I found an Onan CMQD 7500 Quiet Diesel with 1340 hours on it in a rolled over semi at a local salvage yard. It appears to be OK but have not had a chance to load test it. Includes the remote panel for inside the vehicle. It's a CMQD 7500 7.5HDKAT41934K and I'm not sure what the difference is between this and the RV models.
How should I go about testing it? I need a variety of loads to put it through its paces. They want $2,500.00 for it. Seems like a good deal to me but I've seen posts about trouble shooting these Onans and who knows what might have happened to it in the rollover.
Fred
If it will start and run 2 roof tops it will power anything ;D
I've had two quiet diesels, both threw a chunk off of the rotor, at that point it's more expensive to fix than it's worth. I now have two perfectly good Kabota diesels with relatively low hours that I'm going to use for something else.
My 7500 QD has 2300 trouble free hours on it and still going strong.>>>Dan
They do throw the magnets off and will destroy the head I had to replace mine because of that, the magnets are just glued on the rotor, Cummins said it was bad glue sorry but we can't help you
If the 7500 is like my 8000 and I think it is, there are two 110v outputs on it. I would be sure to test both outputs. They do not make 220v when used together. They are separate circuits if that makes since. I have 1300 hours on mine. I had to replace a sensor once but otherwise it has been great.
Assuming that the generator wasn't running when the tractor rolled over, and assuming that there isn't any physical damage to the unit, I would think that it would work fine. I would pull the glow plugs out and turn the engine over by hand to see if oil got into the cylinders. If no oil comes out, crank it over with the starter (glows still out). If no oil still, re-install the glows and start it up. Remember to check the coolant level, and the air cleaner for oil.
$2500 is a really good price if it runs. The only problem with a Onan QD I've personally seen was one with a few hundred hours on it shutting off on overheat protection. The owner was cursing it up and down, mumbling all sorts of things.
You might want to price a replacement rotor and stator, just in case it goes the way that Clifford's and somewhereinusa's went. Just for reference, a new gen head for my Westerbeke is $3800 and only $1250 for my 20kw Generac industrial generator (4 cylinder Mitsubishi propane/NG engine).
Cummins charged me $3845.99 for the head ended up with labor costing $5248.00 and only took 6 weeks ;D
Quote from: luvrbus on February 10, 2015, 05:04:35 AM
Cummins charged me $3845.99 for the head ended up with labor costing $5248.00 and only took 6 weeks ;D
Ouch! Looks like you got my usual "discount" of List plus 100%, plus tax. It's a special club.... welcome.
Just remember that the generator is variable speed. That might make for fitful sleeping on a hot night everytime the A/C kicks on, the generator speeds up. Good Luck, TomC
Quote from: TomC on February 10, 2015, 07:41:21 AMJust remember that the generator is variable speed. That might make for fitful sleeping on a hot night everytime the A/C kicks on, the generator speeds up. Good Luck, TomC
I specifically bought my 8K "old technology" non-inverter type Onan diesel generator for that reason. I bought it in late '11, installed it in early '12 and have used it since. Do the loose magnets happen to the older-style, steady-rpm models???
It does tick you off Cummins knew about the problem as far back as the late 90's but offered no help or a recall
Is it possible that Cummins or another source would be able to say what years of manufacture had that issue so you could know what to avoid or upgrade?
Maybe a dealer like Dave here on the board would but you won't get any info from Cummins,I heard anything past 2003 was good to go you just fight the control boards going bad after that
I looked at that generator today. It is a CQMD 7500 HDKAT all right. The case has rust spots on it. I took the outside housing off. It's a 2006 model according to serial number lookup and the hour meter says 1324. Could it have 13,240 hours on it? 1324 in nine years is 174 hours a year on a generator mounted on a semi tractor. It's real dirty inside under the cover, the generator head is all rusty. I also turned the motor over by hand by turning the cooling fan to see if the cylinders had oil in them. The motor turned real easy; I didn't detect one compression stroke. Does a Kubota D722 have a compression release for starting that would make it that easy to turn?
Also the wires are broken off the electric throttle coil stator (on the injection pump) so that would need replacing. I'm starting to think this thing might be about worn out and might be why the owners left it behind when they crashed the truck.
Things that make me go "hmmmmmmmm"
Kubota engines don't have compression when turning by hand they need 250 rpm to even test the little jokers that is why they have glow plugs
Just a little update for you guys interested. Gumpy and I tested the generator by bringing a battery, fuel and resistive loads. While it sat on a pallet at the junkyard, we put it through its paces. And it seems to work fine. I gave them $2,000.00 for it and took it home. I removed the cabinet and am replacing all the hoses and that throttle control stator and the coolant overflow bottle. Hoses just because I can, the other two pieces because they were broken in the crash. We'll clean it up and paint it before installing.
