Sea Pump or Alpha drive impeller pump

[Thayer]

I have a 1999 Crownline LPX that had a 5.7 with with a two-barrell carb. I replaced it with a 350 Mag MPI out of a 2002 Crownline. The new motor has a sea pump on it and I still have the Alpha outdrive. Can I run the two pumps in series? Can I put an idler pulley in place of the sea pump and just use the outdrive pump? (Will that be enough for the mag?) Should I block off the outdrive pump and put in a hull through pick-up for the sea pump? Or lastly, should I put in a Y between the outdrive hose, hull through pick-up hose, and the hose to the sea pump? Any help would be greatly appreciated.

 

[JustJason]

Re: Sea Pump or Alpha drive impeller pump

Any idea what cooling system you have? Raw water or Fresh water? Single point drain, 3, 5 point drain???
Post a few pics of your new setup.

Welcome aboard to iboats

 

[Fishermark]

Re: Sea Pump or Alpha drive impeller pump

Welcome aboard!

I went through the same thing with my boat a few years ago. I asked Mercruiser directly at the time. They recommended leaving the pump in the outdrive, but to cut the hose between the outdrive and the transom. You can just let it splash out against the transom.

Go ahead and put a through hull fitting and sea **** in the hull. The engine mounted pump pumps a greater volume of water and will cool the engine more effectively.

By the way - instead of simply cutting the hose, I went ahead and simply cut the hose inside the engine compartment and routed the water back out the transom with a fitting. My thought was to eventually put a y valve there so I could have a built in wash down pump. But never did do it. It's still a good idea.

 

[Fishermark]

Re: Sea Pump or Alpha drive impeller pump

Here's a pic of my setup. I also installed a sea strainer for easy flushing. (Not to mention the sea weed, etc that the strainer is designed to catch).

If you do decide to go this route, remember that you need to use muffs AND something for the engine mounted pump. As you see, I simply unscrewed the top of the strainer and stuck a hose in it when flushing.

 

[Thayer]

Re: Sea Pump or Alpha drive impeller pump

It is a raw water system and I'm not sure on the number of drains. Would there be anything wrong with running them in series? I really don't want to put another hole in my boat to capture water. I would think the first would just prime the one on the motor as long as it can keep up. I have a gen II alpha outdrive which has a larger impeller in it. What are your thoughts?

 

[Fishermark]

Re: Sea Pump or Alpha drive impeller pump

What are your thoughts?

Bad idea. I don't see any value in that - and a lot of drawbacks. If yo really don't want to cut a hole, then I would suggest removing the engine mounted pump and simply using the gen II pump.

 

[fossill]

Re: Sea Pump or Alpha drive impeller pump

How about removing the impellor and letting the sea pump suck out of the outdrive?