Originally Posted by Markwarren39
How hard are the impellers to change? Where are they located? Thank you for the info
Assuming Mercruiser 454s, the water
pump">raw water pump is behind the lowest pulley on the engine
(next to the crank pulley, the one with belt only going between it and the crank pulley). I find it easiest to remove the belt and unbolt the pulley, then take the whole pump
off the engine
to open it up and change the impeller. Depending on how much room is around the lower part of the engine on your boat, you might be able to disconnect the hoses and pull the housing off the pump with it still on the engine.
If you need more, there are tons of videos online showing the process on various Mercruiser engines of that time period.