I was reading a post on here and wanted to share with all what it is and how to fix... I have a 150h.p Merc late model that I was going to sell. I dropped the lower unit, put a new pump in it, changed the oil and was ready to install. I could not get the lower unit to go into the power head and had changed many pumps before. I took a small light and looked all the way up and saw this metal "thing moving around" . Looked like a bushing of some sort. The marine shop told me what it is and that a cloths hanger would get it out. That could not happen as the hole is too small. The power head had to come off and then it was exposed... There is a bushing with a rubber seal that goes into the power head and fits perfectly into the bottom of the crank. Your lower unit splines go through it and I assume it keeps dirt out. Other than that function, I cannot see it doing anything else,. The marine shop says it would be ok to leave out but I didn't. I did put loctite on the new one , installed it and that was it. They come out often according to the marine shop and you will have to pull the power head which is not a big deal but you cannot get the drive up until it is taken out of the way. I tried everything to keep it from moving to install the lower unit but that was impossible. Just wanted to let all know that while it is not a big deal, it does involve pulling the power head. You just need to pull the bolts that hold the power head off. It was great to do save the money from taking it to the shop..Just get a cherry picker which I own given the many motors I buy and sell and of course the Merc ring tool that screws into the power head to attach to the picker. Hope this helps from being frustrated like I was encounting my first one.
