# Generator natural gas conversion long term reliability?



## ajnuzzi (12 mo ago)

I just recently converted my durostar ds12000eh dual fuel generator to tri fuel and run on natural gas. It fires right up cold on natural gas and I'm very happy with how it came out besides having to cut my air box (rather than cut the frame). My question is for anyone who has had a natural gas conversion set up for a few years. I'm used dealing with gasoline in small engines and have a good feel for how long stabilized gas can set, how often to run it, winterizing, etc. My concern is if my generator sits for 6 months is there going to be an issue firing back up on natural gas? I doubt it will that long unused anyway, I typically fire it up at least every other month but if it were to sit with no fuel in it or in the carb would I see an issue starting it up again? Once again more curious about this regarding the natural gas, I am wondering if over time if the regulator will need to be retuned etc.


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## Browse Deweb (Jan 16, 2021)

I don't think there is any concern with natural gas not being used regularly, assuming your regulator has a primer on it.


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## OrlyP (Oct 19, 2021)

That's a good question. I myself converted a gasoline-only genny for LP use to get away from maintaining gasoline for long-term storage.

I have went from running the genny on LP every other week down to every month. I will try to get it further down to every other month and maybe settle on a quarterly exercise.

I guess the regular exercise gives you a chance to test the generator and ensure that it will work in an actual emergency, rather than finding out a critter has made a mess of your wiring 6 months ago and the genny has gone faulty when you actually need it. I imagine, this also keeps the parts lubricated (especially on splash oil systems). Running the engine too far apart will give the oil a greater chance to drip out of the parts where they're needed and settle down on the sump.


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## Jackruf (Nov 4, 2012)

ajnuzzi said:


> I just recently converted my durostar ds12000eh dual fuel generator to tri fuel and run on natural gas. It fires right up cold on natural gas and I'm very happy with how it came out besides having to cut my air box (rather than cut the frame). My question is for anyone who has had a natural gas conversion set up for a few years. I'm used dealing with gasoline in small engines and have a good feel for how long stabilized gas can set, how often to run it, winterizing, etc. My concern is if my generator sits for 6 months is there going to be an issue firing back up on natural gas? I doubt it will that long unused anyway, I typically fire it up at least every other month but if it were to sit with no fuel in it or in the carb would I see an issue starting it up again? Once again more curious about this regarding the natural gas, I am wondering if over time if the regulator will need to be retuned etc.


I have used the US Carb conversion kits for over 20 years. First with an open frame Generac, and currently with an EU6500i - The EU6500i was broken in with gas. Since then, exclusively NG. Never a problem letting them sit for long periods. I try to exercise it every other month, but have gone as much as 3-4 months in between. I hold the primer in until I smell gas - then it starts right up. Ethanol gas is the bane of small engines. I avoid it like the plague.


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## 50ShadesOfDirt (Oct 23, 2021)

+1 to the "weekly/monthly exercise" routine. Generac built it in to their line of standby generators, running on either NG/propane. I'd shoot for a similar routine for your genny.

Perhaps Generac's documentation could better explain why it's a good thing ...


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## drmerdp (Apr 10, 2018)

ajnuzzi said:


> My concern is if my generator sits for 6 months is there going to be an issue firing back up on natural gas?


My old champion 7000watt generator has been running NG now propane for over a decade. Has a little over a hundred hours on it. No concern with fuel letting the machine sit for a few months at a time. Id say the primary reason to run the generator from time to time is to heat the oil to remove any condensation that may have accumulated and to make sure the alternator doesn’t loose its residual magnetism.