I ran it quite a bit over the weekend with varying loads. Seems like we may have lucked out on this deal. Also, it included an EC-30 Remote control included in the package so I think I'm getting additional functionality from the EC-30 that I hadn't even anticipated.
Thanks for all the input.
You sure got a good price. Is it turns out to be a wonderful piece of equipment, you killed it. Even if it isn't *completely* wonderful, the balance is in your favor. Good job.
At that price you can afford to another grand into it and still feel like you got a good deal!
Fred,
For what it's worth, please replace the drive belt on the water pump... It will be a PITA later if
you have it installed.. An Onan belt will only fit it. It's about 45 bucks but it's metric size and hard
to find on the road. It happened to me and I replaced it with one from napa and it wouldn't work
so I had to do the job twice. Just about the whole enclosure needs to be removed to replace.
Good Luck
Nick-
Nick that's one of the parts that I'm replacing. As you said it is buried up against the side of the cabinet. I can see everything currently with the cabinet removed. I'm hoping to put it all back together, hide it in the bay and only do oil changes. The local Cummins dealer had that one in stock. They had to order all the hoses and the electric stator throttle control.
I learned from my cousin the diesel engine designer that three cylinder and six cylinder in-line engines are the smoothest running because the crank journals are 60 degrees from each other. Not sure what that means but I guess its smoother than a four cylinder or a V style engine.
Fred
Quote from: Fredward on February 18, 2015, 07:25:30 PM
I learned from my cousin the diesel engine designer that three cylinder and six cylinder in-line engines are the smoothest running because the crank journals are 60 degrees from each other. Not sure what that means but I guess its smoother than a four cylinder or a V style engine.
Fred -That means that every 120
os of crankshaft rotation produces a power pulse on the three cylinder models, and every 60
os on a six cylinder. On 4s and V8s, it's either 90
o or 45
o power pulse points, which sets up balance harmonics. Think of a round clock. On a three, you'll get power pulses at four, eight and twelve. On a four, your power pulses will be at three, six, nine and twelve. See how they're firing opposite each other on the four? That's where the harmonic vibration comes into play.
Looks like you got a good deal, that's for sure!
Quote from: OneLapper on February 09, 2015, 04:46:31 PM
The only problem with a Onan QD I've personally seen was one with a few hundred hours on it shutting off on overheat protection. The owner was cursing it up and down, mumbling all sorts of things.
Mark -Hmmmm. . . That sounds familiar! :-[
FWIW & HTH. . .
;)
Most 3 cylinders engines fire 1-2-3 in simple terms
Be advised,, these generators are VERY SENSITIVE about being shut down while under load,, always remove as many loads as possible BEFORE shutting down,,a $1400. bill you won't soon forget.....Don't ask how I know..>>>Dan
Dan,
Thanks for the warning. I have heard that elsewhere as well. I'm a major fan of removing load and letting any piece of machinery cool down for a few minutes before shut down. So I plan to treat this machine the same way!
Fred
It is also a learning curve for the wife & kids that may not understand.>>>Dan
On the Onan/Cummins Gensets, if you have one and need the parts manual or service manual, no problem, just provide the model, spec including the letter and serial number, can email info. Wrong / missing info = 0 results.
Have been an Onan dealer for 40+ yrs, love most models, not all and yes the magnets on some inverter models have been known to be an issue, my brother has the 12-18 kw model, and yes it also had to have repairs due to the magnets.
Were able to get some consideration on warranty, was out of warranty, but got about half covered, parts only, no labor warranty.
No noise from the variable speed genset, it is 35' from bedroom and very smooth & quiet.
Dave M
I've posted this before but it bears repeating. SmokStak.com is an incredible resource for old Onans. Here's a link (http://www.smokstak.com/forum/forumdisplay.php?f=1) to the Onan generator forum.
Hey Dave,
Thanks for the reply. It is amazing how nice and quiet they run. I have the cabinet off right now replacing anything that looks suspect. I discovered that the DC filter circuit board where the battery connections come through the case is broken. Rather the positive connection came loose from the circuit board. Do you know if I need to replace that item (300-4884) or will I get noise back somewhere through the 12 volt systems if I just run without it? I don't want to spend money needlessly but this is the time to replace it if it has a benefit.
Also do you have any experience with units that have the EC30 AGS that you could share? I've never had anything that fancy, but can envision using that functionality for maintaining house battery voltage when dry camping.
Fred
I have the wireless version of the command EC 30 I like the AC start up when the set temperature is exceeded what I don't like is when you disconnect from shore power and the generator starts lol
I haven't figured that one out yet then the auto start doesn't work while driving It's a neat gizmo Fred once you figure it out I have most of it figured out like the quite time that took me awhile
We have had the Onan 7.5 and have the Kabota 12.5. So wish we had the Onan back. It had plenty of power for us, used less fuel, and was a lot quiter.
Don and Cary
A 7.5 won't handle 3 roof tops in the AZ heat they struggle with 2 roof tops here in Aug