Help needed with Onan generator problem

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Phil Hendrix

Phil Hendrix

Member
Joined
Dec 23, 2007
Posts
24
Location
Chicago
Hi all,
My American Heritage has a 10kw Onan generator with approx. 3900 hours on it. The previous owner experienced a problem with it about 18 months ago with it wanting to shut down on him due to the high temperature indicator. He took it to the local RV dealer where he bought the RV from and they could not determine why it was shutting down on him so they concluded it needed a new radiator. Recently it has started shutting down on me for the same reason. At first it was every now and then but now it is consistently doing it after about 10 minutes of running. The fluid level is good. When I look at the control monitor inside the coach and scroll to the reading of the generator temp it say 104 at all times, whether the unit is running or not.

What could be my problem? Sensor? Radiator? Fan belt? Water pump?

Just curious also....is 3900 hours alot?

I just bought this RV about 6 months ago and loving it!

Thanks for all the great advice I have been reading here, Phil
 
Have you checked the oil level.  There is a low oil shutoff switch I believe.  I did talk to a guy at American Coach service once that related a similar problem which was caused by some paper blocking the cooling ais flow. 
 
If the code is high temp then there are several possible issues

One is radiator, one is sensor, water pump, fan belt, fan, obstructed air flow, obstructed coolant (water) flow inside the engine, other internal issue with the engine, bad timing, bad carbrator settigns, Lots of possible causes.
 
Yeah, 3900 hours is a fairly hefty amount.  Onan recommends that the fan belt be changed every 1000 hours - I'm told it is prone to stretching and begins to slip. That would seem a likely explanation for your symptoms. The belt is a bear to get at - it's at the back of the genset and you have to remove the rear cover to reach it (and that means removing top and maybe side covers as well on most big Onans).

It's hard to rely much on what a previous owner said/did and what the prior dealer said as well. Why not take it to a Cummins/Onan shop and have them check it out? Most of them are excellent. Look for one that carries the "Coach Care" designation - they are accustomed to working on motorhome systems.
 
RV Roamer said:
Yeah, 3900 hours is a fairly hefty amount.  Onan recommends that the fan belt be changed every 1000 hours - I'm told it is prone to stretching and begins to slip. That would seem a likely explanation for your symptoms. The belt is a bear to get at - it's at the back of the genset and you have to remove the rear cover to reach it (and that means removing top and maybe side covers as well on most big Onans).

It's hard to rely much on what a previous owner said/did and what the prior dealer said as well. Why not take it to a Cummins/Onan shop and have them check it out? Most of them are excellent. Look for one that carries the "Coach Care" designation - they are accustomed to working on motorhome systems.
Click to expand...

I talked to couple other people today that said it was the belt. They said they had the same unit and it has happened to them several times. I will remove the covers and check it out. Thanks                                                                 
 
John In Detroit said:
If the code is high temp then there are several possible issues

One is radiator, one is sensor, water pump, fan belt, fan, obstructed air flow, obstructed coolant (water) flow inside the engine, other internal issue with the engine, bad timing, bad carbrator settings, Lots of possible causes.
Click to expand...

I also wondered about the thermostat being stuck??
 
Ron said:
Have you checked the oil level.  There is a low oil shutoff switch I believe.  I did talk to a guy at American Coach service once that related a similar problem which was caused by some paper blocking the cooling ais flow. 
Click to expand...

I did check the oil....it is fine, dirty and needs to be changed, but the level is good. I was planning to do a complete service on it anyway.
 
slumbert55 said:
just a thought have you tried a 12v fan on the board ???
                                                                             steve
Click to expand...
Do you mean the fan on the radiator?
 
The belt in my 7.5KW Onan Quiet Diesel drives the water pump. There is no radiator fan per se, but there is a powered "flow through" air system that draws air into the box, over the engine and out through a exhaust vent, some of it passing through the radiator on the way. I was running mine with the top cover off and found that it overheats to the point where the high temp shut down occurs in about 8-10 minutes. Putting the top cover on fixed that, so apparently the box serves to channel the air flow through the radiator.
 
RV Roamer said:
The belt in my 7.5KW Onan Quiet Diesel drives the water pump. There is no radiator fan per se, but there is a powered "flow through" air system that draws air into the box, over the engine and out through a exhaust vent, some of it passing through the radiator on the way. I was running mine with the top cover off and found that it overheats to the point where the high temp shut down occurs in about 8-10 minutes. Putting the top cover on fixed that, so apparently the box serves to channel the air flow through the radiator.
Click to expand...
Now I never thought about that....I will give that a try. But I do remember it shutting down on me as I was driving down the road. Thanks, Phil
 
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