Hi All,

I'm tinkering with my 91 300D and I had some vacuum leak issues. I've buttoned up the leaks I had but I was checking the pump per the factory method as shown:

I get vacuum fine at the booster. If I put my finger over the line at the booster (or connect it) I do get 15-16" at the secondary connection at the pump.

Going by the test, my pump is bad but it doesn't appear to be from a logical stand point--at least mine lol.

Does the vacuum pump have two separate "stages" or "chambers" that should function independently and by failing this test, the separation is compromised?

What do you guys think?

(07.1-1843)

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