water pump question...

[OMCboater]

my boat has a 120 OMC drive and I was just curious what exactly does that waterpump in the leg do? IE, why is there a water pump on the engine, and one in the leg? Do they do different things or just compliment each other?

Thanks in advance

 

[dgopetactical]

Re: water pump question...

The water pump in your engine that looks like one in a car is a water circulating pump that moves the water through your engine the pump in your lower unit is a raw water pump that draws fresh water in to your engine from your outdrive. Make sure you get your raw water pump serviced yearly ("impeller replacement etc.) to save you from overheating.

 

[OMCboater]

Re: water pump question...

So if I understand correctly, the engine mounted water pump is not capable of lifting the water from the lake so the leg mounted pump gets the water from the lake to the engine, then the engine mounted pump circulates it in the block and back out the exhaust?

(this is a raw water cooled system)

I'm thinking I definitely should service that lower pump as the boat has not been in the water for many many years and I have no idea what condition it is in. Can anyone direct me to a good write up on servicing the water pump in an OMC 400 stringer circa 1969?

 

[thrasher]

Re: water pump question...

You have perfectly understood the function of the leg mounted pump (I sometimes hear it refered to as a lifting pump) and the circulating pump.
I can't help you with the OMC manual, but I am sure someone will.

Gary

 

[WAVENBYE2]

Re: water pump question...

This is for my set up but it will help you better understand the raw water cooling system works.

 

[WAVENBYE2]

Re: water pump question...

Sorry let me enlarge it for ya.