Tom's '81 300SD has had an on going problem of the vacuum stopping resulting in rock hard brakes and the engine not shutting off when the key is removed . the HVAC also often defaults to the defrost mode , not fun in L.A. hot weather .
Because of how it does this , I felt the vacuum pump (the style with only one pipe connected to it) had a failing check valve , I grabbed one @ P-A-P and by the time he brought the car to me I'd carefully
" stored " it some place where it'll be safe & sound but I'll never see it again .
So ,I got another one and this time Tom decided to only wait a month or three , to - day when I unscrewed the steel vacuum pipe from the pump , part of the valve fell out and bounced off , not to be found . I found the steel parts , spring , retainer etc. all down inside the pump proper where I was luckily able to fish them out with a magnet .
I had my Mity-Vac tool handy and before taking it apart , the pump created 15" of vacuum , after replacing the broken valve it created 19" of vacuum (4" is a _LOT_ of vacuum) and the engine stopped quickly instead of slowly loosing speed and shuddering to a stop .
With the engine idling , I tested the various vacuum circuits by gently pinching them shut with some duck bill pliers , the brown circuit that shuts off the engine leaks as does the (green? I forget) HVAC circuit also leaks though not profesely .
He called a bit later to say it was better but still leaked out the brake's vacuum when idling , I'm thinking the entire pump needs a proper rebuild including new diaphragm and valves instead of just one used junkyard valve .
I'm also betting that the two rubber connecting hoses underneath the dashboard , are slimy with oil , blubbery and leaking vacuum out profusely .
We'll see .
-Nate
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