Generator maintenance

Generators should be run under load at least once a month. I run mine about 20 minutes, which should be enough to get the oil temp up to the point where the moisture in the crackcase gets boiled away. Running under load will also remove moisture from the windings and burnish in the brushes.

Yes, in order to run under load you'll need to disconnect. I would get the genny running for a minute then trip the breaker on the pedestal to test the transfer switch. Then turn on an air conditioner. I have an electric heater I use for a load in the winter.

We run it monthly also and try for 20-30 minutes under load. Summer is easy disconnect AC, start genny, turn on air conditioner after power comes on. Winter we run it a little longer but use the furnace for load if to cold for AC.

Dave

I believe there is a lot of misconceptions here. a great many diesel get/sets don't get started for many months in fish and hunting camps across the north country, Yet they start and run fine year after year.

Onan certainly recommends that you "exercise your generator" by running it under load for an hour each month.

Certainly is a "best practice".

I would definitely disconnect from shore power before firing up the generator as the power source will default to the generator/switch sources under load via the transfer switch.

If done while on shore power, it is a bit tough duty for the contact relays in the transfer switch.

Tom/Barb wrote:
I believe there is a lot of misconceptions here. a great many diesel get/sets don't get started for many months in fish and hunting camps across the north country, Yet they start and run fine year after year.

I believe most owners prefer to follow Onan's Recommendations for Maintenance. Usually least costly in the long run.

My MH sits (or did sit this year) from Oct to May. I did not start the diesel motor during that period as I had minimal insurance and could not take it on the road. I did start it and take it for an hour run in May.
Most "experts" agree that you should only run the motor if you are really going to bring everything up to temp. Running for 10 or 15 minutes on the motor could do more harm than good.

The diesel genset was actually used this winter for over 24 hours during the winter during a power outage in the S&B - otherwise it to is not used until the spring and then under load for an hour.

I do add a cold weather additive to the diesel each fall, just in case I do need the MH or genset during the winter.

I grew up in farm country and most diesel vehicles were just parked in the fall and left til spring. Some of these were decades old!.


Now that I am retired I expect to use my MH year round but still sit in one place for several weeks (down south!) during the winter.

Chris

cvbdsl wrote:
My MH sits (or did sit this year)
I grew up in farm country and most diesel vehicles were just parked in the fall and left til spring. Some of these were decades old!.
Chris

That's where I am with this, Onan has a CYA to protect. Of course they want you to run your gen/set, they sell gen/sets.

Our Generator is a 7500 Onan, it has a 3 cylinder Kobota diesel, that like all diesels carbon up on the interior really quickly, that black gooey stuff is a really good corrosion protector. So it doesn't corroded inside, the cam and lifters run mostly in an oil bath, so they are very well protected too.
The top of the engine is the combustion chamber. Diesels burn an oil, the combustion is always oily. and thus protected too.
Our Onan was built in 1998, placed in our motorhome in 1999, and sold as a 2000. It now has 43 hours run time. It has had 1 oil change and filter in 20 years, it starts each and every time we need it, and works as it should, and will continue to do so for as long as we need it.

jplante4 wrote:
Generators should be run under load at least once a month. I run mine about 20 minutes, which should be enough to get the oil temp up to the point where the moisture in the crackcase gets boiled away. Running under load will also remove moisture from the windings and burnish in the brushes.

Diesels make about 1/4 the water that a normal gas engine does. they use a lot less fuel, thus can't make as much water.

What you are doing is simply this.
You left water in your engine the last time you shut down, simply because water is being made anytime the engine is running.

So now you want to start up to get rid of the water in your engine, you run it until it's hot enough to get rid of the water, but you just made more then shut down.

Isn't this where we came in?

We all know water is heaver than oil, it will settle to the bottom of the oil pan and stay there until disturbed, so what did you accomplish by starting the engine and disturbing the water that was there?

OBTW most all of our generators now are brushless alternators, in a sealed unit. The water you are worried about can't get in.