2010 535i belt torn causing oil leak

[Yaofeng]

My 2010 E60 535i had the belt partially torn last Sunday on the Garden State Parkway. It created massive smoke trailing behind me which I did not realize. A State trooper stopped me when he saw the smoke. I had the car flatbed home. I know it is engine oil because it is black.

I removed the cooling manifold as a unit (radiator, ac condenser, steering hydraulic cooler, transmission oil cooler) to replace the belt. The belt had the inside rib torn but still remained a loop driving all accessories. On the cooling circuits only the transmission oil circuit is not disconnected. The PS fluid and the engine coolant are drained. The engine oil cooling connections are separated but not drained. Did not see where the oil leak come from. I am trying to figure out the best way to test it. I am thinking to install the belt, install the cooling manifold without filling the steering fluid, engine coolant, naturally not the Freon either, start the engine for a minute to see where the oil leak is.

I know it is not from the crank seal. I had the engine removed in 2019 to replace the twin turbo and replaces all seals. The leak was on the top driver side (radiator area) as I opened the hood when it occurred that area was wet.

Appreciate anyone to have more insight.