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Old 14-09-2016, 05:28   #1
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Strange Generator Problem

My generator (Kohler 6.5EFOZ) shut itself down today, only the second time in almost 2000 hours and 7 years in my ownership.

I opened the sound enclosure to find leaked seawater. Damn.

What is weird is that the exhaust elbow was stone cold, sea water pump cold, operating temperature normal, coolant normal. Oil normal. So why did it shut down?

There are not that many places where sea water can leak from, as on this admirably simple three cylinder Yanmar sea water goes into the sea water pump, from there to the externally mounted copper heat exchanger, and from there to the exhaust elbow.

I found a loose hose clamp on the heat exchanger to exhaust elbow hose. That doesn't seem to have solved the problem, but surely I will find it. Must be in that hose somewhere so I'll just replace it.


But meanwhile -- WHY did the generator shut itself off? As far as I know there are three shutoff systems: 1. high coolant temp; 2. high exhaust temp; 3. low oil pressure. This is breaking my head. Anyone have any clue?
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Old 14-09-2016, 05:34   #2
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Re: Strange Generator Problem

Put salt water in electrical areas and no telling what will happen.
I think you got lucky, mine sprayed salt water all around inside of the sound enclosure until the raw water pump finally seized, that caused an overheat and a shutdown. My source of the leak was the raw water pump, I got rid of it.
You sure it monitors exhaust temp? Just curious. I would think low oil pressure and fresh water temp would be all.

Be really slick if it had a sensor that would shut it down if it got wet though.


On edit, my opinion is a raw water pump in a sound shield is not a good design
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Old 14-09-2016, 05:37   #3
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Re: Strange Generator Problem

Is the elbow in good order? Not blocked and not cracked or corroded through?
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Old 14-09-2016, 06:20   #4
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Re: Strange Generator Problem

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Put salt water in electrical areas and no telling what will happen.
I think you got lucky, mine sprayed salt water all around inside of the sound enclosure until the raw water pump finally seized, that caused an overheat and a shutdown. My source of the leak was the raw water pump, I got rid of it.
You sure it monitors exhaust temp? Just curious. I would think low oil pressure and fresh water temp would be all.

Be really slick if it had a sensor that would shut it down if it got wet though.


On edit, my opinion is a raw water pump in a sound shield is not a good design
I agree with you about raw water pumps inside sound shields. I will really think about this when I build the next boat. Your experience sounds like a total nightmare.


Yes -- my generator monitors exhaust temp, coolant temp, and oil pressure. I don't think it has any sensor for getting wet; at least, there's nothing in the manual about it.

I didn't have salt water spraying around anyway, rather dripping into the bottom of the sound enclosure.

Generator seems to be running ok now, but I'm going to replace that hose. Must have a pinhole in it somewhere. Maddening that I can't find the source of the leak.
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Old 14-09-2016, 06:21   #5
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Re: Strange Generator Problem

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Is the elbow in good order? Not blocked and not cracked or corroded through?
It's not cracked or leaking, but I will pull it off and have a look inside. Thanks.
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Old 14-09-2016, 06:25   #6
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Re: Strange Generator Problem

I know of some generators that also monitor water flow. Not sure if yours is one or not.
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Old 14-09-2016, 06:55   #7
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Re: Strange Generator Problem

"I know of some generators that also monitor water flow. Not sure if yours is one or not."

My Northern Lights has such a shut-off. It provides only a light and audible alarm for overheat.

John
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Old 14-09-2016, 07:00   #8
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Re: Strange Generator Problem

Well, I think I found the leak. The hose clamp on the heat exchanger to exhaust elbow hose -- the one I found loose -- was actually corroded and broken on one side. I removed the hose, cut a fresh end, put a new hose clamp on, and it seems not to be leaking any more. Generator running normally (touch wood).

Now I have the fun job of washing everything down to remove traces of sea water.


Still bothers me intensely that I don't know why the automatic shutdown.

Maybe it was a ground fault? But I don't have this either as far as I know -- nothing in the manual about it.

It shut down several times, too. After the initial shutdown, I opened the sound enclosure, poked around everything, measured temperatures, check oil and coolant, and restarted it. It ran for a few minutes then shut down again.

Bizarre.
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Old 14-09-2016, 07:02   #9
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Re: Strange Generator Problem

Concerning A64's point about salt water inside the enclosure --

I think I might get not only the salt water pump, but even the heat exchanger, out of the enclosure.

Or maybe better no enclosure at all. My sound enclosure is not really much needed, as my engine room is well sound proofed. Would sure improve access and reduce operating temperature.
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Old 14-09-2016, 07:51   #10
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Re: Strange Generator Problem

If you have no need of the enclosure, it removes easily doesn't it?
Just take it off and see how much louder the generator is, I believe with mine, it's a necessary evil, and I think if properly designed, the generator will run cooler with an enclosure, cause it will be directing airflow where it's needed.
The only problem with mine is it sucks the hot air from the enclosure, I think that stupid, I think blowing cool air into it would be smarter, surely all that heat has to shorten the blowers life?

