I have a 400 that has been underwater. I did not start it until I drained all the fluids and cleaned everything out. The good news is it starts and runs fine. The bad news is I have a "pank,pank,pank" noise coming from the engine that is not normal. I would like to know the possibilities as to what it may be. (valves????) I do not want to run it unless I am sure I will not cause any further damage.