Thats definitely not correct! At least the M57N (218 HP) engine was shiipped with swirl flaps: Intake manifold- Vacuum-controlled | BMW X5 E53 X5 3.0d M57N Europe

I would check the oil separator and at least the e39 had problems where the master brake cylinder had sucked water (water drain was clogged). I would check this, at leats to make sure...