Near as I can tell mine wasn't harmed with all that salt, I washed everything down well and have now sprayed the whole thing with Corrosion-X.
I did drill some drain holes in the bottom of the housing as it was like a bathtub without any drain.

In talking with the guy at Nexgen, he keeps stressing the major thing to make one live, is to run it often and let it get hot and dry out, I guess condensation gets a lot of them over time?
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Old 14-09-2016, 08:33   #11
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Re: Strange Generator Problem

Just downloaded and read the troubleshooting section for your generator. Besides the obvious things to check (good fuel flow, oil pressure, coolant levels, etc.), one of the faults listed is faulty or loose wiring harness connectors. Check all of your connectors on the engine wiring harness since saltwater may have intruded into these areas. Also listed as a cause for sudden shutdown is a faulty Exhaust Temp Sensor. Maybe your's is on its way out and wants to work most of the time but does a "hiccup" every now and again. Something to look into. Same could be the case for any of the other sensors. With 2000 hours on the genny, might want to pull the Oil Pressure sensor and make sure that it isn't partially clogged with carbon sludge accumulating between oil changes. If not overly expensive to do so (Oh, it's a Yanmar...sorry, forgot), I would change out all sensors one at a time and see if the problem persists, or you can isolate which circuit is causing the shutdown and then further investigate the cause from there. Hope this helps somewhat Might, might not.....just armchair troubshooting from here. (But downloading and reading "porn for Engineers",...er, tech manuals is fun! Good Luck!
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Old 14-09-2016, 12:11   #12
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Re: Strange Generator Problem

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Originally Posted by Dockhead View Post
But meanwhile -- WHY did the generator shut itself off? As far as I know there are three shutoff systems: 1. high coolant temp; 2. high exhaust temp; 3. low oil pressure. This is breaking my head. Anyone have any clue?
Quote:
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Still bothers me intensely that I don't know why the automatic shutdown.

It shut down several times, too. After the initial shutdown, I opened the sound enclosure, poked around everything, measured temperatures, check oil and coolant, and restarted it. It ran for a few minutes then shut down again.

Can't speak to the water leak, and you've fixed that anyway... but you know we have the same genset in the 60-Hz version. Had two faults with the thing this season, one a MAJOR pain in the a$$.

The big one was that the fuel filter assembly actually broke. The inlet piece is simply press-fit into the top of the filter assembly... and when that sucker pops out -- but not enough to actually cause the motor to stop -- the result is 30-40 gallons of diesel spewed around the engine room and settled in the bilge. That happened when I started it for the first time this season, Spring commissioning. Checked everything after I first started it, went up above to load it and let it run up to operating temps... and sometime after that it all went south. Took me about 3 weeks to clean up everything. IF IF IF the filter assembly inlet port had completely separated from the top of the filter housing... the engine would have stopped. If it has separated enough to suck air, but not enough to be obviously leaking (aka spewing) that might cause the engine to stop. Not sure if this in-between situation can happen, though... but then again, I didn't think the inlet port could just decide to take half of a hike, either.

The second fault... is that the electric fuel pump just went south. Start, run, stop. Repeat. So fuel pumps can worth a look, too.

-Chris
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Old 14-09-2016, 12:25   #13
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Re: Strange Generator Problem

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Originally Posted by ranger42c View Post
Can't speak to the water leak, and you've fixed that anyway... but you know we have the same genset in the 60-Hz version. Had two faults with the thing this season, one a MAJOR pain in the a$$.

The big one was that the fuel filter assembly actually broke. The inlet piece is simply press-fit into the top of the filter assembly... and when that sucker pops out -- but not enough to actually cause the motor to stop -- the result is 30-40 gallons of diesel spewed around the engine room and settled in the bilge. That happened when I started it for the first time this season, Spring commissioning. Checked everything after I first started it, went up above to load it and let it run up to operating temps... and sometime after that it all went south. Took me about 3 weeks to clean up everything. IF IF IF the filter assembly inlet port had completely separated from the top of the filter housing... the engine would have stopped. If it has separated enough to suck air, but not enough to be obviously leaking (aka spewing) that might cause the engine to stop. Not sure if this in-between situation can happen, though... but then again, I didn't think the inlet port could just decide to take half of a hike, either.

The second fault... is that the electric fuel pump just went south. Start, run, stop. Repeat. So fuel pumps can worth a look, too.

-Chris

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Old 14-09-2016, 12:49   #14
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Re: Strange Generator Problem

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That looks concerning.

I'd want it tapped for a threaded connector.
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Old 14-09-2016, 12:52   #15
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Re: Strange Generator Problem

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That looks concerning.

I'd want it tapped for a threaded connector.
Eh, a little gorilla tape and you'll be grand
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