The original booster on my '73 Dart has a leak: sometimes stepping on the pedal results in a quick stop, and sometimes it results in a slow stop accompanied by a high, rough idle and a hissing noise.
So I bought a new old stock booster, which arrived promptly and certainly does look nice. Installed it this morning — looks like I'm going to need a master cylinder; this one's begun to leak backward past the piston. Hopped in the car and started it…
…Whoops. Sometimes new old stock parts work like new, and sometimes they work like old. This one's the old kind; stepping on the brake now results in a high, rough idle and a hissing noise each and every time. D'oh!
The weird thing is that the front half of the booster does hold vacuum. I ran the engine, shut it off, and pulled the check valve out of its grommet: WHOOSH! The check valve works correctly. I put it back in, started the engine, stopped it, then touched the brake pedal: Fshhh! So I'm not sure where the leak is, but it's in there somewhere. Guess it's time to get with John Stuart Power Brake and have either my original or this new-old one rebuilt.
