2004 525i question

[tl9015]

I just wanted to ask a question about my dads 2004 525i. There was no damage or accident to the car but yesterday, a white smoke came out of the exhaust pipe upon ignition. I have researched it and apparently the 5 series has a problem with broken head gaskets. Currently, there is no warranty on the car and he has given it to his friend's repair shop. He has updated us that the engine of the car seems to have a problem and it is expected that the whole engine has to be taken out for inspection. What seems to be the problem in the car? Is there a possibility of replacing the whole engine? It is expected to cost quiet a bit.

P.S. Currently my dad is using my 328i and I am carless!!