master cylender on 1993 GMC SUB.

[wamorris]

In changing this unit I bench bled the cylender, bled each wheel cylender. I have good brakes but if you keep pressure on the pedal it will bottom out. If you keep firm pressure on the brake pedal it goes down slowly, let off on the pressure a little and the pedal will bottom out quicker. What is my problem? Respectfully, [email protected]

[2000CAYukon]

What order did you bleed in? Should have been RR, LR, RF then LF. This is important especially after a new master is installed.

I have also found that adjusting the rear drum brakes by hand help with bleeding. It also gives a better pedal.

//2000CAYukon

[wamorris]

Originally Posted by 2000CAYukon

What order did you bleed in? Should have been RR, LR, RF then LF. This is important especially after a new master is installed.

I have also found that adjusting the rear drum brakes by hand help with bleeding. It also gives a better pedal.

//2000CAYukon

Thanks: I did not bleed in the order you stated. I will do it again but in my thinking if there was still air in the system the brakes would be spongy but would not bleed all the way down. Am I wrong in my thinking? The following sounds werid but here goes. I installed plugs in both ports and the pedal did not go down. I then installed the foward brake line, leaving the plug in the aft port. The brake pedal did not bleed down. I reinstalled the aft brake line leaving the foware plug installed. The pedal bled down in this configuration as it does when both lines are installed. Thanks for any thing you might add to this. Respectfully, [email protected]

[BlueMonster]

Check your lines. Sometimes they are full of rust and crud so detecting slight leaks in porous lines makes it a bit difficult. Take a look for slight wet spots on the lines. You might find that your line is leaking a bit and needs to be changed.

[wamorris]

Thanks for your imput, [email protected]

[2000CAYukon]

Also make sure the rubber hoses are good as well. You may have one that is expanding.

//2000CAYukon

[dramey_2004]

Hey sounds like your master cylander is bad even though it is new that don't mean it is good you have a primary cup inside of the master cylander leaking time to replace it