The head gasket needed replacing on the old engine which had done 129,000 miles which isn't a huge amount but I didn't feel like spending £500 or so on fixing the head gasket. I found an engine that had only done 47,000 miles and had that put in which means a huge peace of mind as far as the engine is concerned.
Haha, thanks dude. Well, you would be suprised. The car I have (318Ci) uses a 2.0 petrol engine (engine code N42B20), which is, if I am honest, a very poorly designed engine.