bmw 318i air lock and overheating

America is dying because people like you do not buy American cars.
l hope you have nothing but problems with the car.

This relates to the previous answerer is comments.
While American citizens r to a certain extent morally obligated to patronize American-made products like motor vehicles/cars, please remember that the American car manufacturers r also obligated to come up with vehicles that can stand up to worldwide competition.
This means cars & trucks that r up to date, fuel efficient, etc. etc.
Sadly, the big three had been more concerned with making money
on outdated gas guzzling trucks than on updating their product lineup
in tune with the times.
They have never learned their lessons from the late 1960 is & early 1970 is (during the first gas shortage years).
l would like to be patriotic too., but not a stupid patriot like what the
big three would like us to be, & this includes the last answerer.
EDIT:
Please clarify ur question. Be more specific about ur problem(s). Trash in = trash out.

One way u could get air locks out is to cold start the vehicle with either the rad cap off or the overflow cap off & let it run but stand back & close by to monitor it bec after awhile it will start bubbling & air will be forced out of the system just be sure not to add cold coolants or cold water add warm water or coolant if possible & over a bit of time the air should come right out , plus some systems have small air bleeder valves that much look like a air valve for a tire that u can open once the engine is warmed up with all caps on.

Hope that helps & best of luck.By the way those vehicles r pretty good cars & why not buy the better car if possible regardless who makes it.

helpful bob above has the exact answer l was going to give, same happened to me after a waterpump change