[TheBmwGuy430i]

I have 2017 BMW 430i with around 180 000 km. The Car drives great, I dont feel any problems. The other day I went to start it after the car was sitting for the night. The car tells me to refill coolant. I go open the hood and I find the coolant leaking from the cap of the expansion tank. Overall I have been refilling it every other day. One Day I refilled it in the morning and I drove about 20 km and I slowed down and the message about refilling coolant popped up again and steam was coming out from hood. I opened the hood and let things cool down and drove off. I suspected the water pump to be the issue so I replaced it. I havent drove it yet I plan to drive and see how things go. Also, I have not detected any other coolant leaks from anywhere else other than the cap. The car drives fine and the temperature gauge functions like normal. Has anyone had this issue before? If so can anyone provide some guidance.