Hi all,
I have a 2006 F250 PSD that I cannot get the back brakes to stop sticking on. I have had it in the garage 2X, and have done it myself 3X. Every time it has had the Caliper's, Rotor's all slides and cages replaced and been flushed. I have put all new rubber lines on as well. (This seemed to clear it up for a bit, but it came back with a vengeance.) The last time all was replaced was last august. Again I put New Rotor's, Re-manned calipers, (I can not justify spending any more money, just to keep having the same problem's as new calipers). Well it is less than a yr later, and Calipers, Rotors, and pads are shot again. For now I just stuck some used pads in to get me by until I can find a solution. I'm not going to continue with $600 repair, just to do it every year. My slide pin's move freely, and I use CRC brake slide grease. (I have used stuff from the dealer as well, but my pin's have always moved freely).
Am I doing something wrong?
What about Reverse bleeding them?
Is it the master cylinder?
Is it the ABS modulator?
Could it be something in the steering pump?
Could it be in the distribution block?
It seems as though the rear lines always have pressure.
Edit: The parking brake backing plates, and the parking brake shoes/assembly's have also been replaced, Drivers side done by a ford mechanic, passenger side by myself.
Edit again: Only the rears stick. I did have to replace the front 1X, but that was because the Passenger side caliper pistons blew apart.

 

You stated the rear brakes always have pressure. If this is a constant the next check I would do is loosen the two master cylinder retaking nuts a turn and see if the pressure is relieved.

If the M/C was ever replaced its possible the aftermarket replacement is machined differently and the booster pushrod needs to be readjusted. Another issue I've seen is with some brake fluid leakage at the back of the M/C causes a rust buildup that does not allow the piston to return fully. Since the M/C has two circuits either of the above can effect only one circuit if the issue is mild enough.

A failed ABS module can also be at fault although it is rare. There is a check for this in the service manual and I have a copy of that in one of my Facebook albums.

 

How does one adjust the booster push rod? Do you think it might be easier for a fella that knows nothing about a brake master cylinder to just buy a new one (motor craft) and install it? Or would I have to adjust all that stuff anyways?
If I pull the 2 retaining nut's, will it be clear what I'm looking for? (I have never messed with the master cylinder on anything before.)
It seems as though the back is always dragging, the wheel's are always hot, sometimes the rotors actually flake apart.
Both rear brakes are constantly wore out. I never have problem's with the front, and the pad's and calipers on the front were replaced in 2011, and are over half pad yet. The rears (everything) get's replaced AT LEAST 1 time per year, sometimes 2x. I have been chasing this since 2010.
Edit: I don't have facebook, and don't know anything about facebook. I'm probably the only 34yr old on this planet that doesn't have an account with them! lol

 

Loosen, not pull, the nuts 1 turn and see if the clearance releases the brakes.

If it works you can remove the nuts can move the M/C forward to check if there is rust. If no rust then adjustment is needed.

 

I backed them 2 nuts off about 1 and a half turns, and am going to run it to work tonight and check the rear and see if they are hot. (They are a locking type nut, and I am certain they wouldn't back off, but for safety, I double nutted them. I also checked the pedal, and it feel's good yet.) If they are cool, I simply remove the master cylinder, and "tighten" that nut a turn or 2?
I did loosen it up enough to look behind it, and all seemed clean.
Can I run it a bit loose, or will it mess it up?

 

My thoughts were to just do that when there was an issue. It might be a little safer on the road if you put some flat washers between the M/C and booster, tighten the nuts and run like that. As long as the pedal travel feels OK.

If this solves the issue then back up the pushrod a little at a time. The more clearance the longer the pedal travel.

 

After i posted, I thought that putting washers for support might be a better idea. Thanks a million for the ideas. I will definitely keep ya updated. I wish I could rep ya again, but they won't let me.

 

If I help it's all the rep I need. Hope this is your issue and easily solved.

 

It sounds like there is fluid that doesn't want to return like it should. The clue is that both sides are acting the same. I would physically go by a dedicated brake shop and talk to someone experienced there, they can probably nail it. It's something between where the line splits to both rears and the master cylinder. Take a look at a schematic of it, I don't know how it is routed. Release the bleeding valve while watching the pad action to confirm that is is holding pressure.

