Genny Service

[Moder2]

Finally got around to finding the recommended Coolant for the coach. Found the CAT stuff at the Mack dealer in town, but he didn't have the "Non Mixed" stuff... 3 more places, and ended up at Fabick. Price was pretty crazy at $20.13 a gallon, and was surprised that his price on the 50/50 mix was only 10.83, compared to the Mack dealers 15.++...

Anyhow, didn't feel like getting too dirty today so I decided I would focus on just the generator today. I didn't know how well it was cared for in the past, and it does have lots of hours on it. Plus, I didn't want one type of coolant for the generator, and another for the coach. Pretty straight forward once I found the radiator cap under the little panel....

What I found out today... don't run the genny with the top cover off! It WILL Overheat. Every time. It is essential for the fan to be contained, as to push air through the tiny radiator. Don't ask how I finally came to this conclusion, and a confirmation call to Onan, but the $7.69 worth of coolant on the ground had a lot to do with it.

The Radiator fill is located under the little knockout panel, near the switches. After finding it I also found the words "Radiator fill under here" in bold letters. Duh. Knowing that, one has no reason to remove the top cover, which would save about an hour of messing around.

There is just shy of a gallon of coolant in the system. I drained it, filled with water, ran it, drained, flushed, and flushed a third time before switching to the ELC.

Secondly, well, actually the first problem I had today was the oil filter. I changed the oil in the genny just before leaving for Saint Louis. It was inconvenient for me to get an Onan filter, so I used a Mobil 1 filter, with the thinking that it is a premium filter and would be as good if not better than the Onan. It's not, and I had to change it today again. USE AN ONAN! The Mobil 1 filter either doesn't have or has too strong of a blow off device, and will cause a Low Oil Pressure situation on startup. Once the oil warms it is fine, but with thick oil the generator is starving for lubrication! This is the first time I have used a Mobil 1 filter on anything. Normally I am pretty stuck on either OEM or Wix, this event has even more so made that my initial thoughts were correct.

I am glad I did pull the cover, since I now know how things look under it. I found out today is that Cummins doesn't make the engine! It is a Kubota. A Very simple well designed engine, and the way things are put together to work together in an interesting way.

Oh, it is an Onan 7500 Quiet Diesel

More to come when I get the will to change the coach over.

John

[Moder2]

Finally got around to finding the recommended Coolant for the coach. Found the CAT stuff at the Mack dealer in town, but he didn't have the "Non Mixed" stuff... 3 more places, and ended up at Fabick. Price was pretty crazy at $20.13 a gallon, and was surprised that his price on the 50/50 mix was only 10.83, compared to the Mack dealers 15.++...

Anyhow, didn't feel like getting too dirty today so I decided I would focus on just the generator today. I didn't know how well it was cared for in the past, and it does have lots of hours on it. Plus, I didn't want one type of coolant for the generator, and another for the coach. Pretty straight forward once I found the radiator cap under the little panel....

What I found out today... don't run the genny with the top cover off! It WILL Overheat. Every time. It is essential for the fan to be contained, as to push air through the tiny radiator. Don't ask how I finally came to this conclusion, and a confirmation call to Onan, but the $7.69 worth of coolant on the ground had a lot to do with it.

The Radiator fill is located under the little knockout panel, near the switches. After finding it I also found the words "Radiator fill under here" in bold letters. Duh. Knowing that, one has no reason to remove the top cover, which would save about an hour of messing around.

There is just shy of a gallon of coolant in the system. I drained it, filled with water, ran it, drained, flushed, and flushed a third time before switching to the ELC.

Secondly, well, actually the first problem I had today was the oil filter. I changed the oil in the genny just before leaving for Saint Louis. It was inconvenient for me to get an Onan filter, so I used a Mobil 1 filter, with the thinking that it is a premium filter and would be as good if not better than the Onan. It's not, and I had to change it today again. USE AN ONAN! The Mobil 1 filter either doesn't have or has too strong of a blow off device, and will cause a Low Oil Pressure situation on startup. Once the oil warms it is fine, but with thick oil the generator is starving for lubrication! This is the first time I have used a Mobil 1 filter on anything. Normally I am pretty stuck on either OEM or Wix, this event has even more so made that my initial thoughts were correct.

I am glad I did pull the cover, since I now know how things look under it. I found out today is that Cummins doesn't make the engine! It is a Kubota. A Very simple well designed engine, and the way things are put together to work together in an interesting way.

Oh, it is an Onan 7500 Quiet Diesel

More to come when I get the will to change the coach over.

John

[ChasA]

John,
Re your genset oil filters. Some oil filters have a bypass built in so that all the oil doesn't go through the filter media, some other oil filters do not have this bypass, therefore all the oil must go through the filter. My guess is that the Onan is a bypass type and the mobile 1 filter is a non-bypass type. Before replacing an oem filter with a different brand or number you should carefully compare the tops (ie, the area where the filter mates to the engine)to make sure the gasket, holes, and channels are the same.

[John_Canfield]

John - the Japanese make exceptionally good small diesels. They might also make exceptionally good large diesels, but I have no personal experience with those.

One of our smaller sailboats had a little Yanmar two cylinder 15 HP diesel and it was a faithful performer. My current tractor is a Kubota with a three cylinder 30 HP diesel and the engine hasn't given a lick of trouble in the ten years of ownership.

We also have the Onan Quiet 7.5 and have an intermittent problem with it but I don't think it has anything to do with the engine. We have an appointment with Cummins in Phoenix in a couple of weeks to have this looked at.

[KIX]

John,
Your post reminded me that I have to change the coolant in our genset too. Thanks
PS did you see the photos of the recovering of the chairs and window stuff we did? www.kixrocks.smugmug.com then go to "Our Motorhome"

[Moder2]

ChasA -- Yep, aware of what makes an oil filter tick and I thought I could get away with it. It it was pretty similar... I was wrong.

John -- Please let me know what happens at Cummins. I certainly didn't take offense that it was a Kubota, I have always had seen and heard good things about Kubota. Derek's father's tractor is a Kubota and he just loves that thing. I just found it very strange that I never heard of cummins using the Kubota engine. It is a great design from what my feeble brain can tell. And with that kind of simplistic technology imagine what the automakers could be doing with it? I just want a small (but big enough for me) 4x4, diesel pickup.... I am sorry I digress...

Kix, Yes, I did see your pics, you did a splendid job. Thanks for sharing them.

John

[SargeW]

I was surprised as well when I discovered that my Onan 7500 was a Kubota diesel. I also wasn't disapointed either. Over 30 years ago I was using a Kubota tractor with a 3 cylinder motor when I was working for a concrete company. I worked that sucker HARD every day and never had a bit of trouble with it. I have great faith that my Onan will provide years of reliable service

Sarge

[DonavonP]

The horizontal twin air cooled gasoline engine often referred to as an ONAN engine is (was) made by Linamar.

I'm also a big fan of the Kubota diesel.