The brake booster vacuum pump on my car starts to make a popping sound once the car warms up. The sounds speeds up with the engine rpm and there isn't any negative effect to the pump's performance. Is there some kind of "silencer" cap that is supposed to go onto the output of the pump? Thanks

Just remove the pump and get rid of the extra hose and t connections. Those pumps are a waste of time, and even Volvo dropped them. Maybe get a later cam cover so you don't have to cover the hole.
By the way RLC, the thing is driven off an eccentric on the camshaft. So much for your stream of conciousness conjecture.

Huh?

I have a 1981 244DL, B21A Engine, with a carburetor, Black Girling Brake Booster. There is a Whitish Oneway Check Valve that buzzes, only, as the valve opens and closes.

The hose from the Check Valve goes to a brass fitting on the Intake Manifold by the Oil Dipstick Tube.

The B21E Engine also appears to attach to the Inlet Manifold.

So, "Brake Booster Vacuum Pump" for that year model has got me stumped.

The Chilton Manual refers to it, but I still am not convinced it was for 1977 to 1981 cars, but Chilton also refers to setting Carburetor Mixture, but they refer to Figures 43 and 44, which are not Carburetors, but Fuel Injected Engines.

I have owned a 1977 B21E and a 1981 B21A, neither of those cars had a Vacuum Pump.

Haynes Page 146 refers to it and shows Figures 9.18 and 9.20 depicting the Vacuum Pump.

It should run off of the Intermediate Shaft, but that Shaft only has bearing surfaces for the Distributor and mechanical Fuel Pump, but has a blanking plate for B21E engines, for example, as they use Electric Pumps.

Personally, I think the Vacuum Pump is a good idea, because the Brake Booster alone barely does the job.