Brake pedal going hard (Please help)

[dubstar81]

Hi guys
Just a quick one.
I was in a traffic jam today and i was doing alot of stopping and starting.
I noticed that when i pumped the brake pedal it went rock solid and the brakes wouldn't work.
But if i gave the engine a rev the pedal would go soft and the brakes would work again.
Now this is extremely scary and i would love it if anyone could help me out as i have no idea what is going on.

[martin1810]

You used the pedal too much and used up the vacuum to the servo. When you rev'd, it increased vacum and put pressure back into servo. Depending on how much pumping you did, this is not a fault. If it happens in normal driving get the servo and vacuum line checked.