The valve on the ignition switch has a bleed function which, in the ON position, allows air to bleed into the shutoff valve.

If you reverse the vacuum connections to the valve, you will have vacuum leak problems, like my wife's car had when they replaced the ignition lock assy.
The car wouldn't shift until redline.
They reversed the vacuum hoses and it ran perfectly.

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Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.