Well, I've just wasted about 4Hrs trying to put in a new master cyl and bleed the brakes. I have tried everythng. It's either help from here or off to the Brakes @!$us shop in the morning.

Followed FSM for sequencing and yes I included the proportioning valve. I bench bled the master properly I think. I'm using a vacuum tool to bleed each wheel. I am mostly getting air and hardly any brake fluid. I've tried bleeding at each wheel 4times. I have kept the reservior full at all times.
Thanks in advance.
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put a finger full of grease around the bleeder screw.
keeps it from sucking air.

Thanks for the tip! I didn't do the bench bleed properly either (I read up on the procedure.) I may never get the air out unless I remove master and start all over again. Hmmmmmm.

you probably dont need to compleetly remove the master just the lines and follow the bench bleading process with it mounted, of course its only 2 bolts to take it compleetly off at that point.

Have you ever looked at the MC when it is mounted on the booster? They are at an angle with the front pointed up. It will trap air there with no place to go. You can jack the back of the rig up until the barrel is level then run the bench bleeding cycle on it.

true but non the less its only about a 5 min job to take the lines off and then pull the master. the bleading is the hard part

Bench bleeding a master is super simple. Go to the auto parts store and get about 2 feet or so of METRIC brake line. Find one with 2 MALE ends that match the threads on your master cylinder. Remove the master cylinder from the truck and put it in a vice, keeping it level. Cut the new brake line in half. Screw each piece into the master cylinder. Bend each piece in a loop so they are fully submerged into the resivour. Fill the master a little more than half way full of clean brake fluid. Using a screwdriver, push in the piston in short, 1" or so strokes. Keep doing it until you get a good stream of brake fluid, no bubbles. Usually takes less than 2 minutes. I've tried other ways, and this is by far the fastest and easiest way. Then bleed the rest of the brake system. Try it the old fashioned way, by hand, not using the vacuum bleeder.

I have never had any luck with a vacuum bleeder.

This is what I have used for the past fifty years, works great and only takes one person.



This is the correct bleeding procedure taken from the FSM, longest to shortest then LPSV.

Takes a little practice with the vacuum brake bleeder to get the hang of how much to open the bleeder vs. how much fluid and air you get out. I like to put on the hose over the end of the bleeder and pull a hard vacuum. Then slowly crack open the bleeder until you start to pull some fluid and maintain the vacuum. I usually just pull out one container full of fluid the first time (~4 oz.) then close the bleeder. Top off the reservoir and pull another few ounces, this time slower and with the bleeder just barely open to minimize air leaking around the threads. You can usually tell the difference in leaking air (will come in via fine bubbles) vs. trapped air in the brake like (it will come in in big bubbles, sort of like turning a bottle upside down and having the liquid inside pour out and the air comes in in big glugs).

Sounds like you may be opening up the bleeder too far if you are getting too much air. I've never used sealant on the bleeder threads, but maybe give that a try.

Thanks for all the tips. I'll give it a go!