I finished rebuilding the water pump on my Merc 40 HP (model C40EO) boat today. All new parts were installed except base of pump. I could not get the old one out, so I left it in and installed all new parts in pump, including new pump housing top. After tightening the three nuts holding the housing together, the power shaft is very hard to turn by hand, I put marine grease on the new impeller and inside the impeller housing cup before installing. Before tightening the housing nuts, the power shaft was very easily turned by hand. But, as the nuts were tightened, it became increasingly harder to turn. I can turn it now, but it is hard to turn. Is that normal? This is my first DIY water pump rebuild, and I am ready and anxious to reinstall the lower unit on the motor and try it out in the run tank to see if the rebuild was successful. But I don't want to start the motor up if something is binding in the lower unit. What do you more experienced mechanics offer as advice on proceeding ? Thanks for your help!!
