280SL brake booster

[Thierry du Laos]

I have removed all the parts concerning the brake system. Checking and cleaning, I found some liquid in the booster.

I will replace the master cylinder seals, but when I cleaned the booster with gasoil: The control pedal side down side, i found the gaoil leaking through the booster.
Is that normal, and whose got a drawing showing the details of the system, booster side?
Thierry

[jeffc280sl]

There should be no brake fluid inside the booster.  As you know the master cylinder seal are bad and brake fluid has backed up and into the booster.  The brake booster provides a vacuum power assist to reduce brake pedal pressure when stopping.  You can search the web for vacuum assist brake boosters.  The design concept is the same in older american cars.

[Thierry du Laos]

Hi Jeff,

My problem is that I just bought the car and refurbish it all.
Dismantling, cleaning and checking the brakes, I found the liquid in the Master vac.
But, the config is that the 4 wheel brake pistons where stuck by corrosion, when I received the car. I think some guys have started the car and tried to brake. So with the power brake and pedal effort, the only way the fluid could escape is through the master cylinder is toward the Master vac.
Then, when I cleaned the Master vac, why it is leaking through. I understand looking at the schema below, that if there is not forces applied at both ends (brake pedal side, and master cylinder's) the valves are not seating properly and will leak. So there's no problem in this area.
Everything is going back cleaned, greased as before !!!!


Am I thinking the wrong?

[stickandrudderman]

If you have fluid in your booster then your master cylinder is leaking.

[sandcrab59]

Thiery:
Haven't talked to you in a while. How have you been?
I have experienced the same problem on other Mercedes cars I own.
1-You can hone out the master cylinder and put in new rubbers (which I have done in the past with success).
OR
2- buy a new master cylinder.
Tom Mrowka

[clembeauch63712]

 Hi Thiery; I would flush out that booster from both end in a position so it will drain out with a good quality brake cleaner spray can to flush out that brake fluid. If the booster is not working when reinstalled. I can be reconditioned by a company in CA. USA ; Power Brake Exchange Inc. They have web site; and are presently doing my 1963 230 Booster for $180.75 This company is a very big operation and in business  for 53 year. you might want to have it rebuilt at this time before reinstall to save time having to remove it  at a late date. online at Rock Auto has Centric brake parts new & rebuilt at very reasonable prices for your car it may be the route to go for new wheel cyls./ or re conditioned Calipers. Good Luck; Clem