Generators. The Good, Bad and The Ugly

Codger2 said:

I just bought a boat that came with a 12KW NL generator. I've heard nothing but "good" about these sets......we shall see!

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Congratulations, Walt. Proper yachting attire complete with ascot is in order for commanding that beautiful vessel.

By the way, if the 12KW NL doesn't have a stainless steel exhaust elbow, change it. That's the only problem I heard of with those gens. Mine had to be changed.

Have an Onan 8 or 9 kw Mdak with 3 cyl. Kubota in sound shield. Sound shield is mounted on rails on Sound Down vibration mounts. Exhaust runs through a Gen sep. Salon floor is very well sound insulated, so the air conditioner is louder than the genset. There is no vibration. Love those vibration isolators. Normal maintenance so far for 13 year old generator with 700 hours. Did have to replace gaskets on heat exchanger and raw water pump. Also replaced end bearing in generator when we had it out for boat repower. My one complaint is that for the price of the sound shield you would think they could make the pan stainless or galvanized it. When the end gaskets and the raw water pump leaked, it made a hell of a mess. Sandblasted it, added a drain hole (sits over bildge), faired it, and painted it with Awlgrip (leftover from another job).





Ted

Like Capt. Tom, our Onan MDJE is pretty loud inside the boat but very quiet outside. It has a Vetus wet exhaust muffler on it which isn't very large but seems to do the trick.

We took the generator's sound shield (a stock Onan unit) off awhile back when we had the starter removed and completely rebuilt. Haven't gotten around to putting it back on and it does make a significant difference to the generator noise inside the boat. But not the vibration.

You guys with the MDJ series especially, and other gennies for that matter, can knock a heck of alot of noise down by putting a silencer on the air intake. Amazing how much noise actually comes out the intake. Donaldson makes filter/silencers like those used on bobcats, etc. Remote mount and tie in with pvc pipe and hose sleeves to connect.

JDCAVE said:

Chuckle! Yup! Managed to break the check valve last summer! Managed to put another one on without too much trouble but I spent 4 days in Pender Harbour resolving the problem.

Broken check valve
View attachment 37400
New check valve.
View attachment 37402


Jim
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Just an FYI but I don't believe the March pumps are designed torun upside down like that.

8Kw NL, no sound shield. Not original to the boat. Came with the boat. Sized great for running two 16k BTU AC units and hot water heater. Hope to add an electric stove soon- probably will need to switch something (s) off. Starts/ runs great. No issues except leaking oil seal on raw water pump drive and a failed alternator. About 2000 hours on it- but is 10 years, plus old.


1983 Present 42 Sundeck
Twin Lehman 135's

Capt.Bill11 said:

Just an FYI but I don't believe the March pumps are designed torun upside down like that.

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Yup. March says the pump should be mounted horizontality.

Moonstruck said:

By the way, if the 12KW NL doesn't have a stainless steel exhaust elbow, change it. That's the only problem I heard of with those gens. Mine had to be changed.

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See, now that's the kind of info I need! At my age, there is not enough time left on the water to learn all these things by experiencing them. That's the reason I re-upped here at TF. Thanks, Don!

Cap'n Bill, Larry, thanks, I'll look into that. The PO installed this. I'll check and see if it can be reoriented. For now it works most of the time, but I will see what can be done, because it is a PITA to deal with when it looses it's prime.


Jim
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So I just started the genny to run some heaters. As part of the process now I check the genny exhaust for water and it was running fine. I routinely close the seacock now after every use. The priming issue has become quite intermittent now and I can live with it. Hopefully can get onto it over the next couple of months.


Jim
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I think the reason for mounting that pump horizontal is that it is water cooled with a potted loop of stainless tube- mounted vertical there may be a concern of the cooling loop trapping air and pump getting hot. So check it periodically to see if motor is getting hot.

JDCAVE said:

routinely close the seacock now after every use.

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We do this as well. To ensure we don't accidentally start the generator with the seacock closed we installed a red, spring-loaded switch guard over the generator start switch. The guard represents the seacock. When the guard is closed over the switch, the seacock is closed. When we open the seacock,we open the switch guard.

We have the same arrangement for our big salt water washdown pump which has its own through hull and seacock and on-off switch on the panel.

1977 Kohler 7.5 gasser. Not much noise at all and no vibration. Have no idea how many hrs.; uses no oil and oil stays clear-clean. Understand elect system was redone not too long before we purchased, no paper on it. Can take whatever we give it and idles at low rpm unless much load is applied. In nearly 7 yrs only item I replaced was easy access diaphragm fuel pump (center of pict).

djmarchand said:

Darren:

I too have the 3.5 KW NextGen which runs everything I need to on my boat, just not all at the same time ;-). But its noise is not a benign burble; more like an annoying (to boats anchored behind me) putt, putt. What kind of a muffler do you have?

David

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Hard to see the sides of the muffler, but I believe it's a Centek (a smaller version of the ones on the FL120s). I also have a good rise with about a 15-foot run aft to the exhaust fitting. Don't know if that helps acoustically or not, but with the engine room buttoned up (port lights closed) you can hardly hear the unit running on the outside, just the burble-burble-woosh.

Darren:

I have the same water lift muffler I think, but a much shorter run from it to the transom, probably about 6'. The shorter run makes it drop steeper which may account for the higher nosie. Not enough water/exhaust mixing.

Thanks for your response.

