Onan Generator in Class A possible overheat and overuse

[rcarpe06]

Hi, We have a 2014 Fleetwood Bounder Classic 34B Gasser with an Onan 5500 Generator. Last year, we only took short 2 to 3 hour trips in the fall when we got it. I would run the generator so that I could use the house A/C and cool the inside down.

Took our first long trip last week and coming back from Florida (90 degrees) I ran the generator at first as usual. After about 4 hours of continuous use and both A/C units running nonstop, the generator cut off and threw a fault code of 36.

After resetting the alert and letting the unit cool down for a half hour while driving, I was then able to start it back up and run it again for a few hours.

Am I pushing the unit too hard or should it be able to run continuously without interruption?

Also, on the way down to Florida, I let it run for several hours while driving for the day to power TV's and other small electronics. The A/C hardly kicked until I got close to the end of the day in Georgia.

RC

[ArchHoagland]

PlumberJohn wrote:
I have a '06 Monarch with a Onan 5500 air cooled and had a problem similar to yours.The generator would just suddenly stop running when a/c units were on.1st time I was in 100 degree weather so thought just to hot , happened again in warm wheather but would start after cooling about 15 min.but would run for only10 mins. At home in drive way started checking things out serviced gen. Problem continued, took to a repair shop and after a few hours checking things out and calling Onan they found that the gens fuel pump was getting real hot and could actually burn you if touch. Replace fuel pump and have had no problem for over a year.

Is that fuel pump visible from the opening so I could I shoot it with an IR gun?

[PlumberJohn]

I have a '06 Monarch with a Onan 5500 air cooled and had a problem similar to yours.The generator would just suddenly stop running when a/c units were on.1st time I was in 100 degree weather so thought just to hot , happened again in warm wheather but would start after cooling about 15 min.but would run for only10 mins. At home in drive way started checking things out serviced gen. Problem continued, took to a repair shop and after a few hours checking things out and calling Onan they found that the gens fuel pump was getting real hot and could actually burn you if touch. Replace fuel pump and have had no problem for over a year.

[Bumbie]

Had a similar problem with my '05 Safari Simba with the 5500 Onan. Would run for awhile then stop....30 mins or so off and would restart again. I didn't think about it until we got back from a trip....the shut off coincided with either climbing or descending a long grade. I had a low oil level. Not a lot but apparently enough to trip the low oil sensor and shut it off. Filled the oil back to full and not a problem since.

[Effy]

rcarpe06 wrote:

Effy wrote:
A few questions:
Was it hotter on the return trip?
Where is your genset located on your coach?
Were you in some traffic or not moving as fast creating airflow?
What time of the day?

-yes, it was 90 degrees most of the way home.....it was only in the 70's going down most of the way, getting into low 80's by the time we got to Florida

-genset is right behind the left front wheel....not too far from the engine

-the first time it cut off was when we stopped at a rest area for a few minutes....but there were a couple of times it cut off while going 65 steady down the road

-it was around noon the first time it cut off.....usually fine both mornings and didn't have the problems until the afternoon both days

Then I would say almost certainly it was the self protection overheat shutdown. Yours is located exactly where mine was, right behind the engine and exhaust manifold. So you get engine heat, Gen heat and road heat instead of cool air and no place for the heat to escape. Mine was so bad that the bin door was showing signs of melting on the inside and the wiring was being compromised. That's what convinced Thor to pay for the installed vented door and also paid to re-run and relocate the wires. They were catching a lot of heat too. PM if you want pics. The vented door on the gen bin seems to have fixed my problem. The forward half of the door has forward facing vents to let cool outside air in, the rear half has vents facing the other way to let hot air pass out. Good airflow. Even if you are stuck in traffic and not moving it at least lets the hot air escape instead of trapping it in the bin. Last year coming back up 95 got stuck in traffic and was in the 90's. It didn't shut down on me. Same scenario the year before it did. You may be able to find a standard vented bin door somewhere. Good luck and I hope you can work it out. Shame we have to resort to this stuff.

[Mr_Mark1]

I, too, thought that coach installed generators were all water cooled. The air cooled units remind of my 1973 Volkswagen bus I had in 1978...... it would vapor lock/get too hot.....leave me stranded until it cooled down. The fun you have when you are 20. LOL!

Learn something all the time!

MM.

[catkins]

I know little but I know this - my Onan 5500 was air cooled and shut off when the door was not fully latched allowing excess heat to build.
Big surprise was when the Onan door managed to blow off while behind a bay door. Sure hope it didn't hit anyone or anything! Genset shut down then and could not be run until the door, which acts as insulation, was replaced.

My diesel Onan is water cooled. Two different beasts.

[schwartzworld]

rcarpe06 wrote:

Effy wrote:
A few questions:
Was it hotter on the return trip?
Where is your genset located on your coach?
Were you in some traffic or not moving as fast creating airflow?
What time of the day?