 

Well a update.
The back wheels were touchable when I got to work last night. The passenger side was warmer than the other three, but better than normal. (Remember the passenger side need's a new caliper, as it is tore up pretty bad from the pictures above.)
Ex, there is no dedicated brake place here. However we are kinda experimenting, thinking the master cylinder actuator is too tight.
I'm gonna run it with the master cylinder shimmed for a week or so. (I will put a new caliper and pad's on passenger side, and just pad's on driver side rears). We will see what happens after I replace what I'm thinking is bad. (Caliper)
It seems crazy, but the truck seems to have more giddyup, and my pedal didn't change, or if it did, I didn't notice it. And I used everyday flat washer's to shim it. There has to be 1/16th-1/8th inch gap between the MC, and Hydro booster, or whatever the thing with all the hoses running to it is called.
1 more thing, the passenger side got used pads put on it to get me by for now, and I literally did that in the rain, in 15 minutes, so they were just slapped on, I didn't clean anything, or....well do it right, I was just trying to save my rotor some.
(Remember when I started this thread I said I'm not throwing any money at it, till I found the problem. That mean's That until I get this resolved, I'm not buying rotors again. The caliper, well they are not that expensive, and it is chewed up pretty bad. all the rubber boot's on it are funked up.)
Edit for the 3rd time: I can hear a whine now from the steering pump, is that because of the gap between the MC and the Hydro boost thing?

 

OK, possible improvement. You're right that the damaged left caliper could be confusing the results.

The spacing of the master should not cause any HB issues as the pushrod and internals will return to rest without any force from the M/C. But if you have some PS hose degradation, loose debris can cause some pressure relief and return issues with the HB along with pump noise.

Right now the advice I'm giving is based around your comments of trying to find a cause without throwing more money at this until there is a better foundation to an answer. HBs are not cheap. A dragging brake will hold back the vehicle, especially until boost comes up, as well as hurt mpg.

 

You make no reference of mileage on your 06. Does this rig see road salt? Any other history we should know about trying to help you trouble-shoot? Mainly what part of the braking system has been messed with? Is the fluid clear or black in the master?
If the calipers got cooked from excessive dragging replace them with a high quality new or reman. part…(not chineasium offshore junk!). Id think a faulty hydro boost would effect all four wheels not just the rears.
Test the “drag” on the rears right after several pedal cycles with the truck at idle. Do the rear tires rotate relatively freely? If not then immediately crack the rear lines. Then try to rotate. If they rotate freely after the line crack that will show you there's pressure not being released. It will spit quite a bit of fluid too so wear safety glasses and have rags handy.
This would indicate bad calipers or flex lines or the Master. The master is the last spot Id go to after exhausting the other stuff. I'm not familiar with hydro boost so if yours is so equipped I can’t offer more. That’s been discussed many times here. Do a search.
Verify the calipers are ok. Can you retract the pistons with relative ease using large channel locks or piston tool? If not the calipers may be bad. Are the slider pins sliding? If these items check ok then time to dig deeper
Next Id look at the flexible lines feeding the calipers. If someone in the past did a brake job and let the calipers dangle on the lines with zero support that can cause internal lining of the soft lines to collapse. Said collapse will prevent fluid from flowing backward in the line when the pedal is released, basically acting as a one way valve keeping the brakes fully or partially applied. This pressure will dissipate after a few minutes but not before burning up the brakes while you’re moving .The lines are a cheap fix and are often ignored. Do a complete 4 wheel fluid flush before you replace anything. A hand pump style bleeder is worth its weight in gold (think chemical bug pump sprayer…Jegs or Summit $60-70). I do a fluid flush on all my vehicles every 2-3 years depending on the miles.

 

I was thinking the same thing. He needs to know what part(s) only affects both rears.

 

I do it old school, and pump pump pump Hold, bleed, pump pump ........
Where I'm at with it right now. Everything has been changed several times, along with flushed several times. The calipers get destroyed from being hung. I'm fairly confident that everything up to the ABS module is good. (Again, I need a caliper for the RR, and pads on the rear)
At the suggestion of Jack, I shimmed the Master Cylinder, as he said that the ABS module's rarely have issues. (Not to mention these are really expensive, to just throw at the truck)
So if I rule that out, the only thing's left, are the MC, HB.
So far shimming the MC has netted me the result's I'm looking for. If it ever quits raining, I will get 1 new caliper, and new rear pad's, bleed it ALL again, and run it with the MC shimmed for a week or 2. If I don't have problems in that time frame, I will remove the MC, and adjust the actuator rod.
If I have problem's, back to the drawing board.

 

If all master cylinders and their piston stacks were made perfectly then nothing in the application package would allow only one circuit to not open the compensating port. But they're not, especially in the aftermarket. So a minor advance of the pushrod can cause only one of the two circuits to not fully open. A little more and both circuits would be closed off.

Adam in his first post stated he had changed all the hoses, the axle drop hose being the only one possible to block both rear calipers. He has also been into the caliper assembles yearly. The only other item to affect the complete rear circuit is the ABS controller which typically fails causing soft pedal with the rear circuit valve bleeding into the accumulator.

And PA, his location, uses deicers.

On edit, Adam posted while I was typing.