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Open Roads Forum  >  Class A Motorhomes

 > 7500KW Onan Quiet Diesel, code "33" over heat! ??

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Lake Havasu City AZ

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Posted: 07/25/12 12:05am Link  |  Print  |  Notify Moderator

Ladies and gents,
We're on the first leg/few days of our N. CA trip and near Bishop and was using our 7500KW Onan Quiet Diesel Gen to run the basement air. Well, we've owned the coach now for just over 15 months and the gennie's always operated just fine. It powers up the basement air with ease.
Well, we lit it off, turned on the basement air and just about the time the air started getting cool coming out of the vents, ZAP, the genny up and died. That's the first time it's ever done that. Well, I pushed the start button and it lit right off. And again, just as the A/C was starting to get cold, ZAP, the genny quit.

Well, this was repeated several times. Each time it would re-start without issue. But, it would only run around one to three minutes and then shut down. A buddy arrived and together we started checking things out. One the start switch on the genny itself, is a light it toggle. That toggle light glows red while the genny is running.

Now, the DW got the books to the genny out while we pondered where to start the analyzing. She started talking about codes and, how they're displayed. Well, when ours quits, that little light on the toggle will flash, three times, then three times again, and then a pause. Then it will do the same pattern again and again. Well, that means it's three and three which in super technical terms, code "33".

So, looking that up in the book, it's telling us that the genny is over heating and self shutting down. Now, you can stick your finger in the coolant overflow tank and it's barely lukewarm. I crawled under it and looked into the air intake area and the fan is clear with no debris obstruction what so ever. The part of the radiator I can see, it perfectly clear with no blockage what so ever. The radiator hoses look to be in great shape with no kinks and or weird spots of any sort. I do have an infra red heat gun and while point it at the top (I think it's the top) radiator tank, it's starts to rise over about 205 and ZAP, the genny dies. That, I think is telling me the thermostat is opening, not sure.

My son, who works for an RV service center in San Diego is saying it's highly possible for a bad sensor to tell the genny it's too hot and to shut down when in fact, it's operating temp IS quite normal. But, I've got no way of analyzing that sensor.

The level in the overflow tank is spot on. The air flow throughout the system seems to be perfect. There's a ton of air flowing in and really hot air coming out the back side. We did not try running the genny without any load, so that may or may not have any effect. As stated, we've ran that genny for well over 45 hours (not all at one time) and powered up all kinds of appliances at once and it's never skipped a beat.

We've got a copy of the service manual and code trouble shooting and will start working on part of the possible remedies. But, like many posts here on RV.net, I'd like to know if anyones had the same code and, what may have been the remedy in your case. Thanks for your assistance here. Very much appreciated.
Scott



Scott and Karla
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2004 Itasca Horizon, 36GD Slate Blue 330 CAT
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Smitty77

San Diego

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Posted: 07/25/12 06:29am Link  |  Print  |  Notify Moderator

It's Bishop! We had our QD8000 running for about an hour, and it too shut down in Bishop.

Waited an hour, and started it up again and ran one AC unit without a problem. Rest of the trip all went well.

I suspect my unit was hot, and shut down as it felt it should. With yours being still cool, I agree with the bad sensor thought. We did have the same code 14 months ago, and that was our problem then.

Reno is suppose to have some good shops...

Best of luck, be good, still have fun,
Smitty

Popsie

Livingston, TX, USA

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Posted: 07/25/12 07:16am Link  |  Print  |  Notify Moderator

There is no 33 fault

When it blinks 3 3, you have to push the button again, and it will give you a two digit fault code such as blink-blink-blink pause blink-blink-blink-blink-blink-blink which would be code 36. Code 36 could be a clogged air filter or fuel filter.

jones4110

Champlin, MN

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Posted: 07/25/12 07:44am Link  |  Print  |  Notify Moderator

I assume the oil level is acceptable.


Joan and Bruce
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...and a "road dog" named Max and his gabby sister, Abby.
"May the wind be always at your back and your destination the one you chose"


zmotorsports

Utah

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Posted: 07/25/12 07:54am Link  |  Print  |  Notify Moderator

Just out of curiosity, what elevation are you operating at?

A buddy of mine had a similar issue in his 2003 Journey a few years ago. When up archery hunting and running the A/C the generator would shut down or he would continually trip his overload circuit breaker on the generator.

I ran it at my shop for several hours without incident. He took it again for a family outing a few weeks later and called me because it had done the same thing.

After thinking about it for a bit I called him back and asked what elevation he was at. Come to find out he was just under 10k feet elevation.

There is a ~3% power loss per thousand feet elevation. So he didn't have a 7500 watt generator at 10k', he only had about a 5300 watt generator. His A/C was drawing more current than the generator could provide taking the power loss into consideration.

Just a thought.

Mike.


2003 Monaco Dynasty/ 26' Haulmark Edge trailer
2011 Jeep Unlimited Rubicon


Smitty77

San Diego

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Posted: 07/25/12 08:01am Link  |  Print  |  Notify Moderator

I'll check my notes on thr error code...

When we got into the generator, we found our belt was in bad shape so replaced it too.

Any chance your belt is broken?
Smitty

zmotorsports

Utah

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Posted: 07/25/12 08:43am Link  |  Print  |  Notify Moderator

Gsmitty77 wrote:

I'll check my notes on thr error code...

When we got into the generator, we found our belt was in bad shape so replaced it too.

Any chance your belt is broken?
Smitty


I thought about that as well but he said he had good air flow over the radiator. When I performed the 3k hour service on our Onan 10k Quiet Diesel the belt was in very bad shape.

I don't know how many hours are on Scott's genset.

Mike.

catallison777

West Columbia, South Carolina

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Posted: 07/25/12 08:58am Link  |  Print  |  Notify Moderator

My 7.5 did the exact same thing. It turned out to be the temp sensor. This is pretty common on the 7.5 quiet diesel. Its only about a $17 part.


2003 Damon Ultrasport 3873
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CA Traveler

The Western States

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Posted: 07/25/12 09:07am Link  |  Print  |  Notify Moderator

I agree that you need to get the second level fault code. The 33 code is telling you to do exactly that. And for possible confusion my QD7500 manual shows a second level fault of 33 which is over temperature. But make sure you get the second level fault code.


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Bob


Popsie

Livingston, TX, USA

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Posted: 07/25/12 10:17am Link  |  Print  |  Notify Moderator

CA Traveler wrote:

I agree that you need to get the second level fault code. The 33 code is telling you to do exactly that. And for possible confusion my QD7500 manual shows a second level fault of 33 which is over temperature. But make sure you get the second level fault code.
My Cummins Onan Operator Manual for QD7500 HDKCA/HDKCB says specifically that there are no 33 or 44 fault codes to avoid confusion with the initial blinking signal. Yours must be different.

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