Exercising Generator November 27, 2018, 05:48:44 pm I'm new to RVs with a generator and and just got home from a special trip to town to exercise it for a couple of hours as per onan recommendations and "common knowledge" that seems to be in agreement that this is necessary. To kill time while doing this I did some research on the subject and found wildly different points of view on this. Many people said they have had their onan generator for many years and never exercised it with no resulting problems while others say every couple of months is more than enough and an hour is plenty if it's under load and the coils get hot enough to dry off. Generac mentions nothing of this in their home based standby generators and I've had a 5000 watt cheapo Home Depot generator for ten years that I only use occasionally for larger tools like my planner that I never exercised beyond occasional starts and short runs so carb didn't glaze up. It has me wondering if this once a month ritual with my onan is really necessary. What am i missing here?
Re: Exercising generater Reply #1 – November 27, 2018, 06:22:46 pm Quote from: Sawyer - November 27, 2018, 05:48:44 pmWhat am i missing here?You are missing a generator that won't start due to a plugged carburetor or won't produce power due to a blown $300 voltage regulator due to resistance between the brushes and slip rings. When you get that you will change your tune. If you don't get it, more power to you.I have a lawn mower that gets used once a year and always starts. I'm not sure why but it has nothing to do with a dead Onan. Those of us that have paid (dearly I might add, I have two Onans) choose to drain the carburetor between runs and do the once a month thing.
Re: Exercising generater Reply #2 – November 28, 2018, 08:54:31 am Quote from: hbn7hj - November 27, 2018, 06:22:46 pmYou are missing a generator that won't start due to a plugged carburetor or won't produce power due to a blown $300 voltage regulator due to resistance between the brushes and slip rings. When you get that you will change your tune. If you don't get it, more power to you.I have a lawn mower that gets used once a year and always starts. I'm not sure why but it has nothing to do with a dead Onan. Those of us that have paid (dearly I might add, I have two Onans) choose to drain the carburetor between runs and do the once a month thing. I'll put you in the generator must be exercised column. I fully agree on the carb issue and I filled up with non ethanol supreme and added Sta-Bil to it to guard against that in generator and coach motor. Kinda spendy but..... A lot of these carb problems in small engines are due to ethanol being added which has been a nice gift to farmers but the rest of us suffer the consequences. 1 Likes
Re: Exercising generater Reply #3 – November 28, 2018, 12:12:44 pm As a retired mechanic and Mechanical Supervisor at LAX, owned by the City of Los Angeles, I have a bit of experience with generators and included periodic running (usually every week) of all building generators. Generators need and love to be periodically run and is manufacturer recommended and sometimes legally required, such as in public buildings . Generators should alway be test run under a heavy load, to warm the generator and motor oil to its normal operating temperature and allowed to stay running for a minimum of a half hour, longer in very cold conditions.It keeps carburetor's fuel bowl full of fresh fuel, eliminating the gumming up the carburetor, as old fuel slowly evaporates. Periodic running keeps the generator's slip rings free of corrosion and the brushes clean, both things that, if dirty, will prevent power from being generated.With the generator being exposed to the elements and the atmosphere, the armature and field windings accumulates moisture that attacks the thin insulation. Running under load heats the windings and boils off any moisture .Several shorted armatures have been reported on this site. A new or rewound armature is very expensive, both to buy and to install. Burning a quart of gasoline, once a month is a cheaper alternative.Periodic running also keep the interior of the engine coated in oil. When an engine sits for long periods, the oil drains from the higher sections into the sump. The metal, in higher parts of the engine, can dry out and begin to rust, not especially good for a cylinder wall and other ferris materials. Running until hot boils off any moisture that has accumulated in the oil, through condensation . This is an even greater concern if the generator is stored in a moist environment, the engine's crankcase is open to the atmosphere.Do you HAVE to run the generator monthly? No, you may get lucky for a while but in the long-term, it is a risky gamble, one that is easy to mitigate the risk of future failure, which usually happens at a bad time. The best maintenance you can give your generator is a monthly run.Larry 12 Likes
Re: Exercising generater Reply #4 – November 28, 2018, 02:33:06 pm "The best maintenance you can give your generator is a monthly run."LarryThat brought back memories of when I was assigned to a remote communications site with the Air Force. Although I had nothing to do with 'Power Production' I did mingle with that crew on nearly a daily basis. There were four (4) humongous generators on site. Only one of those was on line at any given time but one or more of the others were always being run as a mater of routine maintenance. On weekends it was a blessing to have only the primary on line, sounds of silence.
