Full internal cooling systems mercruiser 4.3MPI

William gearing

New Member
Jan 3, 2019
2
Nelson New Zealand
Boat Info
Sea ray 280 Sundancer 2007 twin mercruiser 4.3 MPI
Engines
Twin 4.3 mercruiser mpi
Hi all,
I have a 280 sundancer with twin 4.3MPIs. It’s a 2007 boat with lowish hours and I want to put it into the sea. It’s been fresh water all it’s life. I am looking at either an Oem mercruiser full internal cooling system which means two new ecms or the cheaper Monitor. System which looks pretty well built. Does anyone have any advice? On either system and anything else I should do.
Thanks
Will
 
Will
Do you plan to keep the boat in salt water full time or will you be able to remove it when you are not using it?
If you plan to keep it in the water full time, I assume you have V Drives.
I'm sure you will get plenty of comments, but my feeling is that if you can take the boat out of the water when not in use, then fresh water cooling may not be necessary. I am able to keep my 320 in high and dry storage when not in use and my cooling system lasts about 5 or 6 years before I replace Manifolds etc. I do however flush both engines after every use.
Lets see who has varying opinions.
 
Will,

I agree with Gary. If you operate that boat in salt water, you NEED to haul it out and flush it after use. Either on the rack or a lift. Leaving it in the water with any kind of cooling kit will kill it.
Now, as for the cooling kit..... ABSOLUTELY get one! Especially if it's a freshwater boat and has never seen salt. Well worth the effort.
If it has been salt all it's life, I could make an argument to not mess with the cooling system, like mine. However, I'd be surprised if you'd get 5 or 6 years of life from your manifolds....consistently. We change ours every three years, and pull the drives for R&R, impeller every year. And still have a lot of salt water issues. (And it's on a lift).
 
Ok thanks guys appreciate it, i was planning to keep it berthed all the time but will now keep the boat out on a trailer and flush after every use. Will look into cooling kits as well. A silly question, how do i flush the engines, is there a kit needed or is the capability there on a standard MPI installation? I have only ever flushed outboards before.
Thanks
Will
 
To flush the engines you’d use earmuffs connected to a hose on the drives
 
You don’t mention which drives you have.

Alphas have the raw water pump in the outdrive which pushes raw water into the engine. They would need the earmuffs to flush the motors.

A Bravo 3 has the raw water pump mounted to the engine, which draws in raw water. A Mercruiser flush kit is available to flush these while still in the water.
 

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