Originally Posted by C00LR
I had a good look today laying on the driveway under the bus and looked at the vacuum system. I found I have not one but TWO boosters under there. There is TWO tanks like Redbear was talking about for resivoirs. I DO have a vacuum guage. At idle the vacuum guage reads between 20 and 25... is it pounds??
Nope, not pounds, actually inches of mercury (usually abbreviated in/Hg). Believe it or not, this is the same measurement they use for barometric pressure when forecasting severity of hurricanes, etc. However, that is another story. The short answer is that 20-25 in./Hg is adequate for your vehicle since maximum vacuum you could produce under any normal circumstances would be about 30 in./Hg. That is as close to a perfect vacuum as you will accomplish without visiting outer space or a cryogenic vacuum chamber. From your description of sight, sounds, results, it would appear that your vacuum system and reservoir are working properly, now finish the repair on cylinders and such and you should have great brakes. Don't forget to do a final bleed after all repairs, and check that fluid is freely flowing from bleeder screws. If it isn't, you may also have collapsed lines which should be immediately replaced. I wish you the best, keep 'em rollin'.