David

Ski in NC said:

I think the reason for mounting that pump horizontal is that it is water cooled with a potted loop of stainless tube- mounted vertical there may be a concern of the cooling loop trapping air and pump getting hot. So check it periodically to see if motor is getting hot.

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The impeller rides on a shaft and I don't believe it is intended to ride down on one end of the shaft like it would if you mount the pump in that manor.

Capt.Bill11 said:

The impeller rides on a shaft and I don't believe it is intended to ride down on one end of the shaft like it would if you mount the pump in that manor.

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Differential pressure on the impeller is way more than the weight, so that is not an issue. Also it is a magnetic drive pump so motor rotor is not in contact with impeller.

Pgitug, now you no longer have a blank page on gensets, any supplementary questions?

Yeah but the impeller floats free on the shaft and I'm not sure the impeller is supposed to ride with its full weight on that little ceramic washer that would end up at the bottom of the shaft if you mounted the pump in that fashion. Especially if the pump is not priming all the time and therefore running dry more often then it normally would be.

But I could be wrong.

Onan Something with 3 cylinders, 7.5 kW. Noisy waterlift exhaust, starts and runs every time, except once the fuel filter had never been changed; pushed up against a bulkhead so servicing the heat exchanger total bitch! When I went to check the strainer, the outlet hose fell off, 3/4" hose on a 1/2" fitting with electrical tape!! What were they thinking? PO was a moron so not the genset's fault.

I have a 30 YO Westerbeke 8 BTD without a sound shield. Running fully loaded is not loud in the cabin. Even in the ER is tolerable short term without ear muffs. It ran perfect during the survey and for the first few hours we owned it. Next trip out the temp climbed right up over 200 while pumping plenty of water and I shut it down. The overflow reservoir level never moved. Line was clogged and the level was low. Installed a new thermostat, cleaned, flushed and refilled and temps are all normal. Next trip out the thrust plate that joins the gen rotor to the flywheel sheared. I shut it down in a few seconds. Mechanics said they never seen one fail like that before. I believe them. Fingers crossed.
Otherwise this is a simple, easy to maintain machine.

We have a marinised Kubota 600cc 3cyl 12hp diesel driving a 24V 150A bus alternator via twin belts, with an Amplepower V3 external regulator. This charges the batteries directly. For AC power, we have two RV inverters - a 2KVA modified sine-wave and a 1.5KVA pure sine wave. The system has never given any real problems since installed 10 years ago but I discovered that without current limiting and at full charge rate, the belts stretch and fail very quickly. So I limit it to about 90 amps.
The stop control also acts as a variable speed control and, with no sound shield, the internal noise can be controlled to suit. Vibration is minimal. With a Vetus water lock muffler and a water separator, it's virtually silent outside. .
Only did this because it was towards the end of the conversion of Pioneer, the budget was blown and I could build it myself...both the Kubota and alternator were non-recon used.

Bendit said:

We have a marinised Kubota 600cc 3cyl 12hp diesel driving a 24V 150A bus alternator via twin belts, with an Amplepower...

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Isn`t Kubota the engine used in many Onans? Maybe not now Cummins owns Onan.

BruceK said:

Isn`t Kubota the engine used in many Onans? Maybe not now Cummins owns Onan.

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Onan still uses Kubota for all their little gennies, up to somewhere around 15-20kW.

Dealt with a few generaters over the years and fitted a new 15kw Phasor 2 years ago in my Cheoy Lee 50 Tri cabin. These are one of the quietest of genny's in fact I did not fit the sound sheild it's so quite. They are powered by Kubota, a heavy diesel. Run at low speed (no screaming demons) These are the quietest Genny's I know of and are incredibly reliable. We can stand alongside it whiule running and have conversation without shouting at stupid levels. The 2 cabins fwd and aft of the engine room, you can engage in conversation at normal levels etc. Very low vibration transmission. Not sure of your timeline but will be back on the boat 1st week of April and could put my decible meter on it.

I have a 5.5kw Northern Lights. It's 15 years old and has ~650 hours.

Pros: Plenty of power, smooth, quiet (especially outside the boat thanks to gensep), starts easily, outstanding factory support

Cons: Raw water pump is currently leaking oil and needs to be replaced, why doesn't NL include the stainless steel exhaust elbow with new units???, sound shield is a bit difficult to remove because of the number of screws involved (solved on newer units), in the summer when I don't want to run electric heat it's difficult to properly load the generator

Overall I'm very happy with the unit. After having a boat with a generator it would be tough to go without.

I just saw an EFOY fuel cell generator. Wow, the genset is dead! Ain't technology wonderful?

Xsbank said:

I just saw an EFOY fuel cell generator. Wow, the genset is dead! Ain't technology wonderful?

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Yup, I could replace my 8KW genset with 80 of those units at a USA cost of $560,000 and an hourly operating cost of $87 for fuel. Why does it not surprise me that the USA retailers are in California, Washington state, and Massachusetts.

Ted

"but I discovered that without current limiting and at full charge rate, the belts stretch and fail very quickly. So I limit it to about 90 amps."

Sounds like an automatic (spring) belt tightener might be on the next NAPA visit wish list.

Cap'n Bill and Larry and all: Thanks for the "Heads up" on the March Pump. It was the PO install. I was willing to live with it unless it caused damage to the pump. So I phoned March's technical people with the particulars and the fellow said that it could cause damage, depending on the duty cycle and water temperature, so I will remount it. It will require jockeying some fittings around, so will see what I can do.

Thanks again! Jim