Generator - High Temps

We had a 2017 class c MH with an Onan generator mounted on the side and in summer temps it would routinely shut off due to high temps. I’ve seen some new toy haulers (Forest River mostly) with vented doors on the generator door like some of the latest motorhomes.

Has anyone had issues with their generator in high temps without a vented door? Given the front location of the generator, a vented door seems like a bad idea when driving in the rain but wondering what others have experienced.
 
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centerline

Well-known member
the newer ONAN generators need the be kept sealed in their case to prevent overheating.... they are a different design than they were 20 years ago, and they draw the air in from the bottom by a large fan, where it flows over the generator head and cycles thru the cooling fins on the engine, and then passes through to, and flows over, the exhaust pipe and muffler, carrying excessive heat away as it leaves the unit at the bottom of exhaust pipe end of the generator....

having any doors or panels open on the generator while its running will let the air escape before it has a chance to absorb and carry the heat away...which, the enclosure is what helps keep it quiet also
 

porthole

Retired
We had a 2017 class c MH with an Onan generator mounted on the side and in summer temps it would routinely shut off due to high temps. I’ve seen some new toy haulers (Forest River mostly) with vented doors on the generator door like some of the latest motorhomes.

Has anyone had issues with their generator in high temps without a vented door? Given the front location of the generator, a vented door seems like a bad idea when driving in the rain but wondering what others have experienced.


9+ years with our Cyclone and used the generator a lot.
The RV's with the vented front door look kind of ugly, don't care for it.

We've never had an overheat issue and there were days where the gen ran all day running two AC's in 90 degree temps.
Only thing I did different on long run days was to leave the baggage door open, that compartment does get hot and the heat just transfer up to an area you are trying to cool.

The air cooled Onan's like yours need to have the front gen enclosure panel on and attached properly. Do not take the access panel off thinking it will help cool it.
 
I'm referring to the bay door having a vent cut in it (see picture below) and not removing the generator cover. I know the genset cover needs to remain. Our 4k Onan would overheat a lot in 90 degree weather going down the road and am wondering if we'll have the same issue with this one. On hot summer days I'd like to run the genset traveling so the coach isn't 110 when we park.

vented gen.jpeg
 

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porthole

Retired
I'm referring to the bay door having a vent cut in it (see picture below) and not removing the generator cover. I know the genset cover needs to remain. Our 4k Onan would overheat a lot in 90 degree weather going down the road and am wondering if we'll have the same issue with this one. On hot summer days I'd like to run the genset traveling so the coach isn't 110 when we park.

View attachment 65040


I know what doors you are referring too. I don't like the way they look and have never seen one that was a few years old that looked anywhere near as good as it did when new.

We frequently would stop an hour or so out on hot days, start the gen and run both AC's on max. Never had an issue.
 
I know what doors you are referring too. I don't like the way they look and have never seen one that was a few years old that looked anywhere near as good as it did when new.

We frequently would stop an hour or so out on hot days, start the gen and run both AC's on max. Never had an issue.

Good to hear it's worked well because I don't like the look either but would rather have the vent and a working genset if necessary.
 

centerline

Well-known member
I'm referring to the bay door having a vent cut in it (see picture below) and not removing the generator cover. I know the genset cover needs to remain. Our 4k Onan would overheat a lot in 90 degree weather going down the road and am wondering if we'll have the same issue with this one. On hot summer days I'd like to run the genset traveling so the coach isn't 110 when we park.

View attachment 65040
dont cut a hole in the bay door, as then it will accumulate dust, rain and sand from the road... if you feel more ventilation is necessary, go inside the bay and look at cutting openings in each end of it... this will allow cross breeze ventilation and still keep it sealed from the elements, especially when traveling... the down side is, unless you have an enviromental shield protecting the openings underneath the genset, as you are traveling with the genset running, its going to suck in everything your wheels kick up on the road... wet, salty road spray, sand, dirt, dust and whatever else...

if the conversion was made to suck the air from INSIDE the bay, and then have it exit as normal, it would keep the bay cool with the constant exchange of air (all the time its running) and keep it protected from ingesting road filth when traveling with it running... , basically, the cooling issue is going to be a lot less of an issue than what gets drawn up in the genset and causes it to age prematurely, and need serviced more often...
 

esscobra

Well-known member
i did alot of research before purchasing my 7k onan for my bighorn - i think you will find the issue you described is from when traveling - the hot exhaust air is being sucked back into the intake and unable to properly cool the unit - there are many onan aricles on proper cooling and height and distance off the ground and even installing air diverter/deflectors to prevent this - the there is an onan manual about overheating and checking the air inlet temps - and i remember that depending on how they are mounted they should not be run while moving- which is most likely whats happening when traveling down the road is wind is pushing hot exhaust air into path of intake - i would fab some metal to better isolate the intake from the hot exhaust air
 
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