The thermostat housing (there are now 3 different configurations requiring wiring adapters for sensors so do some research for what you need), the water pipe that goes from the water pump to the thermostat housing, and the water pump are all common sources.
I'll bet yours is the pipe. It's plastic and kind of a PITA to swap out, but doable in an hour.
https:// bimmercat.com/bmw/EN/search/selectCar/R60/CM/BMW+Cooper/ECE/11_4552
All 3 common parts to leak shown in that diagram (apparently I can't post links so copy that line and take the spaces out between // and bimmercat).
Sent from my SM-G950F using Tapatalk
I'll bet yours is the pipe. It's plastic and kind of a PITA to swap out, but doable in an hour.
https:// bimmercat.com/bmw/EN/search/selectCar/R60/CM/BMW+Cooper/ECE/11_4552
All 3 common parts to leak shown in that diagram (apparently I can't post links so copy that line and take the spaces out between // and bimmercat).
Sent from my SM-G950F using Tapatalk