i have 1999 328i ,and the heat stop working .and i m losing cooling water about 1 liter every 2 day and i don’t see any on the floor ,all i see some smoke but the car never went over heating
Sounds like a head gasket to me.
I am going to guess that you now have air in the heater core and therefor no heat. Bigger problem is that gasket. Have a compression test done.
Take your car to a shop immediately, and have them pressure test the cooling system.
If you don’t get this resolved soon, you are going to be looking for a new engine, or car, real soon.
BC.