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Old 24-12-2015, 12:33   #16
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Re: Intake water Problem

Thanks for the feedback so far. The engine installation was done at the Outremer factory. I would suggest that the basket is installed above the WL for service reasons. I was planning to lower it until it was partly filled even with to lid off. The idea behind the vented loop came from the local yanmar dealer who remarked on the possibility of siphon while sailing. Which may be more of a monohull issue
Why would a vented loop add air to the system, would the pressure of the water keep the valve closed

The more I think and read it sounds like the cup strainer is the issue.
BTW I have never owned diesel engines before
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Old 24-12-2015, 12:49   #17
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Re: Intake water Problem

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..I would suggest that the basket is installed above the WL for service reasons...
If the strainers are plastic, they are probably not certified for use below waterline. Servicing a strainer is a simple matter of closing the sea cock, first, then opening the strainer.
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Old 24-12-2015, 12:54   #18
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Re: Intake water Problem

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If the strainers are plastic, they are probably not certified for use below waterline. Servicing a strainer is a simple matter of closing the sea cock, first, then opening the strainer.
That makes sense
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Old 04-01-2016, 08:10   #19
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Re: Intake water Problem

I am going to remove the screens on the intake ,and see how that goes.
Someone made a comment stating that a vented loop after the the vetus strainer would cause aeration of the cooling water going to the engine.Since the loop is on the pressure side of the pump why would this happen.
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Old 04-01-2016, 11:02   #20
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Re: Intake water Problem

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I am going to remove the screens on the intake ,and see how that goes.

Someone made a comment stating that a vented loop after the the vetus strainer would cause aeration of the cooling water going to the engine.Since the loop is on the pressure side of the pump why would this happen.

That was me.....

You didn't say after the pump, only after the strainer. Either way this won't help with water being drawn out of the strainer. It may even make it happen sooner.


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Old 04-01-2016, 12:08   #21
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Re: Intake water Problem

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That was me.....

You didn't say after the pump, only after the strainer. Either way this won't help with water being drawn out of the strainer. It may even make it happen sooner.


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Sail Monkey thankyou for taking the time and a happy new year to you.
This all new to me but I may be catching on. the scoop strainer will be gone.
After the intake comes the pump then the vetus strainer and then on to the engine and out thru the exhaust. The vented loop was suggested by a yanmar dealer and would have been installed between the strainer and the engine ,it was to stop a possible siphon being created and flooding the block . this has not happened since the boat was launched(2003) so I am not sure why that would change but that is what he suggested .
The more I think of it the more I beleive the scoop on the inlet is the issue

I should know in two weeks
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Old 04-01-2016, 12:31   #22
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Intake water Problem

Are you sure it's thruhull, pump, strainer, engine? That would be odd to say the least.

Usually the strainer is on the suction side of the pump. As well as the vented loop being after the heat exchanger and before the mixing elbow.

If your pump is in fact before the strainer, you may need to replumb things so the pump pulls only clear water.

It may also be a French thing to put the vetus strainer downstream of the pump to catch impeller bits, but then you have a scoop strainer outside the boat that can only be cleared by diving......


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Old 04-01-2016, 13:14   #23
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Re: Intake water Problem

Yeah, it should go through the sea strainer, then the pump, then the vented loop. You can add another strainer downstream of the pump, if you wish, to capture neglected impeller parts.
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Old 04-01-2016, 14:51   #24
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Re: Intake water Problem

I really cant say, I will check when I get there next week. Your absolutely right the strainer should protect the pump. If it was installed the correctly( your sequence) that would explain why it would not self prime. Thanks for helping me noodle through this ,hope its not to frustrating
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Old 04-01-2016, 16:48   #25
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Re: Intake water Problem

The simple solution to this is to move the strainer below water line and in a steady rise to the pump if possible without adding any complication to the system. I have made the mistake of moving mine to an easier to get to location which only caused an air lock when offshore in rough conditions
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Old 04-01-2016, 17:17   #26
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Re: Intake water Problem

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The simple solution to this is to move the strainer below water line and in a steady rise to the pump if possible without adding any complication to the system. I have made the mistake of moving mine to an easier to get to location which only caused an air lock when offshore in rough conditions
That sounds just like my issue. I assume that you reverted to old locations
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Old 13-01-2016, 15:45   #27
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Re: Intake water Problem

Do I understand correctly there is no vented loop currently? Does the strainer basket lid fit and seal properly (greased o-rings)? Is the air coming from the exhaust elbow or somewhere else in the system?
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Old 14-01-2016, 01:01   #28
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Re: Intake water Problem

I'm an old guy and things change, but I have never seen a vented loop on a cooling pump strainer. Usually just on drains and bilge pumps.
I have 4 strainers. All have their tops are above the waterline for ease of cleaning. Also, the valves are a long way from the strainers. My current impellers are 4 years old. One is 10 years old.
When your impeller is new, it probably creates enough suction to overpower the vented loop. As it ages it becomes harder to to draw water because the rubber has hardened and doesn't seal as well. Or it may have gotten hot. Like running with no water.
I think your hull intake strainer is ok.
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Old 26-04-2016, 16:16   #29
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Re: Intake water Problem

Just a note to those that responded to my question. I decided to cut the rubber intake scoop cover on such away that it no longer could create a vacuum or pressure . this eliminated the problem entirely . Thank you for your help. now it is onto fixing the fridge moving the freezer ,fixing the water heater .replacing bilge pump switches and re routing the second reef .
and people think I dont work
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