About a month ago I rebuilt my hydroboost because the seals were starting to leak. I replaced the master brake cylinder when I did the rebuild since I had it off. Now I cannot seem to get the brakes to work right. I bench bled the master cylinder so I know its good. Checked all the lines and no leaks. Would the hydroboost in any way make my brakes get air in the lines or did I just not get all the air out of my line?

 

hydro is a seperate system if you have spongy brakes you have air. if you have low pedal your rears (if drum) need adjusting

 

Park the truck on it's nose (jack the back of the truck up till the front bumper is on the ground...or best you can do).
Then bleed.