2004Endura 6340 diesel generator

[Mike1931]

We have a 2004 Endura 6340 duramax, with a 5500 watt diesel Cummins/Onan diesel generator, with 1400 hours, Model # 5.5 HDKBA-2733B Spec B
120b KVA 5.5 KW5.5, that has in issue in the electrical making part.
The diesel engine runs good with main breakers off at generator. When the breakers are turned on the generator quits after 10 to 15 minutes, the start/stop switch blinks a code meaning an over heat situation.

So we are either looking for a repair facility for the electric makin happnener of the unit, or a complete used/new replacement unit.
Thanking you’se guys in advance.
Mike Root
Saint George Utah

 

[THenne1713]

If overheat, maybe a loose belt/ bad thermostat, but otherwise, if code read wrong, failing fuel pump fits your symptom.

 

[Bike Dr]

They pick up road grime over time that will clog the radiator. Get some core cleaner it should do the trick and will clear the overtemp code. you have a few hrs on it and that is an indicator because it has been used 1400hrs. I have seen it quite a few times over the yrs. And as mentioned check the belt.

LIFE IS GOOD!!!! LIVING IT!!!!

2005 41'4 ATRIUM SE CAT
2017 20' closed trailer
2014 Streetglide Special
2010 Mini Cooper or 04 H2

 

[Mike1931]

They pick up road grime over time that will clog the radiator. Get some core cleaner it should do the trick and will clear the overtemp code. you have a few hrs on it and that is an indicator because it has been used 1400hrs. I have seen it quite a few times over the yrs. And as mentioned check the belt.

LIFE IS GOOD!!!! LIVING IT!!!!

2005 41'4 ATRIUM SE CAT
2017 20' closed trailer
2014 Streetglide Special
2010 Mini Cooper or 04 H2

Bike Dr.
My story is so long it’s crazy.
Radiator has been both washed (sprayed) from the out side and flushed.
The block has been flushed.
Belts changed.
Bypass hose replaced.
Both radiator hoses flushed.
Thermostat replaced.
Temp sensor replaced.
Water pump replaced.
Even the fuel pump was replaced.
Its been in and out so many times that i may have to enlarge the mounting bolts, just kidding.
Its runs fine with out a load on it. As soon as you flip on the “NEW Breakers” that are on the generator, the generator will run 10 minutes and shut down, and throw an over heat code.
I honestly believe it’s a stator issue. But since Cummins Onan has discontinued the 5500 watt, most likely non parts available either. Ive had a authorized Cummins Onan dealer repair store quote me $440. For two hours of diagnoses. Of course that comes with no guarantee parts ar available.
Im in it over $2,500 with no results.
I believe i can shoe horn a 600 watt in the same compartment with some metal fab work.
Then i will have my 5500 up for sale. Hopefully someone here blew up their engine.
Mike in Saint George Utah

 

[THenne1713]

Have read of OTHER ONAN DIESEL that had your symptoms and (apparently FALSE HIGH TEMP Code) and issue was actually a code 36 and CURE was a new electric fuel pump/ lift pump ($25-$50 on Amazon). GOOD LUCK

 

[Mike1931]

Apparently our issue is with the electrical makin happner.
After checking engine oil and engine coolant levels first. Then moving on to, replacing the fuel pump, thermostat, temp sensor, water pump, water pump bypass hose, both belts, washing the radiator find, flushing the engine block, flushing upper and lower radiator hoses, and last replacing both electrical breakers on the generator. And $2,500 later to “NO” resolve!
Since Cummins Onan has discontinued the 5500 watt Diesel Generator, electrical parts are few.
$12,000 later, We have moved forward to a new Cummins Onan 6.0 watt diesel unit. Yes there will be some compartment alterations, to make it fit.
Mike Root
Saint George UT
2004 6340 Endura Gulfstream

 

[proost]

Apparently our issue is with the electrical makin happner.
After checking engine oil and engine coolant levels first. Then moving on to, replacing the fuel pump, thermostat, temp sensor, water pump, water pump bypass hose, both belts, washing the radiator find, flushing the engine block, flushing upper and lower radiator hoses, and last replacing both electrical breakers on the generator. And $2,500 later to “NO” resolve!
Since Cummins Onan has discontinued the 5500 watt Diesel Generator, electrical parts are few.
$12,000 later, We have moved forward to a new Cummins Onan 6.0 watt diesel unit. Yes there will be some compartment alterations, to make it fit.
Mike Root
Saint George UT
2004 6340 Endura Gulfstream

Mike,
Sorry you ultimately had to bite the bullet on a new generator. I had to do the exact same thing last year but went to a QD8000 from an older Generac 75D. It's a hit to the wallet but we've never looked back.

