From your description, it sounds like there is an obstruction in the line. The air you see with the vacuum pump is coming in between the hose and the bleed screw.

[Diseazd]

On all four corners?

[SteveJ]

Rust, grease, grime, dirt...yeah, that could get into all of your lines, or the two that come off the master. Another thing could be that you're not opening your bleed screws enough. Something is keeping the fluid from getting through.

[Diseazd]

How is it possible to have such a strong pedal with that much air in the system? The pedal is firm like it's air free?

[SteveJ]

While the pedal is firm, are the brakes actuated? If you have obstructions in the lines, you could just be pushing against an "immovable object". If there isn't much air in the lines between the master and the obstruction, you aren't compressing much air.

[Diseazd]

Steve......I'm thinking master cylinder. I bled the first reservoir first and the 2nd reservoir 2nd. The book said bleed both at the same time. Could this be my problem (air in the MC)? Yes the peal is activating the brakes and it is firm (doesn't get softer as I maintain pressure on the pedal). I'm thinking about pulling the MC and starting over. Guy

[Jeff G 78]

Guy, don't pull the master. I have had great luck by bleeding the MC in the car. Remove the bleeders and apply a bit of grease on the threads to seal them from leakage. With the reservoirs full and both bleeders tight, attach a tight fitting 6" long hose to one of the bleeders and insert the other end into the reservoir under the fluid level. Crack the bleeder and slowly pump the pedal up and down until there are no air bubbles circulating through the system. Tighten the valve and repeat for the other port. I have always gotten all of the air out of the MC with this method. Once done, proceed to bleed the corners as stated above.

If all else fails, buy a power bleeder for $60 and push the fluid through the system to each corner. They are a bit cumbersome to use and they waste more fluid, but they do work well.

[Diseazd]

Thanks Steve and Jeff. Just finished the job. I bled the MC again......then bled the balance valve ( under the MC by loosening the fittings on top while the pedal was depressed ). I then went to the passenger rear....this time I used a clear tube emerged in a clear cup with brake fluid in it. When the bubbles no longer were present and fluid was rising, I knew it was a success! Then to the driver rear wheel...passenger front and driver front. Those took no time at all. I hate brake work. ...........you're dealing with a liquid that eats paint. Glad that's done....thanks for the advice. Guy