Bad booster just give you a hard pedal and stalls the engine, won't make the pedal go to the floor.

If you can recover the brakes by a quick pump, it's for sure the master cylinder. Rebuild kit is cheap, job is easy if you can find one, sometimes you can't and have to replace the MC instead. Do so at once -- rebuild or replace.

I would also strongly recommend new brake hoses and caliper rebuilds. The caliper rebuilds are easy when they aren't stuck yet, and if the hoses are hard and starting to crack, so are the piston seals and dust boots.

You will be amazed at how good the brakes are when you get done!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!