Hi,

Do you need to bench bleed the master cylinder if the new master cylinder is already attached to the booster?

Is bench bleeeding only required if MC is removed from the booster?

Thanks

 

detaching the master cylinder from the booster will have no affect on air in the brake system. Deataching the brake lines from the master cylinder, now thats a different story. Its generally a good idea to bleed your brake system -any- time you remove any lines. And if its a new cylinder, make sure you follow the air purge procedure that should come witht it (which basically consists of sitting there pumping the cylinder for a half hour to rid it of any stubborn air bubbles).

 

You must "bench bleed" anytime the lines are disconnected at the MC or if a new MC is installed on the car.

BUT a nice little helpful.........
Do the bench bleeding ON THE CAR. Get the little kit from NAPA/wherever. Mount the MC to the booster, but leave the brake lines off. Follow bench bleeding procedure (have a buddy do the pedal pumping) and when no more little air bubbles come out of the littles hoses, remove the bleeding kit and attach the hardlines. Now bleed entire brake system to get the air bubbles that where introduced when the hard lines came off the old MC.

 

good advise, thanks mista bone!