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Old 09-16-2018, 07:01 PM   #19
DavidM
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City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,785
Dave:

This is how I do it single handed:

Start the engine with the hose connected to the flush fitting with the water valve on and the seacock open. Close the sea cock. The hose collapses a bit as the raw water pump pulls more than the hose can supply, but plenty enough to keep the engine cool at idle. Run the engine for 5 minutes. Close the hose water valve and immediately shut down the engine. Open the seacock.

This flushes the engine and never puts excessive water pressure on the raw water pump. The 10-20 seconds that it takes me to close the engine room hatch (I need to close it to get to the helm) and shut down the engine doesn't hurt a thing.

In my case the engine can pull something like twice the volume of water as the hose can supply. So if you left the seacock open and tried to flush it that way, it would get a mixture of 50/50 sea and fresh water. Not so good. This way you get 100% fresh water and after 5 minutes all of he sea water has been displaced from the engine. I have tested this by pulling zincs at various places along the water path and all tasted fresh.

I have even flushed at a mooring with no dock water available by using the potable water system. The potable water pump puts out even less water so I run it a bit longer, maybe ten minutes to displace all of the sea water.

David
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