Brake loss intermittently

[Edgingage]

Hi folks, 2011 Edge SEL here (205,000 km; ~127,000 miles):

 

I posted in general Brakes, Chassis & Suspension but I'm afraid this problem might be more common or specific to the 2011 Edge/MKX; that's why I'm posting here.

 

I just had a very scary event this morning: while driving in the city (TG!), approaching the lights my brake pedal went to the floor with no much brake action other than deacceleration.  As I was very close to home (TG again!) I kept going very slowly (with my emergency lights on), and once in a while I was "testing" (pushing) the brake pedal with the same result: very little resistance to stop the vehicle. 

 

I managed to get home without an accident. Once in my parking lot, I drove the vehicle back and forth (slowly) with the same result: brake pedal to the metal and no real break action, very little, if any.  I shut it off and called the dealer to explain the situation: they told me "you could probably not drive the car here", I said "yes, it's just a couple of Km away".  I drove it to the dealer; however, in my way to the dealer the brakes were working properly, I tried to reproduce the same thing (pressing the brake pedal at different intervals, speeds and pressure) and the brakes always worked as normal.

 

Hum, I told the dealer, now I have two problems: what about if you guys can't reproduce the failure I just had today.  And of course, I'm not confident to keep driving this vehicle without finding out what went wrong.  The dealer gave me an appointment for two days from now for they to "'check things around..."

 

As a background info, the brake booster was replaced about three years ago.  At the time what happened was the other way around: I had to literally step on the brake pedal to put enough pressure to stop the car even while driving slowly.  This time there was no resistance from the pedal.

 

So, my questions to you folks:

- anybody with a similar experience?

- if the brake booster was replaced three years ago, could it be gone so soon again?

- where should be the first place/part to look at?  This question is very important as the dealer didn't know where to start looking and I'm afraid they my charge me $200+ just for looking/trying (and not finding the problem).

 

And yes, I did check for break fluid leak and level: no fluid leaks; all fluid levels checked OK.

 

I'm lost; don't know where to look or what else to do.  Please help.

 

Thank you folks.

 

Chris.

Edited August 2, 2022 by Edgingage

[Haz]

I have offered my reply on the duplicate post in the Brakes, Chassis & Suspension forum, in order to facilitate future searches for information by topic.

 

Good luck!