We were faced with a dilemma related to the brake booster. It worked perfectly well but the outside finish was poor and needed re-plating. Normally this would require a full dis-assembly and re-build but we decided to try something a little different. You see the brake booster is a chamber that is air tight and operates in a vacuum, so we figured if air cannot get in then neither will any fluid during the plating process assuming that it is sealed properly.
So we sealed it using high density polyethylene plugs we made and some old radiator hose (that explains the curve; there is no technical reason other than it is what we had available). After sealing it we decided to both test our plugs and the condition of the brake booster itself. Using a simple vacuum pump we fed in the same kind of vacuum the engine would make and let it sit for 10 minutes. With no drop in pressure (or increase as the case is) we knew it was well sealed.
Next it is off to the plater to confirm if the theory works. Once back we'll test it again and if the numbers look good then it is back on the car and off to the next task.