Originally Posted by zip
Tom, assuming the engine is running?
Where is the impeller?
On engine, gear driven.
On a Cummins, it can be any of three different pumps - M72, GC1, 1716 (listed smallest to largest). All have different inlet and outlet sizes and run different impellers.
At 180 or 210hp, you only need the smallest pump, the M72. The GC1 is meant for the 250/270hp rating while the 1716 is meant for the aftercooled 300hp and up engines. I currently have a rebuilt 1716 on my boat (largest of the pumps but that's what came with it) but have also run a GC1 (for a couple of months while the 1716 was getting rebuilt). I have a brand new (due to warranty issue) in my garage as a spare.
Raw water pump is on the port side under the fuel injection pump.