Got my diaphragm and valve kits yesterday. Pulled the pump last night, and it was a serious mess inside. Both brake fluid and engine oil had gotten into the valves. When I turned the shaft by hand the valves made a sickly weezing sound not unlike those little animal-sound canisters. You know, the ones that make a cow or sheep sound when you flip it over.
Anyway, Got it all apart and cleaned it out with solvent and a scrubby. After drying I put it all back together, and got it back in the car for a test around the block. Only made a small difference in how fast the vacuum built up again, but I think I caught the problem early enough that it hadn't seriously failed yet. I'll have to wait until I get it warmed up, shut down for a few minutes, then restart to see if my symptom is gone.
Note on the rebuild kit: The diaphragm kit did not come with an o-ring to replace the one in the pump. It's a tiny little thing. The one in my pump was still solid, so I reused it, but wish I had known the kit didn't come with one. Also, I recommend getting a new o-ring between the pump and block. I measured both before putting the pump together, so I'll try to remember to post the specs when I get home.
Question: The Bentley mentions an oil connection on the pump. Mine wasn't connected to an oil supply, but I could see where the oil supply fitting had been. Looks like the design was altered when they produced the type B pump (part # ends in B), and VW had removed the oil supply. Anyone know anything about this?