Another Flush question?

mnm99

Well-Known Member
Oct 2, 2015
2,445
Long Island
Boat Info
2004 340 SeaRay Sundancer
Engines
Twin 8.1 Merc
If one of these (pic) were installed WITHOUT closing the valve to the raw water, how much raw water do you think would enter the suction if the hose pressure is on? I'm trying to figure out a way to install a flush similar to the Perko valve. What I'm planning do is use a Saltaway mixer along with the hose flush. http://www.saltawayproducts.com/MixerPage.htm The mixer works very well. My problem is I don't want to open the engine hatch every time and shut the valve. I'd like to install a bronze tee and run 2 hoses ( reinforced ) to the locker or something. Just hook up the hose , turn on the mixer and call it done. With the motor running and the hose on I don't think the water would be pushed out the seacock. What do you think?
 

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A diagram would be Helpful. It sounds like you are going to install this unit In the bilge below the waterline. Then run the hose up to the locker and leave the sea cock and the units valves open. If this is the case you are still going to pump salt water into the system along with some fresh water. You will also suck air into the system underway.
 
I'll draw a little diagram later. I know there will be salt water pulling in, but just how much is the question. My friend gave me an idea. I have a few salt water tanks and told me to use a hydrometer and measure the salinity content. This should be interesting. I'm going to samples from the exhaust as is. Then with the T and seacock open. Then T with seacock and saltaway. I don't know if the saltaway will screw it up, but if there is a decent amount in my test can , I know it's in the motor. I know that stuff works form my other experiments. As for air...It will be capped off so no air will be sucked in.
 
Are you not happy with the saltaway injection system you designed - if not what was the problem that leads you to a semi freshawater flush setup.

IIRC Britlady on this forum had some sort of freshwater flush system that was accessable via the locker - perhaps PM her for details.
 
Are you not happy with the saltaway injection system you designed - if not what was the problem that leads you to a semi freshawater flush setup.

IIRC Britlady on this forum had some sort of freshwater flush system that was accessable via the locker - perhaps PM her for details.
I'm happy with my setup, but would really like to get as much salt water out as I can. If I can flush it with the hose while using the saltaway mixer that would be even better. Thats all.
 
So in Theory with this setup and the valve open I should be able to turn on the water and not worry about the engine flooding. Any pressure will run out the pickup before the engine is started. This gives me time to turn on the water walking to the helm. This has been done before, just haven't seen how much fresh water really runs in when the seacock is open along with the pressure of fresh water. That's what the Hydrometer will tell me. Adding the saltaway mixer with the fresh water will neutralize and salt that does come in. I know if I open the strainer cover with the valve open no water comes in because it's higher than the water level also.
pickup.png
 
If one of these (pic) were installed WITHOUT closing the valve to the raw water, how much raw water do you think would enter the suction if the hose pressure is on? ?

Couldn't you detach your intake hose from the strainer and stick it in a 5 gal bucket of water and time how long to suck it dry, then run your garden hose into the empty bucket for that amount of time and the difference will give you a ratio of how much saltwater will be sucked in?
 
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Couldn't you detach your intake hose from the strainer and stick it in a 5 gal bucket of water and time how long to suck it dry, then run your garden hose into the empty bucket for that amount of time and the difference will give you a ratio of how much saltwater will be sucked in?

I could I guess, but that wouldn't really tell me how much is salty and how much is fresh. I know if I put the hose in the strainer at idle the level stays steady in one place at full. I imagine the seawater pickup would be the same at idle. If the seawater was more the fresh water wouldn't keep up.
What I did today was interesting..I went out and bought a hydrometer. Upon testing this is what I found.
--Running the engine direct off pickup my reading was right at 34 ppt out of exhaust.
--Running the engine with fresh water in strainer I was at 0 ppt within 4 min. That's telling me the engine has full fresh water in it.
I want to install a T and see what my results are, but can't find one local that will work. I have to rig something up temp, because the boat is coming out next week...
 
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