Re: Exercising generater Reply #5 – November 29, 2018, 07:45:17 pm The best combination of methods seems to be to let the unit warm up for 5 minutes then add the "load" for 20 minutes; then 5 minutes without load to cool down. Do at least once monthly.Special consideration should be given to the oil dip gauge. Never over fill otherwise the unit will not run properly. 1 Likes
Re: Exercising generater Reply #6 – November 29, 2018, 11:51:00 pm Quote from: hbn7hj - November 27, 2018, 06:22:46 pmYou are missing a generator that won't start due to a plugged carburetor or won't produce power due to a blown $300 voltage regulator due to resistance between the brushes and slip rings. When you get that you will change your tune. If you don't get it, more power to you.I have a lawn mower that gets used once a year and always starts. I'm not sure why but it has nothing to do with a dead Onan. Those of us that have paid (dearly I might add, I have two Onans) choose to drain the carburetor between runs and do the once a month thing. What kind of lawn mower is that? I want one of those, instead of the one we have that gets used weekly in the summertime!Dottie and Ms Liz 2 Likes
Re: Exercising generater Reply #7 – November 30, 2018, 07:58:46 am Quote from: phil5e - November 29, 2018, 07:45:17 pmThe best combination of methods seems to be to let the unit warm up for 5 minutes then add the "load" for 20 minutes; then 5 minutes without load to cool down. Do at least once monthly.Special consideration should be given to the oil dip gauge. Never over fill otherwise the unit will not run properly.I keep hearing two hours but last time I got bored and only ran it an hour under a pretty heavy electric heater load. Seems like enough to me too.
Re: Exercising generater Reply #8 – November 30, 2018, 08:02:03 am Quote from: dtice - November 29, 2018, 11:51:00 pmWhat kind of lawn mower is that? I want one of those, instead of the one we have that gets used weekly in the summertime!Dottie and Ms LizYeah it seems like I live on my Craftsman riding mower in the summer. Like stringing beads with no knot at the end. Then I get about a month off and it's time to fire up the snowblower.
Re: Exercising generater Reply #9 – November 30, 2018, 10:11:26 am Quote from: dtice - November 29, 2018, 11:51:00 pmWhat kind of lawn mower is that? I want one of those, instead of the one we have that gets used weekly in the summertime!The lawn service does it all summer but it seems like there is always one time between green and brown for me to do.