-yes, it was 90 degrees most of the way home.....it was only in the 70's going down most of the way, getting into low 80's by the time we got to Florida

-genset is right behind the left front wheel....not too far from the engine

-the first time it cut off was when we stopped at a rest area for a few minutes....but there were a couple of times it cut off while going 65 steady down the road

-it was around noon the first time it cut off.....usually fine both mornings and didn't have the problems until the afternoon both days

Based on the location of the genset, i'm going to say that the combined heat of the coach engine and the genset engine are making things too hot for it. It needs more cooling air. Almost sounds like a vapor lock situation.

[rcarpe06]

Effy wrote:
A few questions:
Was it hotter on the return trip?
Where is your genset located on your coach?
Were you in some traffic or not moving as fast creating airflow?
What time of the day?

-yes, it was 90 degrees most of the way home.....it was only in the 70's going down most of the way, getting into low 80's by the time we got to Florida

-genset is right behind the left front wheel....not too far from the engine

-the first time it cut off was when we stopped at a rest area for a few minutes....but there were a couple of times it cut off while going 65 steady down the road

-it was around noon the first time it cut off.....usually fine both mornings and didn't have the problems until the afternoon both days

[Effy]

Bird Freak wrote:

Effy wrote:

mdanielson55 wrote:
It should handle the acs. Make sure when your running both acs that the elect water heaters and micro wave isn't used or coffee maker. thing to check is that the gens radiator is full on water an I run water wetter in mine as I do my cars. Doesn't hurt anything.

No idea what you mean by the gens radiator is full on water and you run it wetter than in your cars ?? This is an air cooled gen. And what is wetter water? :h

The DP guys seem to think every gen runs a water cooled engine. All 3 of my Onan 5500's have been air cooled. To answer your question about wetter water, it is really called Water Wetter. It is a chemical product you run in your coolant that makes the metal dissipate heat better to the coolant and will reduce water temps. We have used it for years in race cars.

Thanks! I learned something today.

[Bird_Freak]

Effy wrote:

mdanielson55 wrote:
It should handle the acs. Make sure when your running both acs that the elect water heaters and micro wave isn't used or coffee maker. thing to check is that the gens radiator is full on water an I run water wetter in mine as I do my cars. Doesn't hurt anything.

No idea what you mean by the gens radiator is full on water and you run it wetter than in your cars ?? This is an air cooled gen. And what is wetter water? :h

The DP guys seem to think every gen runs a water cooled engine. All 3 of my Onan 5500's have been air cooled. To answer your question about wetter water, it is really called Water Wetter. It is a chemical product you run in your coolant that makes the metal dissipate heat better to the coolant and will reduce water temps. We have used it for years in race cars.

[Effy]

A few questions:
Was it hotter on the return trip?
Where is your genset located on your coach?
Were you in some traffic or not moving as fast creating airflow?
What time of the day?

We had a similar issue a few years ago and all of the above things came into play. It was hotter on the return trip, traffic had slowed thus limiting airflow, it was the middle of the day so the road temp was much higher, and the poorly insulated RV forced the AC to run non-stop.

And as you said it was running both AC's non stop. That's about 100% demand on an air cooled gen on a hot day stuck in an enclosed bin.

My guess is it reached the high temp shutdown. Especially if it started and ran after it cooled down. Happens a lot.

Like I said earlier, I installed a vented door for the genset bin and haven't had a problem since. Thor actually recognized their design flaw and paid for the vented bin door. It can simply come down to the model about where your genset is located. Near the engine, near the exhaust, in a bin with less air flow etc. A lot of manufacturers don't install them or vent them the way they need to be to get cooler airflow. They installed mine right behind the engine. How dumb is that? They have since modified the location.

But when it's all said and done you have an air cooled generator barely sized to run everything with a high temp limiter on a poorly insulated house stuck in an enclosed bin. Thank goodness it at least has the self protect shutdown.

[Semi_Retired_Gr]

As I remember, fault code #36 is pretty general. Had it on our 7.0kw Onan when the fuel pump failed - first intermittently when it would appear we were out of gas - finally failing to operate at all.

[ArchHoagland]

rcarpe06 wrote:

bullydogs1 wrote:
Make sure your generator is getting enough air to vent...I've seen where that happens when it doesn't get enough air to vent..also check oil, as the slightest low oil could trigger it to run hotter and thus kick..also make sure your cover is on right and snapped shut correctly..incorrect venting there could trigger a heat sink and cause that to kick the sensor..even the sensor itself could be a bit faulty when on the cusp...but that's the last thing I would think..hopefully you are still under warranty..

The only opening I see is the entire bottom of the unit. The bay door is there but nothing closed off underneath. Is that the only place the air will come in from, or is there a tube I need to find that comes from the front somewhere?

Mine only vents on the bottom too.

[rcarpe06]

bullydogs1 wrote:
Make sure your generator is getting enough air to vent...I've seen where that happens when it doesn't get enough air to vent..also check oil, as the slightest low oil could trigger it to run hotter and thus kick..also make sure your cover is on right and snapped shut correctly..incorrect venting there could trigger a heat sink and cause that to kick the sensor..even the sensor itself could be a bit faulty when on the cusp...but that's the last thing I would think..hopefully you are still under warranty..

The only opening I see is the entire bottom of the unit. The bay door is there but nothing closed off underneath. Is that the only place the air will come in from, or is there a tube I need to find that comes from the front somewhere?