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24-12-2016, 07:51
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#1
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Registered User
Join Date: Jul 2011
Location: Gulfport, MS
Boat: 1979 Morgan 461, 46' sloop
Posts: 86
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Water in oil, Northern Lights M643 generator
Two questions on a Northern Lights generator. Model No. M643 (TFII18B) 5kw, 1625 hours. I searched the forums and the internet before posting but did not find anything on point.
I had a survey done on a boat I'm considering, including taking oil samples from the engine, transmission, and generator. The generator oil sample result came back as follows:
Overall Alert Level: Action required
Interpretation Text:1ST SAMPLE, SODIUM APPEARS ELEVATED. DETECTED POSITIVE WATER AS WELL. TEST FOR GLYCOL WAS NEGATIVE. INSPECT SYSTEM FOR LEAKS, REPAIR SOURCE. AFTERWARDS; CHANGE OIL AND PULL ANOTHER SAMPLE TO CHECK FOR CONTINUED WATER IN SYSTEM.
With water in the oil, and sodium elevated, but no glycol detected, my guess is that there is a leak / faulty gasket or seal somewhere in the raw water side. I found an operator's manual and parts manual online, but nothing is jumping out at me immediately as the likely culprit. I'd welcome any thoughts or insights from anyone on the likely cause and how extensive the repair might be.
In addition, the surveyor found that when the boat is connected to shore power, the outlets all test correctly as grounded, but with the generator running, the outlets all test as open, not grounded. I don't see anything in the generator manuals about a transfer switch. Any thoughts would be welcome.
Thanks very much.
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24-12-2016, 08:23
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#2
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Moderator Emeritus

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,348
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Re: Water in oil, Northern Lights M643 generator
Being a fresh water cooled engine, the only place salt water can get in that I can think of is the exhaust?
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24-12-2016, 09:39
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#3
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Registered User
Join Date: Sep 2009
Location: Houston
Boat: ‘01 Catana 401
Posts: 9,627
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Re: Water in oil, Northern Lights M643 generator
Quote:
Originally Posted by a64pilot
Being a fresh water cooled engine, the only place salt water can get in that I can think of is the exhaust?
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Either the exhaust or the shaft of the seawater pump.
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24-12-2016, 10:11
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#4
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Registered User
Join Date: Jan 2005
Location: On board
Boat: Van de Stadt 50'
Posts: 1,413
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Re: Water in oil, Northern Lights M643 generator
My money is on the shaft of the Saltwater pump.
Take a green wire from the body of the gen to the ground in your AC system, then test again.
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24-12-2016, 12:21
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#5
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Registered User
Join Date: May 2011
Location: San Diego CA
Boat: Liberty 458
Posts: 2,206
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Re: Water in oil, Northern Lights M643 generator
If the readings are minor change the oil and monitor. If there is water getting in the oil it will become obvious by inspection.
Maybe the PO used a wet funnel to add oil in the past. Maybe the sample was in a tainted container. Stranger things have happened.
Oil analysis is useful data but a single data point needs to be validated.
A single oil analysis is much less useful than multiple analyses. You can detect bearing wear, oil over temp and oil degradation over time.
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24-12-2016, 17:54
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#6
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Registered User
Join Date: Dec 2016
Posts: 24
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Re: Water in oil, Northern Lights M643 generator
Water pump, over cranking filling exhaust, or failed oil cooler could all be culprits.
B
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24-12-2016, 20:01
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#7
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Registered User
Join Date: Aug 2015
Posts: 474
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Re: Water in oil, Northern Lights M643 generator
Bad ground is most likely because the white (neutral) was not bonded to the generator casing and green wire at the generator wiring junction box.
Water in the oil is either coming back from the exhaust (failed anti siphon valve, over cranking or poorly designed exhaust system) or the raw water pump seals. The latter is extremely unlikely as the weep hole usually lets the water leak out before it can bypass two sets if seals and work it's easy into the sump.
Power or sail boat?
Does the exhaust exit the hull sides or transom?
Is there a vented loop installed up high above waterline?
Is there sufficient vertical rise in the exhaust hose?
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24-12-2016, 23:27
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#8
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Registered User

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 8,462
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Re: Water in oil, Northern Lights M643 generator
Water in oil could also be from a leaking oil cooler if this unit has one.
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25-12-2016, 06:19
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#9
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Registered User
Join Date: Aug 2015
Posts: 474
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Re: Water in oil, Northern Lights M643 generator
Quote:
Originally Posted by DeepFrz
Water in oil could also be from a leaking oil cooler if this unit has one.
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True, but I doubt a genset that small would have one.
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25-12-2016, 11:06
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#10
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Registered User
Join Date: Jul 2016
Posts: 247
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Re: Water in oil, Northern Lights M643 generator
the source might much simpler.. improper starting procedure.. I have this generator in my boat..when we bought our boat the generator was frozen..good news..its easy to get parts.. what happens is this. the generator was cranked for 5-10 seconds without starting..this leaves too much raw water in the exhaust..this then leaks into the cylinders...and then the oil.. from what I've found the proper way to start this engine... 1. press the bypass/glow plug switch..10-15 seconds. 2. crank..for no more than 5 sec..if it start all is good..if it doesn't start..this is the part most don't do..close the raw water input, before continuing to crack the engine..once it starts open the raw water valve..the other option is to remove the raw water impeller... -dkenny
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25-12-2016, 11:19
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#11
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Registered User
Join Date: Aug 2015
Posts: 474
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Re: Water in oil, Northern Lights M643 generator
Max duration for cranking really depends on the capacity of the muffler pot.
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25-12-2016, 11:25
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#12
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Registered User
Join Date: May 2012
Location: Western Wisconsin
Boat: O’Day Daysailer II, 17'
Posts: 574
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Re: Water in oil, Northern Lights M643 generator
Could have a fuel cap that leaks seawater which then gets past rings? Sodium appears elevated so maybe not much sodium? About generator ground, the generator is supposed to be isolated from shore power including ground. See https://www.paneltronics.com/atimo_s...11Excerpts.pdf
11.5.5.2.3
The generator neutral shall be grounded at the generator. (See DIAGRAM 2 or DIAGRAM 4.)
11.5.5.6.1
Transfer of Power
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The transfer of power to a circuit from one source to another shall be made by a means that opens all current
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carrying conductors, including neutrals, before closing the alternate source circuit, to maintain isolation of power sources.
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30-12-2016, 18:22
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#13
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Registered User
Join Date: Oct 2009
Location: Redondo Beach, CA
Boat: 1990 Oyster 55
Posts: 468
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Re: Water in oil, Northern Lights M643 generator
Mine too, if raw water pump is gear driven then a small leak of the raw water pump will get a small amount by the oil seal and show up in oil analysis, check the weep hole on the water pump for salt or water
Sent from my SM-G935V using Cruisers Sailing Forum mobile app
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30-12-2016, 18:25
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#14
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Registered User
Join Date: Oct 2009
Location: Redondo Beach, CA
Boat: 1990 Oyster 55
Posts: 468
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Re: Water in oil, Northern Lights M643 generator
I often see sodium increase without measurable water as an early indication on raw water pump seals
Sent from my SM-G935V using Cruisers Sailing Forum mobile app
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30-12-2016, 18:33
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#15
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Moderator Emeritus

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,348
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Re: Water in oil, Northern Lights M643 generator
To get water in the oil from any sea water pump I have seen would mean that both the seal on the water side, and the oil side were bad, and the sea water would have to somehow jump the gap between the two, without draining out the weep hole meant to drain water in the event of a failed seal?
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