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## iowagold (Jan 22, 2020)

ajnuzzi said:


> I just recently converted my durostar ds12000eh dual fuel generator to tri fuel and run on natural gas. It fires right up cold on natural gas and I'm very happy with how it came out besides having to cut my air box (rather than cut the frame). My question is for anyone who has had a natural gas conversion set up for a few years. I'm used dealing with gasoline in small engines and have a good feel for how long stabilized gas can set, how often to run it, winterizing, etc. My concern is if my generator sits for 6 months is there going to be an issue firing back up on natural gas? I doubt it will that long unused anyway, I typically fire it up at least every other month but if it were to sit with no fuel in it or in the carb would I see an issue starting it up again? Once again more curious about this regarding the natural gas, I am wondering if over time if the regulator will need to be retuned etc.


make sure to inspect hoses when over 3 years old.
replace any cracked hoses ASAP!
also the make exhaust plugs for when storage in areas where you might have bugs critters etc that light want to move in to the exhaust.
or add on a punch plate screen cone to the exhaust system to help with that.
pm if you need links for those.

make sure to seal up any air gaps in that mod air box.

on to the gasoline part.
best to drain the whole system when storage over 6 months is expected...
i use a double dose of stabil and some sea foam in the gasoline.
pm if you need links for those items.
and avoid ethanol fuel in gen sets. E-0 id the best fuel for when on gasoline or no ethanol.

long term 10 years plus
look at rebuilding the demand regulators as they have a diaphragm that will get hard in over 10 years and affect the fuel flow.
easy to rebuild these and the kits are low cost on the name branded KN or century regulators.
also inspect pipes and fittings.
make sure the black pipe is primed and painted for damp or wet locations.
it will rust over time with the acid rain we have for sure.
if it is installed right you can get 100 years plus out of black pipe.


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## ajnuzzi (12 mo ago)

iowagold said:


> make sure to inspect hoses when over 3 years old.
> replace any cracked hoses ASAP!
> also the make exhaust plugs for when storage in areas where you might have bugs critters etc that light want to move in to the exhaust.
> or add on a punch plate screen cone to the exhaust system to help with that.
> ...


what are you using to plug up any openings such as the regulator intake


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## drmerdp (Apr 10, 2018)

Dust caps. They usually come with the quick disconnects.


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## iowagold (Jan 22, 2020)

mb sturgis has the best soft silicone caps and plugs in the blue color.
avoid the cheap hard yellow plugs and caps off amazon..
they will last a life time!
and for clean up use green can brake clean to make them look like new!


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## ajnuzzi (12 mo ago)

iowagold said:


> mb sturgis has the best soft silicone caps and plugs in the blue color.
> avoid the cheap hard yellow plugs and caps off amazon..
> they will last a life time!
> and for clean up use green can brake clean to make them look like new!


link?


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## exmar (Jun 29, 2015)

All good info. For me, the reason for periodically running and visual inspection is to verify that all is well-when the sun is shining, power is on, not raining/snowing. If I have to deal with something prefer not to if it's cold, dark, etc.


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## somedumbguy (Sep 17, 2020)

drmerdp said:


> My old champion 7000watt generator has been running NG now propane for over a decade. Has a little over a hundred hours on it. No concern with fuel letting the machine sit for a few months at a time. Id say the primary reason to run the generator from time to time is to heat the oil to remove any condensation that may have accumulated and to *make sure the alternator doesn’t loose its residual magnetism.*


Residual magnetism?! I thought you were making that up to have some fun! But the "internet says":
_"Does a generator lose its residual magnetism?_​_When the residual magnetism is lost, the generator will *produce no power at start-up*. This residual magnetism can be lost naturally from not being used or from the load on your generator being connected when the generator is shut off. It can also happen from running a generator with no load for too long."_​I still don't understand what it is but I guess it's a real thing! I wonder how long it takes to lose the residual magnetism by running the generator with no load. I used to do that to burn up gas that was getting old rather than try to dispose of it "properly". If the residual magnetism is lost, is it restored by running the generator with a load?


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## OrlyP (Oct 19, 2021)

somedumbguy said:


> Residual magnetism?! I thought you were making that up to have some fun! But the "internet says":
> _"Does a generator lose its residual magnetism?_​_When the residual magnetism is lost, the generator will *produce no power at start-up*. This residual magnetism can be lost naturally from not being used or from the load on your generator being connected when the generator is shut off. It can also happen from running a generator with no load for too long."_​I still don't understand what it is but I guess it's a real thing! I wonder how long it takes to lose the residual magnetism by running the generator with no load. I used to do that to burn up gas that was getting old rather than try to dispose of it "properly". If the residual magnetism is lost, is it restored by running the generator with a load?


