Just had my Regal 1800 1.7 mercuriser diesel delivered this week - I got it tested prior to buying and was told she was good, got here Wednesday went out for about 2hours and she was good. I then went out flat out this morning for an hour... all good... then we were going at about 10mph for about 4 hours and then went to speed up past 3000rpm and I could hear/feel a loud bang . slowed down she was fine but everytime I sped up same problem, I also had the same issue in reverse? the engine was purring nicely so maybe a drive issue - any ideas? hoping not serious as its meant be good! also the prop has abour 2mm play in itback and fourth is that a problem? any ideas?