Generator Coolant Level

[OldForester]

I did not receive an owner's manual for our Onan QuietDiesel 7500 generator when we got our coach. Friday, after running the generator an hour to cool the coach while we were driving, I shut it down to add fuel at a Flying J. When I tried to start the generator after fueling, it wouldn't start, and I got a flashing single light on the starter switch.

Looking at the generator, I saw a message placard that said the flashing single light was a high temperature condition. I waited till the next day for the generator to cool and noticed I could not see or feel (with my fingers) any coolant in the generator fill tube. I could start the generator, however, so I'm confident the coolant must be low.

The generator has 91 hours on it and was serviced at 50 hours last fall at Cummins NW. The oil level is fine.

I also don't see any coolant leaks under the generator, so I'm not sure where the coolant went.

Until I can get my hands on generator manual, can someone please answer the following two questions:

1)How full does the coolant in the generator need to be -- near the top, or where I can at least see it when I look down into the coolant fill tube?

2)Is a general pre-mixed coolant such as Prestone (green) the right coolant to use in the generator?

Thanks for any input on this.

[OldForester]

I did not receive an owner's manual for our Onan QuietDiesel 7500 generator when we got our coach. Friday, after running the generator an hour to cool the coach while we were driving, I shut it down to add fuel at a Flying J. When I tried to start the generator after fueling, it wouldn't start, and I got a flashing single light on the starter switch.

Looking at the generator, I saw a message placard that said the flashing single light was a high temperature condition. I waited till the next day for the generator to cool and noticed I could not see or feel (with my fingers) any coolant in the generator fill tube. I could start the generator, however, so I'm confident the coolant must be low.

The generator has 91 hours on it and was serviced at 50 hours last fall at Cummins NW. The oil level is fine.

I also don't see any coolant leaks under the generator, so I'm not sure where the coolant went.

Until I can get my hands on generator manual, can someone please answer the following two questions:

1)How full does the coolant in the generator need to be -- near the top, or where I can at least see it when I look down into the coolant fill tube?

2)Is a general pre-mixed coolant such as Prestone (green) the right coolant to use in the generator?

Thanks for any input on this.

[OldForester]

I'm responding to my own message.

I visited Guaranty RV in Indio, CA, today and found the answers to my questions. The coolant level marks are located on the very front of the generator and I didn't move my head into position to see them.

I also found out the 50/50 ethylene glycol/water mix is fine to use in the system.

Finally, I learned the procedure is to fill the coolant to the "cold/min" mark, run the generator under load for 2 to 3 minutes to release trapped air, and re-fill to the "cold/min" mark.

Guaranty also said these generators are sensitive to temperatures above 110 degrees and at altitude; neither of which I've yet experienced, and I'm sure others in the forum have. It was 95 degrees ambient and hotter than that on the pavement Friday so that may have contributed.

[Eusefull]

Hello Old Forester ~

found your post doing a search as I am looking to see if changing the oil and filter is a DIY type of job...or if I need to take it in for service. My generator is very sluggish to start even after priming the switch before hitting ON. So I recently found this online site that allows you to download an owner's manual.

If you haven't already got one, here's the link:

http://www.cumminsonan.com/rv/produc...e?gensetId=135

the first 3 documents are the PDF's

Eusefull

[Rick Coleman]

Old Forester- I note you are in Indio. Are you down for the winter? I'm planning on moving my coach back to Indio for the winter...was going down this Friday, fires and traffic permitting. I got the impression that Guaranty was closing their Indio store and opening one in Arizona...must have been a bad rumor.

Rick

[Old Scout]

Very interesting--after five years of travel, I never knew there was a fill mark on the front of the genset. Once you get your manuals you will find out that the fill spout on the genset is to the overflow jug, not the radiator. Accordingly, you have to fill the jug to the neck or to the "mark" then run the genset thru a hot/cold cycle to get the coolant to syphon. If you are game, you can remove the top of the genset and see how much, if any, dirt/dust has collected in the engine/generator cooling fins. Once there, you can also see if the rubber tube between your coolant overflow jug and the radiator cap is kinked--mine was so bad I am not sure any coolant could flow back/forth(be careful trying to remove the radiator cap assembly--its really close quarters and there are some electrical connections[starter button) mounted to/near the assembly.

Changing oil is a snap--like your lawn mower/garden tractor. On some gensets, the trap door that covers the drain plug/oil filter sometimes swings down against the exhaust pipe/bracket--what a pain. With only 91hrs, you shouldnt need to change either the air or fuel filters (about every 500hrs).

[Dale777]

Old Scout,

You note that, "...the rubber tube between your coolant overflow jug and the radiator cap is kinked..." I suggest checking with an Onan Service center about this kink.

I've had my 7.5KW Onan genset serviced at Onan on both a 2001 and a 2006 Alpine Coach in which this hose was kinked. In both cases, the Onan service department told me that the kink was proper.

[takepride]

OldForester:

I've had the same problem and flashing lights with my genset. It was solved by holding the starter button in the OFF position for 30- 60 seconds to purge air from the fuel line and preheat better than the normal method. Then I push the ON for the normal length of time.

My experience has also been that this procedure (in spite of the instruction manual) often needs repeated to work. The genset really kicks around, shakes, rattles and burps a bit. After a good start the problem goes away until I let the tank get too low again.

Of course, now that I have my new and functioning fuel sender installed, I can better keep my tank at a reasonable level.

[OldForester]

Euseful-

Thanks for the information on the site with the Onan manual. I have downloaded and it is helpful.