Vito 639 servo and master cylinder

[zenman63]

Had a bit of a moment this week in the Viano, no brakes or very little.
It started with a strange dry sound and a fart like noise inside, it was like that a week then one day from parked, foot on the brake and into drive and it was off!
Pedal would pump up ok but went down very low.
Today had a good look and with the engine off and pump the pedal it would go down and then be hard and stay like that, star the engine and the pedal would drop all the way to the floor, I kept trying that and it got to the point it was just a hard pedal and no assistance, pedal would just drop.

Pulled the servo out and it has some fluid inside so I am thinking master cylinder.
The rubber boot inside above the pedal has blown off and seems dry.

Looking inside the servo seems ok, diagram is all ok but the white piston does look warn in the middle.

Before I look deeper could it be the vac pump?

It had lost some fluid but very little.

 

[Giantvanman]

On, for example, some cars, pedal drop can be due to the brake assist system or a faulty ABS block. If you aren't getting assistance, the servo itself or it's vacuum could well be the problem.
On a different tack, have you changed pads recently?

 

[Vitobrabus]

Doubt it's the pump. Losing the vacuum would just give a hard pedal. I had similar symptoms in the old 638 I had. That was due to a split hose. Easy to spot as there was a puddle of fluid on the floor. I would look towards the master cylinder letting by the piston.

 

[zenman63]

Thanks for the replays
ABS pump is very new, I did that last year.
I have a new servo and master cylinder coming in the morning so swapping both as its not that easy to get at, updating at the same time to 2014 spec.
Pads new and discs and fluid all rebuilt and painted callipers a year ago.
Some time now I have had a poor brakes, not as sharp as you would like so hopefully it will fix it.

 

[zenman63]

 

[zenman63]

 

[pulbex]

On, for example, some cars, pedal drop can be due to the brake assist system or a faulty ABS block. If you aren't getting assistance, the servo itself or it's vacuum could well be the problem.

On a different tack, have you changed pads recently?

i agree your opinion

 

[zenman63]

All done and back as it should be, so much better than how it was.

All upgraded to 2014 spec TWR servo and master cylinder.

So no idea what it was so changed both at the same time.