Having a slight panic here - I will be contacting the garage first thing in the morning, but I wanted some suggestions/thoughts please:

 

I have a 9 month old Yeti (2.0 diesel, 2 wheel drive) which is under warranty.  Parked it up earlier, left if in gear and as I was sort of on the flat I didn't put the handbrake on.  Everything was fine, but when I came to start it I depressed the foot brake (which felt very firm), then the clutch - and the car started to roll back!  Scared the life out of me so I grabbed the handbrake and the car stopped.  I was on private grounds so I went for a slow drive, and the foot brake was stopping the car OK, but when I depressed the brake I could hear hissing.

 

Been googling things, and so far the hissing has come up with "brake servo", but I can't find anything that would explain why the foot brake didn't hold the car.

 

 

 

 

 

Having a slight panic here - I will be contacting the garage first thing in the morning, but I wanted some suggestions/thoughts please:

 

I have a 9 month old Yeti (2.0 diesel, 2 wheel drive) which is under warranty.  Parked it up earlier, left if in gear and as I was sort of on the flat I didn't put the handbrake on.  Everything was fine, but when I came to start it I depressed the foot brake (which felt very firm), then the clutch - and the car started to roll back!  Scared the life out of me so I grabbed the handbrake and the car stopped.  I was on private grounds so I went for a slow drive, and the foot brake was stopping the car OK, but when I depressed the brake I could hear hissing.

 

Been googling things, and so far the hissing has come up with "brake servo", but I can't find anything that would explain why the foot brake didn't hold the car.

I assume the servo was empty when you put your foot on the brake.......no vacuum assistance.

If you haven't experienced it before, it gives you a bit of a fright first time.

All disc systems are almost useless without the engine providing vacuum boost..........it's worth trying as an educational experience BUT it's like total brake failure, so choose your place v carefully.

So is the servo empty related to the hissing that I had when the engine was running - as in, there's a fault with the servo and that was why the brakes didn't work when the engine was off?  This is the first time I've ever experienced this on any car that I've had.

The hissing may be heard if you keep pumping the brake pedal, not otherwise.

Now you know why there is a handbrake! an ex army driver used to do the same thing,

just park with it in gear, until it popped out of gear and hit the car in front.

Without the engine vacuum pump running, and with the brake servo vacuum reservoir "empty", it is still possible to stop but the effort needed will be MUCH greater.  This is because with servo assisted brakes there is still a direct mechanical connection from the pedal to the master cylinder. A pedal which feels very firm and doesn't go down far would be indicative of no residual vacuum in the reservoir - this should normallly only happen (from gradual leakage past the seals) if the car has been parked up a long time.  It's therefore possible that your seals are more leaky than they should be, so it would be a good idea to get things checked out.  If the engine isn't running and things are quiet it's normally possible to hear a faint hiss just as the pedal is being operated.  With a full reservoir but the engine stopped you can apply the brakes perhaps 3 or 4 times before the reservoir is emptied.

 

I once had a car where the battery wasn't charging and the charge light had failed.  The voltage dropped so low that the engine eventually cut out as I was going along.  I managed to steer it into a layby, the brakes were still OK but with no assistance the steering was incredibly heavy -  it felt like someone had tightened a vice around the steering column !

Check the vacuum hose that goes to the servo, that may be leaking and causing both the hissing and the lack of servo assistance. Bit of an engineering disaster if it's failed on a 9 month old car, mind.