It's a thing.

Think of it as the snowballl effect.

When the generator is at rest, there's obviously no current flowing over any windings. The generator is self-exciting, in that, when you start it, a tiny residual magnetism is needed to create the initial magnetic field to excite the DPE windings. The DPE output is rectified and fed back into the field winding (rotor) through the brushes. The current from the DPE reinforces the residual magnetic field which eventually becomes strong enough to fully excite the stator windings.... which is where your 120V / 240V loads are connected.

When the generator is shut off, some of the residual magnetism remains on the rotor, ready for the next time you start it. However, eventually, it dies out over time due to a number of factors. To mitigate this loss of residual magnetism, many rotors have permanent magnets embedded in them.

Without the residual magnetism, the generator will simply not produce power. To restore residual magnetism, people use a method called "flashing". This involves plugging in a drill or grinder into the generator and giving the drill chuck or grinder disk a brisk turn in the opposite direction.... while the generator is running. This is dangerous, but it's usually the quickest way to jump-start the field.


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## iowagold (Jan 22, 2020)

and some gens heads are having more issues with this.
the perm magnets on the inverter gens do not have this issue.
but you have to watch to make sure the magnets stay glued to the rotor.
rare problem..
but heat is an issue on this.


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## sdowney717 (12 mo ago)

I have gone couple years between runs on both gens. But thet always have produced power, Generac and Troy-Bilt are around 20 years old or older. Do either have those permanent magnets embedded in them?

Now on my Onan marine 1800 rpm gens, I have 2 MCCK from the late 60's, will never have a residual magnetism problem, notice the large field coils.
This one was given to me, and I took it all the way down, and then got it working, but it is missing its marine heat exchanger.

That is a solid steel cylinder. I could barely lift it.









And look at the the huge rotor.









Twin cylinder gas engine

















ONAN MCCK-free September 17, 2015


104 new items added to shared album




photos.app.goo.gl





Over decades, I have had a lot of experience working on old stuff, old boats, electronics, old engines, new engines.

I have also had to repair things where parts no longer are available, but other parts are available that will work ok, if you know what I mean, like rebuilding old Onan water pumps
Onan raw water pump MCCK, 1310165, seal number 1310157

And this is a waterlift muffler, it makes gens super quiet on boats.








Onan water lift muffler


8 new items added to shared album




photos.app.goo.gl













It is steel shell but has a 'roto molded' plastic liner, that is how it survived hot salt water since the 1960's sitting in the bilge of the boat aft lazarette.


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## Columbotrek (11 mo ago)

OrlyP said:


> It's a thing.
> 
> Think of it as the snowballl effect.
> 
> ...


I figured from my auto shop days, that the start battery supplied the current to the alternator rotor winding which gets it started converting the engine mechanical energy into electric energy. Your description makes sense for a non electric start style though. Thanks.


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## Columbotrek (11 mo ago)

On running an engine on Natural Gas. I held a piston which was from the engine of an oilfield jack pump. The story was that it had run on natural gas for 18 years. There was a straw yellow petinia on the dome. No trace of carbon. I bet the head and valves on that engine looked the same. I wonder if that speaks to the engine wear characteristics of using natural gas to fuel an engine.


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## sdowney717 (12 mo ago)

Columbotrek said:


> On running an engine on Natural Gas. I held a piston which was from the engine of an oilfield jack pump. The story was that it had run on natural gas for 18 years. There was a straw yellow petinia on the dome. No trace of carbon. I bet the head and valves on that engine looked the same. I wonder if that speaks to the engine wear characteristics of using natural gas to fuel an engine.


I am certain NGas keeps the engine much cleaner, as it burns a lot cleaner.


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## OrlyP (Oct 19, 2021)

sdowney717 said:


> I am certain NGas keeps the engine much cleaner, as it burns a lot cleaner.


Although, gaseous fuels tend to burn hotter than gasoline. I think the exhaust valve takes the brunt of it and seems to relatively require more frequent lash adjustments. It's a small price to pay, however, and is only a real problem if you get the A/F mix ratio terribly wrong.


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