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Old 01-21-2021, 01:51 PM   #1
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Vented loop on Genset Intake?

Hi all,


I have a question about my Northern Lights Gen Set. Does anyone have an idea why a vented loop would be placed between the raw water pump and the engine?


The PO (or perhaps before him) installed a vented loop between the raw water pump and the engine. I have not seen this application of a vented loop before. Usually they are between the raw water outlet and the exhaust riser to prevent back siphoning from the muffler.

The raw water pump goes through impellers like crazy. I sometimes replace 2 impellers per season. I think the vented loop may be allowing the raw water pump to drain down so it runs dry on start up causing the impellers to burn out.

Any advice would be appreciated.

Thanks,
Jeff
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Old 01-21-2021, 02:04 PM   #2
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According to the Northern Lights IM1000 installation manual a vented loop is required between the pump and the engine if the exhaust mixer is less than 12” above the loaded water line. I have one there myself and have no problem going 2 seasons on one impeller. Having a vented loop should not affect your impeller longevity at all.

Ken
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Old 01-21-2021, 02:07 PM   #3
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From Northern Lights own publication "don't drown me" it appears you have your siphon break in the correct position:

https://www.northern-lights.com/medi...t_drown_me.pdf

Perhaps its time to change the raw water pump housing...
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Old 01-21-2021, 02:24 PM   #4
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This is a great diagram and shows exactly what I have. I guess I need to replace the pump. It is expensive, but worth it.
Thank you.
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Old 01-21-2021, 05:19 PM   #5
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It is a better way of installation. The pump has a clear suction path from intake to pump . Therefore never a run dry issue. When a break is before the pump , it is possible for the pump to suck air if the vent fails.
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Old 01-21-2021, 06:15 PM   #6
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Your pump is probably rebuildable. Give Depco Pump a call, they carry the pumps, all the parts, and also do beautiful rebuilding.

http://online.anyflip.com/ucrc/jfuq/...dex.html#p=131
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