I have a pair of 150 Johnsons on my Grady White and no problems up until now. Port engine was running great at 2500 rpm and suddenly shut down. I had a mechanic come out and he found two holes in the block right under the flywheel. One a 1/2 " hole that he could put a six " screwdriver into. The area behind the air intake had a lot of aluminum pieces and shaving in it. What inside the engine could have broken to cause this. The engine will start and idle.