Hi Mike, I have 1995 318ti I just replaced the thermostat. The one that was in it had a small indent at the top to let a little antifreeze by, I replaced it with a German one that had no visable bleed hole or indent but had a arrow to point up. The German stat was bad, it may have opened once but failed from the beginning. Upper right hand hose as your standing in front of the car was hot, bottom left hand hose was cold, you could hear water boiling from upper hose, gauge went a tick past 12 noon. Third thermostat had a small bleed hole with a small rattle rivit in it. I wouldn't pull the stat you drilled, that was my next step.