More brake problems

[LiqTenEXp]

I was having an issue with the brake pedal not coming back quickly. Also sometime it would feel like I was locked out the brakes and would have to pump them and let the pedal come all the way back before I would have brakes again. Once that happened the brakes would be great till a few pushes later where I would be locked out of them again and the pedal would be slowly rising up.

I tried cleaning the MC out and got some large particles sucked out of there. I topped off the MC and went to bleed the brake booster. When the brakes were pushed all the way down, and I cracked the bleed valve, the brakes dropped to the floor. I had my assistant keep the pedal there till I tightened the bleed valve. I was using the hose on the end of the bleed valve with the other end stuck in a bucket with fluid in it method. The pedal now has NO resistance and it feels like the MC is stuck in the pedal all the way down position (aka the piston is stuck pushed all the way aft). This is bad. I can't bleed the brakes anymore if I can't pump them LOL.

Any idea? Is it time to rebuild or replace this MC?

 

[jwaller]

sounds like the hydrovac and MC needs a rebuild.

 

[JDToumanian]

Maybe a stupid question, but is the pedal return spring intact? If so,

Jon

 

[LiqTenEXp]

yes it is. When I say slow return, I am ignoring the springs tension and feeling when the pedeal mechanism actually touches the MC input shaft.

I am going with a replacement unit.

 

[jimm1009]

Also the brake pedal needs to be lubed on the pivot shaft from time to time as well.

This is more than likely not the problem as the most common problem is internal corrosion and general "nastieness" in the cylinder as the wheel cylinders sometimes have. You can isolate and prove this by removed the cotter pin and clevis pin and work the pedal independent of the master cylinder. If the pedal is very hard to move with the spring removed then you got luck and this is much easier to fix.

A rebuild kit for the master cylinder is not too bad price wise and fairly common
amongst our S.S. vendors.

Let us know that you find.

jimm1009

 

[glcaines]

I believe you have master cylinder problems. Either the fluid is leaking past the MC piston or the spring is broken. Another thought is to make sure the MC vent is not plugged up.

 

[G-Force]

Did you have air pressure in the system? It sounds like the air pack is not bleeding air off when you release the brake pedal.
I would say more an air pack problem than a master cylinder.