JP1341

iTrader: (1)

Did a few quick searches and couldn't find anything regarding master cylinder failures outside of the eco boost stuff. Maybe I didn't look hard enough? Anyways yesterday on my way to work I come to a stop sign and everything is perfectly normal. At the next red light I go to ease into my brakes to come to a controlled gradual stop but nothing happens. After looking for any external leaks of my fluid and checking my fluid level I drive around in an empty parking lot and discover that if I slam on my brakes ABS kicks in and functions as it should. However when I slowly apply the brakes the pedal will just continue to depress until I've nearly used up all available brake pedal travel before actually applying braking force to my wheels. 2016 XLT 5.0 I took it to my dealer and they said its my rear brakes, seized slide pins and uneven brake wear. I've seen seized slides and uneven wear before, I don't believe this is it cause I've never seen seized pins do this. And I'm out of warranty by 543 miles of course. Am I wrong in thinking its either my master cylinder or ABS actuator? Has anyone had this happen? Any advice on the 543 miles too? Know of any ways to bench test the components? I appreciate any help/ advice y'all have.

idrive

iTrader: (3)

The 5.0's have had a few failures the same as the eco's had a few years back.

You're a brave soul for driving the truck with the potential of brake failure very possible. The problem could be any of the above mentioned including their diagnosis which would surprise me.

Did the dealer say anything about being out of warranty? A call to the service mgr. is certainly in order. Approached the right way you just MIGHT get them to take care of it under warranty.

Best of luck, be safe and let us know the outcome.

Wrenchbender

With repeded pumps on the pedal can you build up enough pressure to Stop the Truck 50to 75% go to the fronts to stop the Truck sounds to me that the Master Cyl is bad are you loosing any fluid some have leaked Brake fluid into the Booster.

JP1341

iTrader: (1)

I'll have to double check the fluid level tomorrow when I pick it up cause I didnt think about leaking into the booster. This dealerships whole attitude has changed now that I'm out of warranty. They want me to spend about 500 in parts for the rear brakes before they will troubleshoot anything further to "rule that out as a possibility" even though they have already freed up the slide pins. So I'm going to wait until after rush hour and go to another dealership not but a few miles away cause the brakes do still stop me after I use up almost all of my pedal travel.

tvsjr

Please let us know your route of travel and expected travel times, so us responsible drivers can stay out of the way of the guy driving his F150 with *known* *major* brake issues.

Flamingtaco

I'd suggest bleeding the entire system before proceeding further. Eliminate the possibility of having air in the system.

I haven't done a brake job on my F150 yet, but most Ford calipers have replaceable slider pins. They are relatively cheap if you replace them yourself, no so much if you have to pay a dealership their labor rate. If you're out of warranty, I'd find a non-dealership shop that's also not a brake specialist to do the work if you don't want to.

Moist of the time, the pin grease has firmed up due to heat and never replacing it. You can wrangle the pin out and clean the grease off with brake cleaner and a green (3M) scrubbing pad. Fill the pin holes in the bracket with the cleaner, let it sit, then use a thin screwdriver to slide thin strips of pad into the holes, then spin the screwdriver.

If the pins or seats (holes) have rusted a bit, scrubbing them with the green pad typically removes any material that is causing interference with movement of the slides (as the process of rusting causes the loss of material). In a few bad cases I've taken a wire wheel to the pins successfully.

Any time pads are replaced, breakdown the pins, clean, lube, and install new boots, and clean the piston seal. Do this, you will never have a problem with them unless a boot is torn by debris (or there is a mfg defect).

Every 100k, I install a new cylinder seal. They will probably last to 200k, but I don't prefer to take chances with accident avoidance systems.

JP1341

iTrader: (1)

I bled the system about a month and half/ 2 months ago when I put my gorilla lug nuts on (I find it to be good practice to every 2-3 years flush and bleed your system) when I did the fluid was just a bit discolored but not bad. Afterwards my pedal felt great no complaints etc and I had not noticed any change in brake force required until the other day between the stop sign and stop light on my way to work when it was all of a sudden as if someone flipped a switch. I also had not noticed the seized slide pins but took note that with amount of pad left I should consider brake change in about a year ish. Called the other dealership before going and they were booked solid with no loaners available so before I turned in my loaner to dealer #1 and picked up my truck I went to dealer #2 and purchased a master cylinder. The parts guy there was cool and worked with me to get the master and couple bottles of dot4 for about $150. So this weekends project is bench bleeding new master and installing it then bleeding whole system again. I'll update if that fixes it or not luckily weather is nice so I'll just ride my bike to work today. I appreciate yalls advice, While I've got wheels off bleeding everything I guess it would be a good idea to inspect and lube all my slide pins.

JP1341

iTrader: (1)

Well for those that are interested it took me a lot longer to do everything than I originally anticipated. The brakes are working better than ever now which makes me wonder if my master was a slight dud from the factory. The brakes never felt bad, certainly better than my old 94 f150 but not as good as they do now, it requires so little input and I can easily feather the brakes to come to a nice controlled stop and very little pressure to hold at a red light etc. If I can manage to dis assemble the old master without ruining the ability to determine failure I'll update incase anyone is curious like me. If I ruin it.... oops. Thank you to those that offered advice etc. Cheers.

idrive

iTrader: (3)

Glad it all worked out. Always glad to see a thread such as this updated.