2017 Master Cylinder / Brake booster failure

[7GenTex]

My VIN shows no current recalls - 3/2017 build date..............(brake recalls (2) were 2014-2017 models though earlier build date than mine) Dealer instructions / parts pending (Q4 2020) for the 2nd recall.

Less than 5,000 miles on it (Yeah, I know - I have/had a company vehicle)

I estimate a 90% loss of braking effect - and the pedal had a mind of it's own.

Would feel / stop "normal", then to the floor / no stop, then normal, then to the floor.................was not fun - YIKES!

Brake fluid level was fine, no visible leaks, no warning lights / no chimes, nada..............YIKES!

Supposedly the booster is sucking brake fluid in from the master cylinder (though I thought that would cause a hard pedal.....?)

Booster On Emergency Backorder - no ETA - may be weeks.....................this sucks.


And, no hand release handle for the E-brake really SUCKS!

 

[FordTechOne]

Brake booster can’t cause a low pedal. What is happening is the rear seal on the master cylinder failed and allowed fluid to leak into the booster. You will need both a new master cylinder and brake booster to repair it.

 

[7GenTex]

Agreed............

 

[smurfslayer]

I’m glad you’re ok to type this. I’ve had a 100% brake outage on a Brand B motorcycle on Susten Pass coming into Andermatt. All I could do was downshift and lean harder. Only by the time I hit 2nd gear the fault cleared, restored braking and since lever and pedal were fully depressed we had a full lock up. I release the brakes, downshift to first, make the hair pin coast through the next 2 until I find a pull off. It’s better to be lucky than good.

I know this doesn’t immediately help, but I can’t recall any of us having this kind of issue before, so when it’s fixed, I’m betting you’ll never have a problem like this again.

 

[7GenTex]

......
I know this doesn’t immediately help, but I can’t recall any of us having this kind of issue before, so when it’s fixed, I’m betting you’ll never have a problem like this again.

Thanks - it was a bit hairy!

FYI - There are around 300,000 2014-2017 EcoBoost 3.5 F-150s currently subject to a recall for this. Latest build date for the recalls is Aug 2016...................currently.

Believe that could include some early Gen2 Raps......?

 

[7GenTex]

Weird.................

From the NHTSA:

https://static.nhtsa.gov/odi/rcl/202...0V332-1472.PDF

"Investigation of field return parts found the causes of the brake fluid leak to be
brake fluid contamination that could interfere with rear cup seal function or, to
a lesser extent, rolling of the rearmost cup seal in the master cylinder."


Also saw some issues on the interwebs regarding Canadian EcoBoost 3.5 F-150s having an issue with condensation contamination of the brake vacuum pump - related - who knows?

 

[Nibbl3s]

Brake booster can’t cause a low pedal. What is happening is the rear seal on the master cylinder failed and allowed fluid to leak into the booster. You will need both a new master cylinder and brake booster to repair it.

Had this happen on a Toyota. They replaced the master cylinder and a bunch of valves and told me it was fixed. I drove off and almost go into a wreck.

long story short Toyota covered most of everything and it was the ABS module that went bad and caused the pedal to go to the floor

 

[txgunsntrucks]

My VIN shows no current recalls - 3/2017 build date..............(brake recalls (2) were 2014-2017 models though earlier build date than mine) Dealer instructions / parts pending (Q4 2020) for the 2nd recall.

Less than 5,000 miles on it (Yeah, I know - I have/had a company vehicle)

I estimate a 90% loss of braking effect - and the pedal had a mind of it's own.

Would feel / stop "normal", then to the floor / no stop, then normal, then to the floor.................was not fun - YIKES!

Brake fluid level was fine, no visible leaks, no warning lights / no chimes, nada..............YIKES!

Supposedly the booster is sucking brake fluid in from the master cylinder (though I thought that would cause a hard pedal.....?)

Booster On Emergency Backorder - no ETA - may be weeks.....................this sucks.


And, no hand release handle for the E-brake really SUCKS!

rare issue. braking issues like a total loss like that are extremely rare.

historically braking systems are extremely reliable

 

[NASSTY]

Thanks - it was a bit hairy!

FYI - There are around 300,000 2014-2017 EcoBoost 3.5 F-150s currently subject to a recall for this. Latest build date for the recalls is Aug 2016...................currently.

Believe that could include some early Gen2 Raps......?

I don't think they started making Gen2 Raps until October.

I had that recall done on my old 2014 Tremor. I never had any issues with the brakes before or after the recall.

 

[hamster]

Brake booster can’t cause a low pedal. What is happening is the rear seal on the master cylinder failed and allowed fluid to leak into the booster. You will need both a new master cylinder and brake booster to repair it.

Same issue last December on '17. 3 wks for parts. Used it as an excuse to buy a '20 for a spare. Going to sell '17 one day.....been such a good truck that I hate to part with it.