No brake pedal pressure??

Broncstang · Sep 18, 2006

4 wheel power Discs, Ford Front & GM Rear

BTW: The brakes worked fine before I took them apart.

I just replaced the rear GM calipers, and front outer brake lines on my Bronco and was attempting to bleed my brakes but couldn't build much of any pressure to the pedal. With all the caliper bleed screws closed I pump the brake pedal repeatedly and only eventually build a little pressure at the bottom of the pedal throw. I used this pressure to attempt to individually bleed the air from the calipers but it never built any more pressure at the pedal. I'm assuming the master cylinder is bad but it worked fine before I swapped the parts.

Any Ideas???

The master cylinder has plenty of brake fluid in the resivors, and I don't see any leaks at the fittings.

broncnaz · Sep 18, 2006

Might just need to bleed the MC first did all the fluid leak out while changing parts? You can try leaving the bleeder screws open until fluid starts coming out. If you still dont get a pedal then it may be the MC it could have gotten some rust/dirt under the seals and wont build pressure anymore.

Apogee · Sep 19, 2006

My guess is that you drained a lot of fluid out of the system by swapping the front lines and rear calipers at the same time so that the MC won't generate pressure in the front or the rear system. I just changed some lines and it took a while to bleed the air out of the system before there was much of any pressure at the pedal. I'll second the gravity bleed suggestion.

Gummi Bear · Sep 19, 2006

Projects like this are why the sell brake fluid by the quart. ;D

Keep bleeding, like the others suggested.

I built a catch bottle out of a 1 litre soda bottle, drilled a hole in the lid for a piece of vinyl tubing that fits snugly over the bleeder nipple (and glued it in place), and a 1/16" relief hole in the cap for expansion. It makes bleeding brakes so much easier it's not even funny. It also allows you to monitor the air coming out of the bleeders. I've got ~$3 in the tubing and the cost of the soda.

Past_Miner · Sep 19, 2006

I bought the smallest, cheapest weed sprayer Wal Mart could supply. I put $1 worth of clear tubing on it with a little ball valve in the line. I am always trying to bleed brakes by myself so now I do it backwards, from the caliper to the master. It takes very little pressure and it is usually easier to push the air bubble up hill than it is downhill.

Oh, one more thing. I have to keep a turkey baster around to remove fluid from the master occasionally. Don't use too much presure either, it will shoot all over your hood if you are not careful.

Broncstang · Sep 19, 2006

I replaced the master cylinder today and nothing changed, well except for a nicer looking engine bay...

I resumed bleeding the brakes again and while the pedal still goes to the floor, it is getting better so I'm agreement with your suggestions that there's just air in the lines still.

When you bleed the brakes backwards from the caliper, are you connecting a pressurized line (like your weed sprayer)to the bleeder screw? I've never done it this way before...

Gummi Bear · Sep 19, 2006

Did you bench bleed the M/C before installing it?

It makes a huge difference, if not.

Broncstang · Sep 19, 2006

Yeah, I Bench Bled the MC before installing it today.

No brake pedal pressure??

Broncstang

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broncnaz

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Apogee

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Gummi Bear

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Past_Miner

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Broncstang

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Gummi Bear

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Broncstang

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