I have a F350 7.3 nonturbo.I have to pump the brake pedal to get good firm brakes.things i have done replaced mastercycl,booster,front hoses,brakes,calbrs,I have vac to booster.bleed brakes several times.no sign of leaks.Don't know if problem is rear brakes ,can hear them working,just waiting on temps to come up outside to pull rear drums.Maybe someof yall have had trouble like this before.

 

hmmm, maybe the shoes just need to be adjusted (down and out) does the truck have abs?

 

Did you "bench-bleed" the new Master before putting it on the truck? Bleed all 4 wheels? New or Rebuilt Master?

 

did you bleed the back passenger side, then back drivers side, then front pass. side, then finally front drivers side (alway bleeding from the farthest from the master)

 

That's my guess also. The rear brake shoes are supposed to self adjust. Unfortunately they don't always work as they should. I think you will find the problem with your rear brakes as you suggested.

 

yea my self adjusts dont work, so when the brakes go a little soft, i give each side a few turns (till i can feel a little bit of resistance when i turn the wheel)

 

I had this same problem in a ranger I had and the problem was the new wheel bearings I had installed were working their way loose. I bleeded the brakes and the problem still persisted..check your bearings.

 

Thanks i bleed the brakes right.I ran a qrt of brake fluid through the system till i got new at all 4 brakes.I did bench bleed the master first.Hopefully it will get a little warmer (around 40 haha)this week so i can tear into it full force.anymore input sender my way.

 

If you have abs there is also a bleeder on the abs modual it is up inside the driver side frame rail behind the front axle

 

my brakes dont auto adjust but i rarely use the brakes when backing up. ie;backing out of parking space.

 

cancel that.

 

check to make sure the vacuum pump is working properly