Is it necessary to change impeller in Alpha one drive with closed cooling system

[capecodder116]

I have a mercruiser 260 engine with closed cooling system. I replace the raw water pump impeller for the engine every other season. My question is how often should I be changing out the impeller located in the alpha one drive as this is not used to cool the engine (blocked off at transom) is it really necessary at all.

 

[Don S]

Re: Is it necessary to change impeller in Alpha one drive with closed cooling system

Absolutely, that's what cools the antifreeze. Kind of like the air flow over a radiator in your car, but water is used because there is no air flow in the engine compartment.

 

[capecodder116]

Re: Is it necessary to change impeller in Alpha one drive with closed cooling system

The raw water sea pump which functions via an auxiliary v belt pumps the seawater into and thru the heat exchanger to cool the anti freeze for the motor. I am asking about the necessity of the impeller located inside the alpha one drive. This appears to be plugged off at the transom and therefore not pumping water anywhere. So is it necessary to replace this impeller at specific intervals or can I just remove and discard.

 

[agallant80]

Re: Is it necessary to change impeller in Alpha one drive with closed cooling system

Are you sure the system is fully closed? Some of those systems only close off the block.

 

[haulnazz15]

Re: Is it necessary to change impeller in Alpha one drive with closed cooling system

If you have a belt driven raw water pump (not the engine circulating pump), you can remove the impeller in the drive if you want to. I would advise it actually, to keep any water pressure from being in the plugged water line. However, you will still need to keep the raw water line plugged as there is still a path of water to get into the boat (albeit very minor probability).

 

[Don S]

Re: Is it necessary to change impeller in Alpha one drive with closed cooling system

Mercruiser recommends you leave the impeller in the drive, this pushes water through the upper for cooling while on plane.
They do show to cut the hose just in front of the bellhousing to allow water flow.

 

[haulnazz15]

Re: Is it necessary to change impeller in Alpha one drive with closed cooling system

Mercruiser recommends you leave the impeller in the drive, this pushes water through the upper for cooling while on plane.
They do show to cut the hose just in front of the bellhousing to allow water flow.

Good point, I had given thought to the plastic water pump melting. It would be easy enough to just cut the hose at the bell housing and plug one end while directing the drive-end downward to dump the water.

 

[Don S]

Re: Is it necessary to change impeller in Alpha one drive with closed cooling system

 

[capecodder116]

Re: Is it necessary to change impeller in Alpha one drive with closed cooling system

Got it...so if it's recommended to leave the impeller in, then it should be renewed on a regular maintainence schedule..?