Merc 39 water pump removal

"Hi All!

I'm in the pro

"Hi All!

I'm in the process of replacing an impeller on my 1966 Merc 39 (3.9 hp). I purchased a complete water pump replacement kit but I can't get the bottom part of the original water pump to come off. Id there some trick to this or do I just need to apply more muscle to get it free? I'm afraid to pry on it too hard for fear of breaking it.

Any suggestions on how to get that sucker off will be greatly appreciated.

Thanks,

Jon"

"I hope you have the service m

"I hope you have the service manual. I am not sure, but if it is built like a 1960 10 hp and a 1955 Mark 25 I own, you will need a spanner-type tool to get the water pump cover off. It has 2 pins and a hole in the center that will go around the drive shaft. I am going to make one for the Mark 25 with 3/16" hardened steel dowel pins and bar stock.There is a similar nut in the lower unit prop shaft carrier/cover and we made a socket for the 10 hp by grinding a deep socket so 2 teeth were left which engaged the slots in that part."

The 3.9 is nowhere near the sa

The 3.9 is nowhere near the same as the earlier MERCS referred to above. Just ignore that info. There may be a flush plug holding the lower housing in---if not just pry up on it.Usually a new impeller is all that is needed to restore full operation of the pump.

Flush plug.

Flush plug.