Hello,
I posted this under a different post but now have a more specific question. Where could the 12 small, 3mm, ball bearings which I found in my '79 300td oil pump strainer have come from? There is also a part of their retainer in there. The size of the retainer would point to the bearing belonging to a shaft around 3/8"' in diameter.

The vacuum pump has been suggested. Any other ideas of how ball bearings got into my engine oil?

__________________
1985 300td 150k
1982 300sd (from 150-265k totally unconverted on wvo/diesel blend then stolen and crushed/recovered by a falling tree in a storm)
1980 528i 80k (currently recieving no love)
1985 Toyota 4x4 EFI 120k
1985 524td 90k (totalled on the SF bay bridge; a true crime)
1979 300td 188k
1979 240d 4spd 190k
1989 4runner 4x4
1989 325is
1991 Subaru Legacy
1985 Subaru Wagon
1972 Alfa Romeo GTV2000
1967 VW Bus
1996 XR600
1976 CB750k
1974 CB400f SuperSport