Hi everyone,

I've recently bought a Fiesta Ecoboost, one of the 2018 Zetec models. 

All was well but now when pulling up to my house and pressing the brake, it felt odd (almost loose). I live on a incline also and am 90% sure that the brake was on when i had already released it.

The main thing that definitely happens is the hissing noise when the brake pedal is compressed. When the ignition is on, you can keep pressing the pedal as usual (despite the hissing and loose feeling) but when the car is off, you can press it 2/3 times before it doesn't move; each time not going as far (not 100% if this happened before but never noticed it).

 

Any help? And also would you agree that it was be unsafe to drive down a motorway to work?

 

Thanks

Is it hissing only while the engine is running, not just with the ignition on? Possibly a vacuum pump or hose problem. If so you may not have full brake servo assistance so it might be wise to check locally that the brakes work well enough before taking it on a high speed road, or anywhere else for that matter, as this is probably a safety issue.

If it is a hose wrapping some PVC tape round it at the point of failure is probably safe enough to drive it wherever you need to get it fixed. It only needs to resist a 15psi negative pressure.

45 minutes ago, agraham said:

Is it hissing only while the engine is running, not just with the ignition on? Possibly a vacuum pump or hose problem. If so you may not have full brake servo assistance so it might be wise to check locally that the brakes work well enough before taking it on a high speed road, or anywhere else for that matter, as this is probably a safety issue.

If it is a hose wrapping some PVC tape round it at the point of failure is probably safe enough to drive it wherever you need to get it fixed. It only needs to resist a 15psi negative pressure.

Cheers. The hissing is there when when the brake is compressed both when the engine is on and off, just that with the engine off the brake can only be compressed a certain amount of times until it seems to lock and unable to move.

9 minutes ago, mattjohno10 said:

just that with the engine off the brake can only be compressed a certain amount of times until it seems to lock and unable to move.

That's normal once you have exhausted the vacuum in the servo after the engine has been running. There is no longer any assistance to help you with the pedal.

However I'm baffled about any other causes of hissing associated with the brakes when the engine isn't running as I understood that the vacuum pump is engine driven on Fiesta ecoboost engines.

 

Once the pedal has firmed up with the engine switched off is the hissing still there and if so does it die away and stop at some point?

I assume it stops hissing at some point. If you then turn the ignition on does it start immediately or only after the engine has run? I'm wondering if the hissing when  the engine has stopped is just the residual vacuum slowly dissipating through a small leak .

5 hours ago, agraham said:

Once the pedal has firmed up with the engine switched off is the hissing still there and if so does it die away and stop at some point?

The hissing is only as the brake is is being compressed. So when it is fully pressed or even firmed up it is silent.

I went out in it today for a small drive around the block to see how it is.

Honestly once driving and up to speed, it doesn’t seem to make the noise and actually the performance of the brake is not different. It however feels very loose and makes a clunky noise when returning to position.

 

Again though when pulling up the break had locked into place for 4/5 seconds and didn’t roll, despite being on an incline. Once it did start rolling it made a horrible clunky noise.

Without seeing it myself I have no idea what could be wrong but obviously it is not right so don't take chances and get a garage or professional mechanic to diagnose and fix it. Never skimp on brakes and tyres!