Diesel Place banner

1 - 4 of 4 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
Hi everyone,
I have a 2006 F250 Powerstroke with a 6.0. I traded my uncle for it not too long ago. All four brakes are locked up, I have to put the truck in 4X4 just to move it. The front brakes seem to be worse than the rear. Whether the vehicle is running or not, the brakes are applied. My uncle replaced the rear calipers, brakes, and hubs. He also replaced the master cylinder(brand new). I suspect the issue is the hydrobooster, but from my research, I haven't found any evidence to support my suspicion. I know there is a fluid leak on the hydrobooster, but not too bad. Would the hydrobooster engage the brakes even if the truck is shutoff? Could it actually be the hydrobooster? Any advice/direction would be greatly appreciated!
 

·
Administrator
Joined
·
16,738 Posts
Welcome to DieselPlace
(y)
 

·
Premium Member
Joined
·
17,935 Posts
Loosen the master cylinder from the booster (2 nuts) and see if it goes away. If the master cylinder is even slightly depressed, the brake fluid cannot return to the reservoir.
Something could be holding the pedal slightly down, the booster could have debris, the booster can be the wrong part number, or the master cylinder could be the wrong part number.
Regardless, if you mate the master cylinder to the booster, the flange should contact before the pushrod touches the piston in the master cylinder.
 

·
Registered
Joined
·
5,594 Posts
Ya all 4 unless its some really wacky ABS failure would just about have to be at the master cylinder. As mentioned above something isn't letting it all return. Separating the master and the booster is a good idea. Lines should have enough flex in em you should be able to move it far enough forward to see whats going on there. If they don't release just my moving it look in and see if you can see if the piston has returned. Most MCs have a snap ring that the piston normally sits against. If its not touching that its either a dud or has some crud in it.

If things go back to normal when you split them then I would be looking for anything out of place especially related to the pushrod. Sometimes those don't come with the new one so you have to transfer over the old one. Some I think have a metal star washer sort of thing that keeps it centered that isn't the easiest thing to transfer so maybe someone got lazy and didn't transfer it? Also try and measure how far it sticks out and compare that to where the piston is resting. Maybe its the wrong MC. Maybe something simple like gas vs diesel and the resting position of the piston?
 
1 - 4 of 4 Posts
Top