Of course, you could remove the hoses to the intake and plug them. Then you should be able to blow into the vent hose and cause bubbling in the crankcase. Not sure that would be worthwhile, but it should work.

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Steve
2001 530i/5 S+P CDV delete/Akebono ceramic pads
M5 SSK/RedLine MTL/M5 rear sway bar/Bilstein HD
OSRAM CBI

BMWCCA Member #337964