1983 300d euro lose vacuum when step on brake pedal. hear a big whoosh sound. brakes very hard. tested vacuum 1-2 months ago close to the same at v pump and booster. can not turn off car with foot on brakes. let car idle for 30 seconds w/o foot on b pedal car stops fine and door locks work multiple times after car off. question is: is it the booster or where the master cylinder is attached to the booster.

Sounds to me like your Booster is the culprit and you need to replace it.

Here is a good tech article from Pelican Parts.

Pelican Technical Article: Mercedes Benz - Brake Booster Replacement


Power Brakes - Vacuum Assist - Explained - YouTube


Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works