hard brake pedal, seems no power assist - bad booster?

[fbody]

Well, when i got the truck, it had what appeared to be no booster assist on the power brakes. I replaced the booster with another (used) from a guy who said it worked fine, but again used part.  I have replaced the master cylinder, bled it first on the bench, no issues.  The brake pedal still requires that I press way too hard to stop the truck.  Pedal doesn't go to the floor or anything.

check valve, that simple? or still is the booster prob and I should buy new.  No leaks anywhere.

73 C20, 3/4 ton.

any thoughts?  thanks.

[VileZambonie]

Pump the brake and hold pressure on the pedal. Start the engine. The pedal should drop. -Report

[fbody]

pedal doesn't drop at all.  pumped it, held it down, started it.. pedal didn't move.  i guess that means booster?

[malibu795]

check vaccum lines from carb to booster -report

[fbody]

yep, plenty of vacuum.  pull line, plug it with a bolt, start engine. pull bolt, plenty of vacuum, just about dies.

[VileZambonie]

Replace the booster if you have vacuum at the check valve.

[fbody]

yep, replaced booster tonight, that was it.  no more rock hard pedal.  Back to power brakes.  thanks again.

[Irish_Alley]

a question about boosters didn't see the need of adding another post but theres not supposed to be a gaskey between the master cylinder and booster right?

[fbody]

there wasn't on mine.. and one didn't come w/ the reman booster either.

[Irish_Alley]

I didn't think so lol mine was sucking in air there so my booster is bad but I got some gasket seal in there for now rigged her right up lol