Why running your Onan monthly is important

[Ray,IN]

Originally Posted by MSHappyCampers

Thanks for the tip! I exercise our genny about 30 minutes each month with both A/C units running.

Cummins/Onan says 2 hours monthly @ ½ load.

[donr103]

Great job.. but you show exactly why to change coolant a lot.. and same thing in rv eng.. I have seen this too many times.. coolant gets old and eats through everything.. by the way.. ever think about upgrading gen eng oil cooler ? I have a gassed onan 5500 air cooled.. I am adding oil cooler.. it seems to me.. that when you need gen.. it's hot outside.. what temp thermostat do you run ? Good job.. keep us posted

[corprimo]

Originally Posted by Latech

Looks like you added another failure point for coolant leaks. Not trying to be flip, just stating the obvious.
The sensor looks very corroded.
It would be wiser to change the coolant every year to keep the electrolysis in check as coolant has anti corrosive properties and they diminish or become "depleted" after so long
Also a sacrificial anode would help. Usually a piece of zinc, that is bolted to the engine , but better yet ,immersed in the coolant .

just sayin

Sensor #2 does not contact coolant.

[corprimo]

Once you remove Gen, access is easy. Took me about 5 hours to remove Gen by my self.

[OldWEB]

Originally Posted by corprimo

Sensor #2 does not contact coolant.

Then what do you expect it to do may I ask?

[corprimo]

Sensor 2 is screwed into a recess in the thermostat housing , not a hole. It has no contact with the coolant so a leak is impossible.

[corprimo]

I watched a YouTube video where another owner totally stripped his sensor but couldn’t remove it. He figured out the alternate location and tested it. When the generator started to overheat, the sensor did It’s job and shut down the generator. The base of the sensor in this location is right up against the metal thermostat housing, about 4 inches above the original location.

[BD104X]

If your generator is out, you should change the temp sensor, the thermostat and the water pump belt. I have a friend that works on those regularly and he says that they are very reliable units aside for on those 3 things. The belt especially as it will deteriorate with age.

[nehog]

Yours's is an example of why a coolant flush is important!

[Steve 716]

It is especially important to regularly exercise your generator if you have a gas powered RV. Ethanol will harm or destroy the bowl in your carburetor and the only fix is to rebuild it. This has happened to me once and to RVing friends a number of times. After mine was rebuilt I ran it under load every two to three weeks, no longer. Now I have a diesel pusher and run my generator every month under load.

[Jchemie]

When I first aquired my new to me class A, I changed all the belts and fluids on the coach and the 5.5k quiet Onan diesel, a 2004 model that was then 11 yrs old. Mine doesn’t slide out either. What a PITA to work on it while still in the vehicle! The rv shop where I bought my genset parts gave me some good advice, replace the thermostat while I was in there ($18). With only 100 some hours on it, he said it was probally the original thermostat and prone to fail. His experience with them was the same as you encountered, most were self-welded in place. Mine was in the inital stage of corrosion (at 100 hrs!) but with a lot of grunting, a cheater bar, a superior penetrating oil and some well versed cuss words it came out in one piece. Of course it was at the furthest rear most portion of the motor and awkward to get to. After re-tapping the threads I replaced it with a new sensor coated with copper anti-sieze on the threads and two band aids for my fingers. Now at 222 hours all is well. Yes, new anti-freeze after a chemical flush was done.
Note: mostly all sensors use the thread connection as a ground. Teflon tape and pipe dope will limit or completly eliminate this grounding. Using a copper based anti-sieze gives it good grounding and prevents seizing. The anoid is a great idea, but it has to be in contact with the fluid and grounded, again, copper anti-sieze should be used.

[smkymtnboy]

Originally Posted by corprimo

I confess, I have been lax regarding the monthly exercising of my Onan 7500 Quiet Diesel Generator on our '04 Journey. I figured if we stopped at a Rest Area and warmed up lunch, that would count. It doesn't! Ours started quitting after a minute of run time with an over heating code, so I finally dropped the damn thing with a motorcycle jack, raised the front of the coach up into the stratosphere, and rolled the Generator into my garage. The Temp sensor did NOT want to come out. I finally froze a chunk of ice 2" in diameter, then used a heat gun on the housing while letting the ice melt down on the sensor, and it finally came out - but not all of it. It was corroded so bad I had to punch the innards down out of the tube where it's mounted. I found a YouTube video about relocating the sensor, and decided to give myself a "plan B." I bought two sensors from Cummins at $40 ea. and mounted one in the cleaned out original location. The Thermostat housing has a round recess that doesn't go through to the coolant, and it is the perfect size to be tapped for a second Sensor, so I installed one there as well, and ran wires from both of them out to the front of the generator and if the #1 sensor quits working, I can just change the wire over to #2. Also put in new belt, thermostat, radiator cap, changed oil and all filters, and now I'm going to do a serious radiator flush. When exercising the Generator, if you don't get it up to operating temperature for a while, the thermostat isn't going to open, and there will be no circulation of the coolant at the location of the Sensor, and it seriously gets gunked up and will fail. Lesson learned!

u can drill a hole in the housing to allow coolant to reach sensor. i did mine the same way. my gen was serviced and this temp sensor was corroded and stuck. fortunately, my gen was on a slide. flush,with fleetguard restore plus the other stuff will NOT cut it literally speaking. anyone who tackles this easy project should remember the anti seize listed in the post above. these sensors seem have a short life and go bad sooner than most of us appreciate.

[BobDye1]

Hi - I installed a gas-line shut off on my generator (Cummins Onan 4KYFA26100). When I put the RV into 'storage', I run the generator for a while then shut off the gas line and let the generator die. Does anyone predict a problem with that?

[Oregon RR]

Originally Posted by BobDye1

Hi - I installed a gas-line shut off on my generator (Cummins Onan 4KYFA26100). When I put the RV into 'storage', I run the generator for a while then shut off the gas line and let the generator die. Does anyone predict a problem with that?

Exactly what I've been doing for the last 11+ years - no problem-o. Of course mine is only a 4000 watt generator, so YMMV.