augie62

Need to say Ford found my disappearing brake fluid - as I suspected, the master cylinder seal failed and the fluid went into the brake booster assembly. They replace both and I have my truck back in working order. Thanks for the support from FordService!

FordService

You got it, augie62! You know how to reach me if I can be of any help in the future.

Crystal

MHOWELL34

Mine was doing this, it seems like its always the master cylinder. Got a Dorman replacement off of amazon for a bargain (like 60 bucks). Not a drop has dissapeared! Always buy brand new, never get reman'd master cylinders.

Pull the master cylinder out, if it has a trail of brake fluid running down the back side its leaking and the booster is boiling it pretty much.

Kanleb

Hey guys, I did my front brakes this morning and I am having the same problem with my 2011 f150. Filled up the master cylinder and lost all the fluid within a couple minutes of driving. I work for a parts house so I ordered a master and booster. Do you guy suggest replacing both just to be safe? Or is it usually just the master cylinder? I plan on doing the replacement myself when the parts arrive later this week. Thanks in advance for the advice

raski

You are better off starting a new thread. However, you need to determine if the fluid is being lost down stream from the M/C or from itself. If you do not see any leaks, separate the M/C and booster to see if fluid is present. If the M/C is leaking, you should be OK with the booster and replace the faulty M/C. Don't assume, examine from the M/C all the way to each wheel before replacing parts. Start a new thread if you need further help.