HELP! from a Ford tech needed - dragging brakes

[idvette]

You've done a pretty thorough job of troubleshooting so far. It's certainly not the master cylinder. The master has 2 lines coming out of it, 1 for the front, 1 for the rear. You would have consistent issues with 2 wheels, not 1. How is the pad fitment in the brackets? You mention hardware is new, but not the condition of the pads and caliper brackets. If the weather there is anything like here, rust can build up behind the pad slide clips and on the pads enough that the pads become tight and stuck in the brackets. If you can't move the pads by hand, remove them, clean the slide surface of the pad, remove the slide clips and remove the corrosion on the bracket. I always clean the clips and lube both sides to prolong the reoccurrence of the issue. This is cheaper than throwing parts at it, and will rule out everything except the abs module. It is possible (not common) for valves to stick on the hydraulic side of the module, but you'll usually get codes or a light in the dash. Hope this helps!

[rock]

Did you talk to Scot?

Rock

[CVX20SPRINT]

Ok I'm not a Ford guy,but have been a licensed tech for a long time and IMHO brake calipers don't hang up intermitantly.They either get to the point of hanging up and stay that way until fixed or they don't hang at all.Even a collapsed hose will be pretty much consistant once it goes bad.Like idvette stated if there is only one front line coming from the master then both would be hung at the same time.That to me pretty much points to the ABS Module.People tend not to change brake fluid regularly like they do on motorcycles,so you end up with moisture in your system and there are a lot of small valves and orifices in the module where the crap can gather and hang things up.JMHO.

[davemvegas]

you are over thinking it. jack up wheel that is dragging while it is still hot. open bleeder. if wheel still dragging it is the caliper. you cannot get a steel piston for that truck so you are stuck with the phenolic piston that is a known problem on ford trucks. by some chance opening bleeder frees up the wheel than hose would be your most likely problem.

[idvette]

You'd miss stuck pads with that diag. Plus the calipers have been apart and inspected. If they retract (pistons go back in their bores) they're not the root issue. Stuck pads or hydraulic module haven't been ruled out yet, everything else has by the sounds of it. Not to be cocky, but I am a Ford tech and I see stuck pads multiple times daily. Think I've only ever changed 1 hydraulic control unit.

[Sonik]

Ok boys-n-grilles, long day today but I feel we have come to a solution. I was confident that all the hardware and sliders were good going in and as I said, I had new calipers waiting on the bench last night if it came to that....Well, today I decided that given the minimal investment, <$60.00/per reman bosch oem caliper) it was the most likely culprit given the (advice here) and previous parts replacement. I have four 10-15 mile vigorous road tests on it now over a 3-4hr time period and no signs of dragging as of yet. BUT, the pedal is still spongy and I feel pedal travel is excessive...I've put almost 3 qts of fluid through it during the multiple part replacements and there is no evidence of air in the system. Truck has been more or less this way since I bought it in 2005.

I had a tech buddy bring a snap-on scan tool over to run diagnostics on the ABS module. It actuates all 3 channels in the circuit ( in/out solenoids on the LF, then RF, then rear circuit which is a single channel), and then exercises the motor. I thought that if there was an issue with any air pockets or junk in the seats within the ABS module, this may/might purge and of it downstream to be bled later. Test was run several times and bleeding was done several times. Pedal remains spongy and travel is, again to my tastes, excessive....but it will perform an ABS stop, all the time, every time given the proper amount of coaxing.

Calipers were original OEM's and had never been replaced so my initial observations when broken down were obviously incorrect. And yes, I was probably over analyzing/complicating the troubleshooting process on this brake systemn as has been said.

More to come when I work the soft pedal issue........

[transomstand]

Sounds EXACTLY like the junk I drive. Just replaced my 6TH caliper since 2009

[RX4SPD]

you need to perform an abs service bleed there is air trapped in sys if its still spongy you may have to use a power bleeder get the air out I have been a ford tech for 10 years and those truck are known for those calipers getting stuck plastic+heat=retarded if you have any questions just shoot me a pm

[Sonik]

Ty for your input RX. The general concensus has been just that, trapped air....which means it has been this way since I bought the truck in '05. The caliper swap did solve the drag and I should have just replaced them first in hindsight instead of convincing myself the problem was further upstream. I'll do some digging on the service bleed procedure, try to score a power bleeder, and see what kind of damage I can do with it. TY for the input gents.....


EDIT: Something I probably should have mentioned previously is the fact this truck suffers from the dreaded double pump syndrome as well. 1st application of the brakes will stop the truck no problem but a quick release and reapplication of pedal pressure firms it up a BUNCH. This is why I kept going back to the master cylinder as the possible culprit early on. Not sure if this changes anything or not, but as I said, it stops fine without a double pump, the pedal travel is just excessive in my mind.

