Re: Strainer air lock and MORE

Giovanni TESTA

To all,

my history about. I was fast sailing - 9 knt & more, with 60°70° wind port side – from Port Vila, Vanuatu, to South New Caledonia. At sunset I decided to charge batteries with Onan. After very few minutes it stopped. The impeller cover was very hot. Than I start my Yanmar to use the power alternator. Again the impeller cover was very hot and I switched off the engine.

Without power and engine, and the strainer free, I decided to came back to Vila (90 miles) as the harbour is wide and it is possible to anchor sailing.

On the way back, always fast sailing,  I decided to replace (at midnight) the Onan impeller. Than the Yanmar impeller. You never know. But before restart the two engines I wanted to check cooling system. So with valve strainer opened I saw a little, local temporary, water leakage from engine impeller box opened.

Sailing during that afternoon I noticed wide area of pumice. So again I very well looked inside the strainer. It was free. So I supposed there was other stuff inside the way in at hull level (plastic, gel fish, pumice?)

So I decide a very last attempt: to insert a stick into the strainer with opened valve ! My wife Marina shout me not to do it. But…so, with one hand ready to open/close the valve, I inserted the stick: no water at all, the tube completely free and I felt the stick, out&into running water, strong vibrations with my fingers !!!

So I deduced that we were sailing to fast for our impellers sucking work. I reduced our sails to 5 knt to be safe side. First, I used both heads to fill and to check the strainer. All ok. Than I started the engine…crossing fingers. All ok.

At 4 a.m we returned on the way to New Caledonia.


_now with fast sailing speed, 8-9 knt and over, I always before check the situation  with the 2 heads, to be secure that the strainer is full.

_than I check the temperature of impeller cover with my fingers. For me ALWAYS the best and unique  system to check if the system is working properly (other matter if the way out is logged)

Fair Winds

Giovanni Testa

Sv EUTIKIA SM2K  n 428

Here some video of our sailing around the world.

Il 05/03/2020 23:10, Ryan Meador ha scritto:
We've experienced something like this.  For us, the problem was air leaking into the low pressure (suction) side of the system, not the high pressure side.  The gasket on the raw water strainer was not sealing well.  We fixed it by greasing it well with silicone grease and tightening it down.  Really we probably need to replace the gasket (add it to the todo list).  The problem seems to get worse when the inflow is restricted, so you might want to check the strainer and thru-hull for barnacles and that sort of thing.

I doubt the hose you added to the anti-siphon valve is the cause.  Your description of what you did is almost exactly what the Amel setup is.  If water isn't flowing out, it's probably because water isn't flowing through your engine.

Ryan and Kelly
SM 233 Iteration
Boston, MA, USA

On Tue, Mar 3, 2020 at 7:38 PM Patrick McAneny via Groups.Io <> wrote:
Sailing back from Bermuda last spring , my engine would shut down and I discovered that there was no water in my strainer ,thus the engine had no water and shut down. We were sailing in only moderate to strong conditions ,but never heeled beyond 20 degrees. When I opened the strainer lid water would flow to the top, and I could motor once again. This same thing happened repeatedly ,and had never happened prior to this trip. I made a change to the cooling system in Bermuda, and I want to know if this may have caused this air lock .
Upon starting any boat engine, I have always checked the exhaust for water flow. However on my Amel the exhaust is at water level making it impossible to see if cooling water is flowing. When a couple of owners a while back posted that they had a small hose streaming cooling water into the cockpit confirming flow, I wished I had that set up,Amel must of added this feature to newer models.
So in Bermuda I took off the anti siphon valve off the loop at the top of the hose from the heat exchanger to the exhaust elbow. In place of the valve I ran a small hose to my cockpit scupper to show me water flow. It worked only marginally well ,I surmise most of the water flow never rises to the top of the loop. I figured it still served as a siphon break as it is open to the atmosphere . My question is ,could this have allowed all the water to flow back out of the engine and strainer while heeled over and create an air lock ? Secondly has anyone have a photo of how this system is installed ,I would like to replicate it.
SM Shenanigans

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