I’ve replaced the coolant expansion tank on my 2004 530i. Is there meant to be plug where I’ve circled it in the photo? If so what can I use to block it up? I’ve thrown out the old expansion tank and didn’t notice a plug on it

 

You were probably supposed to transfer the blind plug over from the old tank. Just order a new one, I believe it's p/n 11531436850.

 

Thank you 🙏🏽,