loadstar w/ 345 stalling when brakes applied

[Kell]

when i step on the brakes the intake loses vacuum and stalls. pulled the hose to the brake booster at the oil bath air cleaner on top of engine. plugged the hose with my palm, engine doesnt stall when brakes applied. seemed like pretty strong vacuum on my skin through the booster. perhaps too much, interferring with air flow through the carb? is this a booster failure, or something else??

 

[Kell]

thinking it's probably a vacuum leak in the booster through one of the diaphragms or a seal. when i wait a moment before plugging the air inlet hose for the booster, and the block it, there's still strong vacuum. without a leak, i would think the air would fill the booster and there would be no vacuum on the inlet hose and air side of the booster. gonna pull it.

 

[Jon Hagen]

When you step on the brake, that air hose from booster to air cleaner should flow air for a second then stop as the diaphragm hits it"s travel limit.

If that hose sucks air as long as you step on the brake, then a diaphragm has failed and booster needs to be rebuilt or replaced.