EDIT#2: For the possible benefit of someone else in my shoes, the ABS Service Bleed procedure is as follows:

If equipped with the 4 wheel anti-lock brake system and the Hydraulic Control Unit (HCU) has been replaced or is suspected of containing trapped air; bleed the brake system using the procedure below. Conventional brake system bleeding cannot remove the air trapped in the lower portion of the HCU. If a spongy brake pedal is present and air in the hydraulic control unit is suspected, use the following procedure:

1. Bleed the brake system as outlined in the conventional bleeding procedure.
2. Connect a New Generation Star (NGS) tester or equivalent scan tool, to the serial data link connector below the instrument panel as though retrieving codes.
3. Make sure the ignition switch is in the RUN position.
4. Follow the instructions on the NGS screen. Verify correct vehicle and model year go to the "Diagnostic Data Link' menu item, choose ABS Module, choose "Function Tests", and choose "Service Bleed."

5. Bleed the right-front wheel as follows:
---A. Open the caliper bleed screw and pump the brake pedal for 3 seconds. Repeat the procedure again.
---B. When the fluid runs clear, begin the program and continue to pump the brake pedal.
---C. Continue bleeding for approximately 1 to 2 minutes after the program ends and then tighten the bleed screw.
6. Repeat the bleeding procedure to the left-front, left-rear and finally the right-rear wheel.
7. Remove the pressure bleeding device and adjust the brake fluid level.
8. Road test the vehicle and check for proper brake system operation.

[albypine]

Yea was going to tell you that yesterday that you have to bleed lone brake line first but I was busy and you had inlaws date day

[Deznuts3570]

Ty for your input RX. The general concensus has been just that, trapped air....which means it has been this way since I bought the truck in '05. The caliper swap did solve the drag and I should have just replaced them first in hindsight instead of convincing myself the problem was further upstream. I'll do some digging on the service bleed procedure, try to score a power bleeder, and see what kind of damage I can do with it. TY for the input gents.....


EDIT: Something I probably should have mentioned previously is the fact this truck suffers from the dreaded double pump syndrome as well. 1st application of the brakes will stop the truck no problem but a quick release and reapplication of pedal pressure firms it up a BUNCH. This is why I kept going back to the master cylinder as the possible culprit early on. Not sure if this changes anything or not, but as I said, it stops fine without a double pump, the pedal travel is just excessive in my mind.

EDIT#2: For the possible benefit of someone else in my shoes, the ABS Service Bleed procedure is as follows:

If equipped with the 4 wheel anti-lock brake system and the Hydraulic Control Unit (HCU) has been replaced or is suspected of containing trapped air; bleed the brake system using the procedure below. Conventional brake system bleeding cannot remove the air trapped in the lower portion of the HCU. If a spongy brake pedal is present and air in the hydraulic control unit is suspected, use the following procedure:

1. Bleed the brake system as outlined in the conventional bleeding procedure.
2. Connect a New Generation Star (NGS) tester or equivalent scan tool, to the serial data link connector below the instrument panel as though retrieving codes.
3. Make sure the ignition switch is in the RUN position.
4. Follow the instructions on the NGS screen. Verify correct vehicle and model year go to the "Diagnostic Data Link' menu item, choose ABS Module, choose "Function Tests", and choose "Service Bleed."

5. Bleed the right-front wheel as follows:
---A. Open the caliper bleed screw and pump the brake pedal for 3 seconds. Repeat the procedure again.
---B. When the fluid runs clear, begin the program and continue to pump the brake pedal.
---C. Continue bleeding for approximately 1 to 2 minutes after the program ends and then tighten the bleed screw.
6. Repeat the bleeding procedure to the left-front, left-rear and finally the right-rear wheel.
7. Remove the pressure bleeding device and adjust the brake fluid level.
8. Road test the vehicle and check for proper brake system operation.

Jeff u missed it cuz. Its the kineveling pin that goes into the kawobbling hole that powers the friction reducer that in turn sends signals to the continium transfunctioner and sends a signal to the flux compacitor. Serious stuff! Im just messing. Wish you the best cuz lol!!!!!

[Motv18]

Heh i was going to say your booster is getting goofy one of the more overlooked parts. Sounds like you got it though.

side question how is the rear break where? This dubble pump condition sounds like the brake balanger is failing forcing all the braking power to the rear wheels. The long pedal spongy feel is from the calipers not retracting fully. If the rear pads are fairly ate up it will take forever for the balancer to start engaging the front brakes. The need for the second pump.

[Sonik]

Forgot about this thread. With some help from a guy much smarter than me, the conclusion is the HCU (hydraulic control unit) for the ABS located on the frame rail below the master cylinder. There is a simple test to determine health that involves removal of 2 inspection plugs on the backside (towards fire wall) of the HCU and inserting a piece of wire or straightened paperclip into the plug holes. The wire bottoms out on the top of the relief valve pistons. You then apply the brakes and if the HCU forces the wire/clip out, the HCU is at fault as these should not move within their bores unless acted upon by the ABS motor and control circuit.

The double pump simply moves enough fluid to hold the pistons at the limit of their travel, and beyond whatever allows pressure to bleed off, which is why the pedal firms up and brakes function normally. What was happening in my case, is that the rear brakes were bleeding off pressure and almost all of the braking force applied was from the fronts only. I haven't swapped the part yet but will get to it eventually.

[albypine]

Government job must be making you lazy

[Motv18]

Cool, good to know i had it backwards been forever since class in oh three