Loss of brakes on a morning.

[JohnnyW202]

When I start my 98' C200 up first thing on a morning, the pedal is hard and near the floor, only after revving the engine and pumping the brake will I get a decent feel, the flexi hoses are new and there are no leaks, the master cylinder upto the max mark too.

I'm guessing it's a problem with the power brake booster, looks expensive as the car has BAS!

Any ideas, would vacuum leaks elsewhere (door locks, boot etc) deplete the system to cause this? I know there should be a check valve on the end of the rather brittle looking vacuum pipe that runs into the side of the throttle body and I've clean this up and it rattles, but still the problem presists... quite annoying as I near keep going straight through my gateposts!

 

[grober]

Unbolt the vacuum pipe from servo and manifold . TEST THE VALVE BY BLOWING THRO IT IN BOTH DIRECTIONS. Should only flow from the servo to the manifold direction . Otherwise renew the valve.

 

[WOODYTHEWISE]

I used to test the servo by pumping the brakes prior to starting the engine,keep your foot on the brake,start the engine,the brake pedal should move dawnwards,if it did not it was a sign the servo was U.S.