I am not sure if the pump on the Volvo is an auxiliary vacuum or the only source of vacuum for the brake booster. Just starting to research this.
Trying to get more info like how are the vanes lubricated, a question Diesel911 asked. I am going to drop by a Volvo dealer and see what I can find out.

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1984 300SD turbo 126
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God made me an atheist and who am I to question His wisdom