Brake Booster Circuit

Can someone explain how the brake booster vacuum circuit works? Here is what I know: There is a vacuum pump driven off the front of the motor. Hose goes to booster at a 'T'. Hose extends to intake circuit of driver's side bank of motor with a check valve in the line pointing to the motor (away from the booster).

So what supplies the vacuum to the booster? The pump, the motor or whichever one wins?

My check valve seems sticky, it takes a pretty good blow or suck to open it. I sprayed some light lube in it but it is still not opening easily in the flow direction. It appears this check valve is NLA at the usual houses. Does anyone know a generic replacement part? I might just try NAPA.

My issue driving is that at idle I have no boost at all and have to stand on the brake pedal to keep from rolling. Otherwise, brakes are good.
Ken

 

I did a pretty through search of JEGS and came up empty handed. They had lots of check valves for fuel systems. The ones for brake boosters fit right into the booster which is not the function on our cars. Good site though.
Ken

 

I went to my favorite supplier for house and cars: McMaster-Carr. I ordered two parts. Catalog item 7933K35 looks he part in PVC but the crack pressure is too high. Catalog item 4610K17 looks like a winner and for $3.58 it is going to get a try. Crack pressure is negliglibe; it opens "by mouth". It is made of polyethylene which is resistant to fuel vapor and it is made for vacuum service.

I'll give it a try this weekend.
Ken

 

Price of the selected part is $12.28, breaks the bank.
Ken