A friend in the slip next to me called this morning asking for help. He said, when he starts his engine (LF120 or 90) it has a loud knocking sound (he said clapping) and in just a few minutes the entire engine room is filled with smoke coming from the valve cover tube. That's about all the info I got at that time "it was early and I was still half asleep". We plan to have a look at it this weekend. Any ideas what is going on?