I have an 8HP Mercury outboard dating from approx 1995. It has had very little use but the water pump has ceased to pump water, not surprising considering the age. The problem I have is that this particular model does not have a joint in the gear shift rod. I have unbolted the lower unit with reverse selected but it will only drop about 1 inch and won't move any further, the shift rod preventing any further movement. The rod passes through the water pump housing and the metal plate on top of the pump.The conventional wisdom is that the lower unit should be able to be pulled away but that is not possible. There was just enough room to get a spanner on the bolts holding the water pump housing and I was able to free the lower unit. I found that there is a circlip under the water pump plate which prevents the shift rod from being withdrawn. Also the shift cam on the end of the shift rod will not pass through the water pump housing either. It does not seem possible to re-assemble the water pump now without completely dismantling the unit and removing the motor so I can disconnect the shift rod under the engine. All this to replace a water pump impeller which should only take 15 minutes not 15 hours. Does anyone have any better ideas?