Low oil pressure/vacuum pump questions

[VWRacer]

I've been trying to find a reference to a post in which someone identified the role of the vacuum pump in cases of low oil pressure - can someone help me out?

Like many others with high mileage TD engines, mine has low oil pressure, especially when the oil is hot. I haven't installed a mechanical gauge, but the low pressure light comes on when the engine comes back to idle, for instance when I come to a stop sign. If I give the engine a small rev the light goes out. And it doesn't come on at normal engine revs.

I know about the role of the intermediate shaft, but I recall reading that if something in the vacuum pump is worn, that can also result in low oil pressure.

Can someone clarify this situation for me?

Thanks!

[QuickTD]

The vacuum pump has a gear on the end of its shaft. This gear is driven by the mating gear on the intermediate shaft. The vacuum pump has a slot or fork in the end of its shaft surrounded by a collar. The oil pump has a tab or blade that fits into the fork on the end of the vacuum pump shaft, this provides the drive for the oil pump. On high mileage engines the fork and blade joint can become worn and cease to drive the oil pump effectively. If you remove the vacuum pump you can easily inspect the oil pump and vacuum pump shafts for wear.

[VWRacer]

Thanks QuickTD...that's exactly the info I was looking for!