MostlyHarmless

Guys

I am new on here, and would appreciate any advice you are able to offer

I have a 2011 F150 Lariat with the 3.5 Ecoboost. The truck has about 26,000 miles on it, so it's not very high mileage

I have had it for about 18 months and in the last 2 months have noticed that the brakes are getting very weak. It doesn't matter how hard I push the pedal the wheels will not get to the point of activating ABS - very scary on a couple of medium speed stops on Interstates where the brakes were really not up to the job required of them

I am pretty mechanically competent and checked the general condition of the brakes myself - pads and rotors fine, fluid levels fine, no leaks, brakes all operate and free off when the car is on a ramp and spinning the wheels. Also had my local Firestone do a free check and they also reported no fault found

I have read about the electric vacuum booster issues that some people have suffered, but if I am reading it right that is there to boost the brakes at low RPM to make up for the lower manifold pressure of a turbo engine when not on boost. I would not expect that to be my issue as I am having it at Interstate speeds when my engine should generate sufficient boost.

I am not sure if the fluid on the truck has ever been changed, but even allowing for some water retention by the fluid this degradation of braking power seems to sudden and too severe to be explained by water in the fluid (although happy to be proven wrong if that is the problem)

So I have two questionsL

1 - anyone else aware of these problems and can point me at a potential issue I could diagnose

2 - does anyone know of a good independent shop in the Baltimore area that really knows late model Ford Trucks. The dealers will just component swap until they resolve the issue and I am not sure I want to spend dealer money - I would rather give my work to a quality local independent

Thanks all

Mark

RLXXI

Brake boost is vacuum not pressure, that's why you have an electric pump, when your engine is operating under the pressure of the turbo (hwy speeds) you need that pump. When the turbo is not creating boost you should have vacuum in the manifold.

If the pedal travel is normal just really hard to depress, the vacuum pump is defective or has a leak in the line between the pump and the booster.

MostlyHarmless

Rnlcomp

Thanks for the reply.

I should have put that information in me original post - pedal pressure is normal, it feels like a "normal" pedal when I push it, just that it doesn't provide enough effort to slow the truck when I push the pedal

When the engine is turned off, the pedal is significantly harder and then softens up when the engine is turned on - that suggests I am getting vacuum assistance from somewhere!

Cheers

Mark

H-60 Electrician

Some easy things to check.


http://www.ehow.com/list_7166506_sym...e-booster.html

RLXXI

Yes, your engine has vacuum at idle as well as any other time where the turbo is not making boost, it's when you put your foot on the accelerator that the turbo kicks in and starts forcing air into the engine that creates pressure in the engine and the vacuum pump is required to provide that loss of vacuum for the brake booster.

MostlyHarmless

Rnlcomp

Thanks for that explanation as I think it is opposite from what I had understood

So when the Turbo spools up that increases the pressure into the engine (logical) and therefore leaves less vacuum pressure for the brakes - so the electrical booster is there to supplement that?

So the electrical booster is more needed at high engine speeds than at idle?

I had previously read reports of people struggling with the electric booster at start up, leading me to think it was there to help at low engine speeds.

So, in your opinion, the issue I am seeing at highway speeds could be related to the electric booster failing? Is there an easy way to diagnose that failure?

Thanks so much for staying engaged with me on this!

Mark

RLXXI

Yes you had it backwards, and it's an engine mounted, cam driven pump that supplies the vacuum booster with the required amount of vacuum to assist your brakes, very common problem among ecob owners.

I'm looking at the shop repair manual for a 2013, uncertain if it's an electric or cam driven pump on the 2011.

Hook up a vacuum gauge to the vacuum line going into the brake booster, see if you have at least 15-22"hg at idle, (subtract 1" for every 1000' above sea level.

If specified vacuum is not available, inspect the vacuum hose and install new as necessary. If vacuum hose is OK, install a new brake vacuum pump.

MostlyHarmless

Thanks Rnlcomp

So it is the electric brake booster on my truck

I have run some basic diagnostics and I am still a bit stumped as to what is happening as everything seems to function as it should:

- Engine off. Pump pedal a few times to remove any residual vacuum. Pedal goes nice and hard as it should and nowhere near sinking to the floor

- Turn engine on with foot on pedal and after a few seconds you can feel vacuum build and pedal goes "soft" with vacuum assistance and feels like it normally should

- Next check. Turn off engine again and pump pedal to release residual vacuum pressure

- Turn on engine and jump out of truck and round to front.

- Can hear electric vacuum pump running. Runs for about 15 seconds and then turns off. Not sure what one should sound like, but very quiet and sounded like a normal electric pump in operation

- All connections look OK and if the pump is shutting off by itself then I assume it is generating enough vacuum pressure to reach the correct pressure and shut itself off

I don't have a vacuum gauge to check the actual vacuum being generated, but on face value it seems that the system is working as designed. And yet the truck still stops like a horse and cart with wooden wheels and leather brake shoes :-)

Anyone got any ideas?

Thanks

Mark

RLXXI

Once again your booster is NOT electric, it operates on vacuum. The pump itself might be electric, I am un certain as the 2013 uses a mechanical pump and that's the shop manual I have access to.

In any event it's over your head and should be tested by a trained technician. They have the tools and know how to do so. It's one thing to jerk around with it running bad but if you can't stop the big pig you put your life as well as others in danger.

MostlyHarmless

Rnlcomp

Thanks for the advice - I am getting a vacuum gauge tonight to test the booster pressure - and thanks for the correction on terminology - you are correct, it is an electric pump on the 2011 which is servicing a vacuum booster

I understand from reading here that Ford ditched the electric pump after 2012 and reverted to a mechanical unit to due to so many failures

And to put your mind at rest - safety is 110% important. I am lucky enough that this is not my only vehicle, so it is parked up until I can either diagnose or get it to a shop. I will not be driving on the highway until I am satisfied the issue is resolved. Also have some land here, so can safely test the truck with no danger to others (or myself!!!)

Cheers

Mark