Thought I would put up some info and pics on replacement of an impeller. This is on a 40hp Mariner. From what I understand this was built by Yamaha to Mercury specs, which is fine with me except finding parts has been a pain...:angry:. We dropped the lower unit last night, and had an impeller replacement kit, which of course turned out to be the wrong one. I think we've found the right one and ordered it last night. Here's a run down of what we did: Drain lower unit first...unless you want a mess. There are 6 bolts holding the lower unit on. I would suggest removing all but one in the center. Once you've done that there is a screw holding the shift rod in place in the lower unit. Remove that screw, then the final bolt holding the lower unit on. The shift rod has a rubber boot on it that slides into a tube, this will catch if you just try and pull the lower unit off. There is a single bolt holding the plastic tube in the lower unit, take that off, and the unit is now free it should drop right off. There are four bolts for the impeller housing, remove those, and with a little encouragement the housing should break free from the gasket. Ours was sealed on there pretty tight. Here are some pics of what the impeller looked like when we cracked it open. Pretty worn.