Engine Flush Question

[sogood]

I have a freshwater tank on my boat, which would hold more water than I would use in a very long time. The water is pumped to the sink via a pressure pump and I was wondering about the possibility of putting a "tee" on this supply and running another supply to flush the engine after ( saltwater) use. Is there a way to tap into my raw water cooled 1990 5.7 Mercruiser? My engine seems to be cooled simply via the leg, drawing water is, as per a conventional outboard. I don't see any heat exchanger or any other such devices. What I'm think of is a sort of "wash down" that can be fed through the engine. Any thought much appreciated.

 

[wahlejim]

You definitely want to feed a saltwater flush through the outdrive as saltwater will corrode those parts as well. The only way I can think to do this with an onboard tank is to rig a garden hose that you can throw over the stern of the boat and hook up to muffs. I would also plan on a 12v water pump to feed the muffs. I don't believe that the impeller in the outdrive will be able to suction enough water from a tank on board.

 

[achris]

IF, and it's a big IF, the onboard tank pump can provide enough flow, then you can do what you are thinking of, but it would require a LOT of plumbing.

You would need to add a few of 1/4 turn valves...
Tee the water inlet hose from the drive pump. 1/4 turn in each tee. One goes to the engine, the other to each exhaust elbow. For the one to the engine a tee from the onboard tank...

So, here's how it would work. Normal operations... Drive pump water to the engine, onboard tank water closed.
Flushing. Close drive pump to engine, open onboard tank to engine, open drive pump to elbows (you still need water in the exhaust path to cool the exhaust gases as they pass through the drive).

That's the easiest way to do what you want, and it's far too open to mistakes. I wouldn't do it...

IF the onboard tank pump has the flow, just dive over the side and put a set of flushers on at the end of each day...

Chris......

 

[sogood]

Thanks for the replies. To wahleijm, I wouldn't be depending on the impeller to suck the water as it would be pumped by the freshwater pump. I never thought of just putting muffs on the leg! DOH!
I have a large swim platform that might give me access to the leg when raised, will look into it.
Thanks again.

 

[poconojoe]

Does anyone drink that water from the onboard tank? Probably not, I guess. But if so, a check valve would be in order so as not to allow tainted water to back flow into the tank.

 

[Bondo]

Ayuh,.... I'm also doubtin' whether a wash-down pump can provide enough water flow, to feed the raw water impeller,..??..??