If you still have your 5500, hopefully you can ultimately find a shop to take a look at it and get it going again so you can sell it for a decent amount. I know of a guy in AL (Charles at Kimbroughs RV & Power) who is an ace with Onans but unless you travel with extra space, probably won't be helpful to you unless you get him on the phone to get his thoughts on options for you.

 

[Mike1931]

And as Paul Harvey, used to say
“Now The Rest Of The Story”
You see… HPV Cancer has taken both my voice box and tongue. I’ll never be able to talk on the phone. I use text to communicate, quite a number of repair shops don’t have a text line. And their email addresses suck too.
You ever tried to contact Cummins Customer Service? Thats enough with the whoa its me crap. NOTE; foe anyone reading this, November 11th 2024, be assured i have a great running 5500 diesel generator engine, with 1,400 hours and a “S” load of new parts on it, because the shops i took it to didn’t diagnose the problem, they just threw new parts at it.
This unit is for sale as is at this point. Reasonable offers will be taken into consideration.
Mike Root
Saint George Utah

 

[L Spillman]

We have a 2004 Endura 6340 duramax, with a 5500 watt diesel Cummins/Onan diesel generator, with 1400 hours, Model # 5.5 HDKBA-2733B Spec B
120b KVA 5.5 KW5.5, that has in issue in the electrical making part.
The diesel engine runs good with main breakers off at generator. When the breakers are turned on the generator quits after 10 to 15 minutes, the start/stop switch blinks a code meaning an over heat situation.

So we are either looking for a repair facility for the electric makin happnener of the unit, or a complete used/new replacement unit.
Thanking you’se guys in advance.
Mike Root
Saint George Utah

I have a Generac diesel generator and had the same problem. It would start great and run for about 11 minutes under load and shut down. After it cooled down it could be restarted but with the same 11 minute results. I removed the over temp shut down probe and tested it and it functions properly. I then removed the thermostat and tested it and it functions properly. I then searched for the radiator cap to test it and after much searching I finally found it on the opposite end of the generator under a screwed down plate. Nothing seemed to be wrong with the cap. I then decided to drain all the coolant from the system, after much searching for a drain. Drained the coolant into a bucket and got about 1 1/2 quarts. The system holds 1.4 gallons or almost 6 quarts. There is no way to pour coolant into the radiator unless I were to remove the generator from the coach. A trip to Harbor Freight to buy a pump and an inspection mirror solved that problem. I pumped in a gallon of Peck 50/50 coolant and started the unit. Once the thermostat open I was able to pump in the other .4 gallon of coolant. The unit now runs at full load for several hours. Note: the level in the coolant expansion tank, that you can see, is not the coolant level in the radiator. Thanks for listening. Generac was absolutely no help and Gulf Stream was no better.

 

[Mike1931]

L Spilliman
Thanks for the tips..,,
Note ours is “was” a Cummins/Onan 5500 watt generator. It was been out and on the ground for repairs many times, that im surprised the bolts hadn't wore out! We actually replaced the fuel pump, temp sensor, thermostat, water pump, water pump by pass hose, both belts, both upper and lower hoses. Flushed engine block, flushed radiator, cleaned radiator fins, changed coolant twice during testing. Yes we did get the correct amount of coolant back in ithe generator each time.

It has mow been replaced with a,
Cummins/Onan 6.0 (6000) watt unit. Although, the decal on the outer panel showed 8.0 QD “Quiet Diesel”
In reality i’m not positive of just what we have. The serial decal shows it’s a 6.0
It’s making electricity and charging batteries!
Confused Mile in
Saint George Ut

 

[Mike1931]

If overheat, maybe a loose belt/ bad thermostat, but otherwise, if code read wrong, failing fuel pump fits your symptom.

It isn't an engine issue. Spent $2,500 finging out that its the generator half of the unit that needed repairs. Couldn’t find anyone interested in making repair.
We bit the bullet and had a nee 6000 watt installed.
If anyone reading this is interested in making the repairs of which I have no idea what is wrong. I will sell the Cummins/Onan 5500 watt for the $2,500 plus Shipping! we are in it for parts and labor. I will provide a list of all the parts replaced buy a diesel technician (not an electrical repair technician)
Mike N Sherri Root
Saint George Utah