Locked Brakes.

[Sleek Lemur]

Hi everyone, I suddenly got a really hard brake pedal and all wheels locked. Then the pedal travels halfway down. Brake master cylinder I'm thinking?

[ja17]

Could also be the booster ?

[ejboyd5]

Disconnect vacuum supply hose from the brake booster to see if brakes release.  Open a brake bleeder valve to see if brakes release.  Report back on progress.

[Jowe]

Also check the lever #33 on this picture https://www.niemoeller.de/en/w113/w113/B044/424/ if it is stucked. This happened to me once. At first, I thought it was the master cylinder but then found the lever was stucked in the lower end. Clean and grease...

[Sleek Lemur]

Thanks to all! Have ordered a master cylinder in any case, as I only visit the car every fortnight. Will report back. Any other ideas gratefully received !

[Sleek Lemur]

Well, I returned to the car and all was well. No one mentioned to me that these cars can self-cure ! I have changed the master cylinder in any case and lubed the joint as suggested by Jowe. When the period of time we Brits laughingly refer to as summer is over, am going to send the calipers off for rebuild. £75 each sounds good value. Recommended to me by a member.
http://www.brakecaliperspecialists.uk/