Re: Bendix Treadle Vac Study- Serioius Business!!

Posted by HH56 On 2011/6/7 14:54:24

I'm hoping Ross sees this and provides his expertise. He has seen many many more than I. The vacuum should not go away with a single pedal press after turning off the engine. Unless the main check valve is leaking, it should last for 2 or 3 depressions at least. A leaking check valve wouldn't cause your problem--just the reverse with a harder pedal depending on how much vacuum was available at that moment. With the periodic groan, it sounds to me as if one of the poppet valves has hardened and could be leaking or possibly a spring or something else could be broken in the vacuum section.