Fiesta MK7 Servo Issues

[nathanphillips]

Hey there guys,

bit of a random one with the fiesta MK7 (2012,1.25). Driving into a car park and had to emergency stop, pulled up in space car was fine.

drive out of space, all four brakes giving a little bit of resistance, like I had left handbrake on. Continued to drive a short way and needed to rev the car to 7k to get it to move, with each application of the brake the pedal seemed to get harder.

 

called out the rac and he diagnosed a faulty servo, as disconnecting the vacuum feed from the servo instantly released the brakes, and the car ran with no resistance. Drove the car back home under rac guidance (with no servo assist as it had been disconnected) and took the car to the garage where they reconnected the servo, and the car has been fine ever since. The only thing the RAC guy did was spray some WD40 into the servo, just in case this would free up the servo. Garage are scratching their heads, car booked in tomorrow to have brakes looked over.

 

but does anyone have any idea or experience of this problem, and what would have caused, and possible resolution to the problem.

 

TIA

[dezwez]

maybe all it needed was a shot of wd 40 I would just keep a eye on it

[nathanphillips]

That’s what we’re all thinking too buddy, though I feel like I need an explanation 😂😂

[dezwez]

Just now, nathanphillips said:

That’s what we’re all thinking too buddy, though I feel like I need an explanation 😂😂

Normally when the go they go not start working again 😊 

[nathanphillips]

Yeah exactly what I was thinking assuming they are mostly built of some kind of rubber membrane once gone it’s gone 🤔

[isetta]

i assume it must have some kind of valve in it. The reason i say that is: if your foot is not on the brake, the servo does not pull the brake pedal down, when you press on the brake pedal the servo does provide assistance in pulling the brake pedal down, so there must be some kind of valve which lets the vaccuum apply to the diaphram when the brake pedal moves slightly. I have no idea what the valve is like / how it is constructed. I doubt a haynes manual would show the insides of a servo, I have not checked.

Could the ABS unit play up and cause such a problem?

Also I am thinking does your car have hill start assist? and is it turned on in the menu? perhaps it could have been that causing it for some odd reason. My 2015 Fiesta has hill start assist but I keep it turned off in the main menu. My view is that if I need hill start assist then I am not fit to drive at all.

[nathanphillips]

Hey isetta and thanks for the reply. I was thinking perhaps along the lines of an ABS fault, although there was no ABS warning light lit at the time, and I assume this would light up in the case of a fault here. There was just a traction control warning light which I assume was because the ecu thought that the brakes were on, so it was preparing the car for a skid. Unfortunately there is no hill start assist, I haven’t even got air con and I’ve exercise windows in the back 😂😂