I do not know the torque, somebody will chime in a give it to you.

I did, however, just replace my vac pump 2 days ago. I tightened the bolts with a 1/4" drive ratchet so I could not get too much torque on the bolts. I just snugged them up in a standard crisscross pattern. I may have went too far with one bolt but left it alone. It got tight then perhaps a little loose... I dunno. I was not paying much attention at the time. Too hot out for my brain to function

__________________
08 R320 CDI current

Past
95 E420
87 300D Turbo 5spd
90 300TE
83 300SD
85 300TD
92 400E
85 190D