Loss of brakes.

[richards72chevy]

When I push on my brakes to get into my driveway the other day my trucked kept on going.At first this mostly happened at higher speeds but know its happening at lower speeds.I don't think its my disc rotors or pads.I don't think there is a leak master cylinder is full.Could my master cylinder be bad?Its been on there for 13 plus years.

[cdowns]

yes master cylinders go bad and need replacement at times//they are relitively cheap and available at your local autoparts store

[richards72chevy]

So one from a local parts store is acceptable?I prefer napa or o'riely over autozone.Thanks cdowns.

[richards72chevy]

I replaced the master cylinder went to bleed the brakes and no fluid was coming out of the rear passenger side when bled so I replaced that cylinder.I bled all four sides my brakes work better but they are not firm and my truck does not stop as good as it use to.What am I missing here?I bled the brakes by having some one press the pedal five times and the I opened the valve starting from the furthest wheel until clean fluid gushed out.The truck has factory power disc/drum.

[geezer#99]

Have someone pump the brakes up, and then hold pressure on the pedal, you open the bleed screw, the pedal goes to the floor, they keep it there until you have the bleed screw closed then they pump it up again and do the same process again. I do it twice on each wheel and then start over if needed.
Be sure to check the fluid level in the m/c quite often.

[richards72chevy]

Thanks geezer I think that is where I made my mistake I didn't have pedal go to the floor when I was bleeding them.

[geezer#99]

Couple more tips!!
Leave the lid on the m/c loose. Saves a mess from the geyser from pumping.
Your victim who does the pumping is totally at your command. They do only what you tell them. Otherwise you could be bleeding forever.

[sstaten69]

Yea it may take awhile to get all the air out if you didnt bench bleed the new master. I would keep bleeding it until the brake fluid coming out of the bleeder is alot cleaner looking..

[mrolds88]

You shouldn't be "pumping the brakes". Simply and slowly apply pressure to the pedal. Then open the bleeder until the pedal runs the length of travel. Close the bleeder and release the pedal, repeat as needed. When you pump the pedal you get bubbles everywhere.

[richards72chevy]

How many times should the pedal be slowly pushed down before opening the bleeder?

[Hawghauler]

When the pressure builds up, and the pedal is as firm as possible. If the pedal lifts even a little bit you can suck air in and defeat the whole exercise. I usually don't even wait for the pedal to seat on the downstroke. I let the fluid flow for a second then tighten the bleeder. Should only take a few times each wheel. I also agree you should pump out until you have clean fluid coming out first.

[Syndrome]

Originally Posted by richards72chevy

How many times should the pedal be slowly pushed down before opening the bleeder?

Only 1 time. They press the pedal(and keep full pressure on it) and you open the bleed valve. You close the bleed valve before they release any pressure on the pedal.

Once the bleed valve is tightened do it repeat the whole process. I do each wheel a few times then go back to the first wheel and start over. Also, you should make sure that your drums are adjusted correctly, or you will be bleeding them for a very long time and they still wont work perfectly.

[mrolds88]

Originally Posted by richards72chevy

How many times should the pedal be slowly pushed down before opening the bleeder?

once. When the pedal goes to the bottom of its travel, then close the bleeder and then let the pedal return. Then repeat as needed.

[geezer#99]

Only once??
What if you have no pressure?
There's no set number of times. Might be several required. JMHO!

[mrolds88]

If you have to cycle the master cylinder more than once to get pressure (whether it me moving air or fluid) you have other problems. Yes you might have to go through the bleeder/pedal cycle several times, but you should only have to push the pedal once per cycle.