Re: Exercising generater Reply #10 – December 02, 2018, 09:49:38 pm Some very embarrassing moments and $500+ later, I now run the generator on my 2003 LD for at least a half hour every month as indicated in the manual. I put a reminder on my phone calendar so I don't forget. I'm glad to know, from the posts here, that I should run it longer when it's cold outside. The thermometer is reading 16 degrees.The generator ran fine for several hours powering the AC to cool the interior of the LD the 4th of July one year, but the next spring it wouldn't start. I took it to the shop. The repair guy opened it up. The embarrassment came when he got a face and mouth full of mouse parts emitting from the generator when he got it started. Seems the cats who share the garage with the LD had not been doing their job.The necessary repairs were made, I paid the $500+, and went home with a lighter wallet but happy, only to have it stop running again. I took it back in and he found a crack in the fuel line to the generator. The line had deteriorated. He replaced that and the filter while he was under there, but first he came out with his head bleeding. The generator still wouldn't start. He said, "I'm going to ask you what sounds like a stupid question, but how much gas do you have?" It was about a quarter full. I was going to fill up on my way home. "Please go fill it up now," he said. That's when I learned the generator won't leave you high and dry somewhere since it won't run on less than a quarter tank of gas.I learned a lot but it cost me some bucks and a goodly amount of embarrassment. 1 Likes
Re: Exercising generater Reply #11 – December 03, 2018, 10:51:25 am "I learned a lot but it cost me some bucks..."I am sorry for your unneeded expenditures Judy, sometimes education can be expensive.But since you've wisely joined this forum maybe next time you will seek assistance right here first. Welcome to the group! 1 Likes
Re: Exercising generater Reply #12 – December 03, 2018, 11:24:55 am Keep hearing a lot about fuel line deterioration and looking at mine they seem fine but it's hard to tell. One of the things about buying a used LD of my vintage (1997) is that it's a guess as to whether or not certain things have been replaced or not. Stuff like fuel lines could be relatively new or just about to go. Following my if it ain't broke don't fix it philosophy I'll just wait and see I guess.
Re: Exercising generater Reply #13 – December 03, 2018, 01:23:14 pm "Keep hearing a lot about fuel line deterioration..."Yes, it was a common failure for some of us!There are two sections, each approx. 2" long, one at the point where the genny fuel line exits the main tank and another at the genset itself. The major length of the line feeding the genset is some sort of plastic.When either of the 2" sections deteriorate they will crack, admitting air in sufficient quantities to squelch the fuel and starve the generator.The explanation of the cause involved Ed Newton and his propensity to NOT throw anything away. Seems he'd gotten a bargain on fuel line and it was to be used until expended. This managed to effect several model years until consumed. As my turn came around the solution was to replace the faulty 2" section at the tank, replace the fuel line run with stainless steel and also replace the 2nd 2" section as cheap insurance. Haven't had an issue since. 1 Likes
Re: Exercising generater Reply #14 – December 03, 2018, 02:16:13 pm The Cummins/Onan Operators manual covers the periodic maintenance requirements in detail. One part of the maintenance procedure that I don’t believe has been mentioned is the periodic cleaning of the “Spark Arrester” on the KY 4000 models. It is located beneath the generator near the exhaust. Other specifics such as air filter, oil filter and spark plug #’s can be useful when it’s time to restock/order parts.I’ve included pictures directly from my Onan model 4KYFA26100P generator manual to help shed a little light on these specifics. Of course if your generator model is different then these numbers and details may be moot. Just an FYI.Kent 1 Likes
Re: Exercising generater Reply #15 – December 04, 2018, 10:59:03 am Quote from: Lazy Bones - December 03, 2018, 01:23:14 pm"Keep hearing a lot about fuel line deterioration..."Yes, it was a common failure for some of us!There are two sections, each approx. 2" long, one at the point where the genny fuel line exits the main tank and another at the genset itself. The major length of the line feeding the genset is some sort of plastic.When either of the 2" sections deteriorate they will crack, admitting air in sufficient quantities to squelch the fuel and starve the generator.The explanation of the cause involved Ed Newton and his propensity to NOT throw anything away. Seems he'd gotten a bargain on fuel line and it was to be used until expended. This managed to effect several model years until consumed. As my turn came around the solution was to replace the faulty 2" section at the tank, replace the fuel line run with stainless steel and also replace the 2nd 2" section as cheap insurance. Haven't had an issue since. It is well know is auto circle years ago when they started putting alcohol in gas it would cause 'rubber' parts to fail.
Re: Exercising Generator Reply #16 – December 05, 2018, 10:54:08 am Quote from: colddog - December 04, 2018, 10:59:03 amIt is well know is auto circle years ago when they started putting alcohol in gas it would cause 'rubber' parts to fail. Wish they would ditch ethanol. We have plenty of real oil and it's now proven that ethanol does more environmental harm than good. Politicians won't do it though because they don't want to !ose the farm vote so we may have it polluting our gas forever. 3 Likes
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