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Old 09-07-2013, 11:01 AM   #1
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Onan Diesel Generator Trouble

I have a model 7.5 HDKAJ Diesel generator in my 2000 Monaco Dynasty Coach. Serial number 990881546. I am having trouble keeping it running. It starts fine but runs blue smoke out of the exhaust then shuts down after less than 2 minutes and flashes code 3-3 which is "engine hot". There is no way that the engine is hot. I have removed the cover and found many magnet particles stuck to various metal surfaces. One large piece resembles part of an electric motor stator. It has less than 400 hours.

This looks very serious to me.
I have several questions.
1) Can you tell me what might be the problem?
2) What may have caused it?
3) How expensive will it be to repair?
4) Will it be possible to repair it myself?
5) Do you think I should scrap it and buy a new or used one?

Thanks,
Art Perrone
Sodus Point, NY
APerrone@excite.com
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Old 09-07-2013, 11:34 AM   #2
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A belated welcome , first post , I see.
Lack of use and internal rust, are the biggest killers of gen sets.
Onan, recommends 2 hrs. of exercise every month, and a lot of units never see that. If you have chunks of magnet floating around the generator portion is definitely in trouble, and would be available as a ; sub ; assembly. The blue exhaust smoke , and hot engine codes, may be an indicator of internal problems with the motor , or due to the extra load on the motor by a generator that wont rotate at full speed.
Cost ? Rebuild or replace ? DIY ?
Easiest would be replace, and new, would help avoid buying someone else's rusted unit. New would come with a warranty.
DIY. That depends on your skill level. Replacement , the units weight is a problem; but few tools involved; re-build , weight comes into play again and there may be a need for special tools once inside.
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Old 09-07-2013, 01:43 PM   #3
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Quote:
Originally Posted by APerrone View Post
I have a model 7.5 HDKAJ Diesel generator in my 2000 Monaco Dynasty Coach. Serial number 990881546. I am having trouble keeping it running. It starts fine but runs blue smoke out of the exhaust then shuts down after less than 2 minutes and flashes code 3-3 which is "engine hot". There is no way that the engine is hot. I have removed the cover and found many magnet particles stuck to various metal surfaces. One large piece resembles part of an electric motor stator. It has less than 400 hours.

This looks very serious to me.
I have several questions.
1) Can you tell me what might be the problem?
2) What may have caused it?
3) How expensive will it be to repair?
4) Will it be possible to repair it myself?
5) Do you think I should scrap it and buy a new or used one?

Thanks,
Art Perrone
Sodus Point, NY
APerrone@excite.com
APerrone,
Well Sir, I could have, and in fact did, write your exact thread, several months, or even a year ago. I had the EXACT same situation as you, Word for word, just about. First. let me say, tearing apart one of the Generators is not all that hard. If you've got any mechanical skills, some basic tools, and a camera, you're set. I say a "camera" because, I took a zillion pictures of everything that I thought this old brain of mine would not remember what it looked like before, during and after I started working on it. That included bracketry on the outside, what screws went where, different types of heads, anything that would jog the memory as I was putting things back together. One thing that will make the repair etc. a lot simpler would be if your generator is on a slide out tray. Otherwise, that part of it, getting it out to work on it can be a pain.

There are a couple of gents on here who've had to do it. There are SEVERAL on here and other RV forums that have had the same exact code. The infamous code "33" does stand for "Over heat condition" but, the truth of the matter is, about 99.99999% of the time, it's not an overheat condition.

You see, there's a "temperature sensor" located in the lower portion of the thermostat housing that, for the most part, is a $17.00 part but, can cause the owner to spend upwards of more than $1,500 by the time it's replaced. There are multiple reasons for the elevated cost. If you don't do the work yourself, and, you DON'T have a sliding tray, and, that sensor is "Frozen" into it's threads, all that means more hours of labor to do the correct repair. For some bizarre reason, that sensor has tendency to lock itself to the threads and becomes a serious pain in the a$$ to remove.

Much of the time, it has to be drilled, then, if there's any good portion of metal left in the housing, it can be re-tapped, then a new one installed. All of that takes time, and time is money. But, some of the owners are lucky and, that sensor comes right out. You see, what happens is, the tip of that sensor is cylindrical and, it has very little clearance between it and the thermostat housing that it's mounted in. And, even though you might have really good, clean coolant in that cooling system, the flow characteristics of that tight area around that sensor, do not allow for much flow and, what happens is, deposits start accumulating on the sensor tip.

As time goes on, the more and more deposits/corrosion grow on that sensor tip to the point that, it is now sealed and comes in contact with the "tunnel" that it normally resides in. Pretty soon it's SOLID. When that happens, the sensor starts sending out false signals. And, since much of the generator operation is based on what that sensor dictates, the gen can only react to what it's told, which, in your case and, several others, is not a true reading. So, long story short, yep, the sensor has to be replaced.

The Question is, can you do it yourself? Well, that, as stated, all depends on some of what I stated above. I'd be glad to coach you through the entire operation. Been there done that, as well as others on here.

Now, that's one problem. Your other problem is also identical to what I had. The "Magnet" pieces you're seeing stuck to any and all metallic surfaces inside that gen cabinet is, part of one of the rotor magnets. Onan had an issue with some of it's rotors back some time ago. Some, were caught in time and, under warranty and, the entire rotor was replaced. There are, I think, 8 magnets on that rotor. One of mine, just like yours, blew itself off the rotor and disintegrated into a zillion pieces all over the inside of the gen cabinet.

That rotor, is about $425.00, from Onan. I got extremely lucky at the exact time I was doing my repair, I cruised through ebay and found a rotor off of an 8000 watt unit that was in perfect condition and, the price, $200.00 and about $20.00 for shipping. I jumped on that like lightning.

Getting to the point where you can remove that rotor is some work. But, it's simply nuts and bolts. Well, actually it's more like quite a few screws. That entire generator is held together with almost nothing but screws, different types of heads, but, none the less, screws.

Anyway, that's what you're up against. I have a complete write up, like stated about a year ago almost to the month. I'll look it up if you'd like and send it to you or, you can dig around and find it. There's several pictures there too that will assist you in seeing what the inside of one of those gens looks like. Do not hesitate to ask.
Scott
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Old 09-07-2013, 05:46 PM   #4
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Thanks for the welcome and the important information you gave me. I am progressing toward a solution thanks to much advice from many members. I am going to talk more with Scott to see if I should attempt a fix myself, if not, I will wait until I travel south for the winter and look for a repair facility down there. Money is an issue, but so is a good job that will last.
Thanks again,
Art Perrone
APerrone@excite.com
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Old 12-13-2015, 09:32 AM   #5
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Were you able to find a manual for the 8000
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Old 01-21-2016, 04:57 PM   #6
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Yes, I found it on line but I can't remember where, sorry.
Also sorry for the late response.

Art Perrone
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Old 02-28-2016, 04:37 PM   #7
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Onan 8000 heat sensor broke off
To remove the thermostat housing

On the thermostat housing is the third bolt behind the water pump or does it share a bolt with the water pump
Any help is appreciated
2003 CC Intrigue
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Old 03-01-2016, 03:34 PM   #8
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I recently had an issue with a code 3-3 along with some others at various times. None of them appeared to be valid. It turns out that there is a bolt on the DS of the generator that provides a ground for almost every wire on the generator. That bolt wasn't even finger tight.

Bolt tightened, problem solved. Access is fairly easy if your generator is on a slide tray. You have to remove the top before you can remove the left side but you might be able to check it with just the top removed.
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