Kubota diesel engine life question - PeachParts Mercedes-Benz Forum

Motorhead · #1 12-01-2006, 09:17 PM

Any of you guys know how many hours a Kubota 3 cyl 850cc engine is good for?
I went and looked at a 6,000 watt 1800rpm Kubota powered generator today. I want it for power back-up for my house. The unit WAS in a towable light tower. It has 10,000 hours on it.
It runs well with NO blowby.
The guy is asking $900.00 for it.
It is an industrial made up unit, not a home made job.
He has it mounted, self contained, on a pipe skid with a 15-20 gallon fuel tank, battery, and engine control console.

So... Do any of you know about the engine life span in hours???

#2 12-01-2006, 10:23 PM

The company I work for has a Kubota D905 as a pony engine. It's got over 6,000hours and has never given us problems.

We DID have two. The other one died from a cracked head. It was not really the engines fault, the crew let the radiator plug with insulation that caused it to overheat. They elected to replace it with a 21hp Kohler V-twin. That terrible little thing has given us never ending problems and recently blew out it's piston rings.

$900 sounds a hair high. If it starts well and does not smoke, I'd haggle down to $850 and go for it.

Jeremy5848 · #3 12-01-2006, 10:32 PM

Let's say your Benz has averaged 40 MPH over its lifetime (pure guess on my part). Over 10,000 hours it will travel 400,000 miles. That's a lot. Be careful.

I have a Satoh (related to Mitsubishi) 'Beaver' tractor with a twin-cylinder, water-cooled, 669 cc, 13 HP at 2700 RPM diesel engine. These tractors do not have hour meters. Engine overhaul time is determined by either a compression test or an oil use test. "Good" compression is 455 lbs/in2 (32 kg/cm2) at 380 RPM; the service limit is 313 lbs/in2 (22 kg/cm2). Oil use limit is 150% of normal.

I also have an Onan 'gas-gaso' (runs on gasoline OR propane) engine, 2 cylinders air-cooled, 60 cu. in. (about 983 cc), 21.6 HP, running a 7500 Watt generator and using propane for fuel. The manual calls for a "complete reconditioning" every 5000 hours but does not define the term. However, it must be fairly serious, since they call for "grind valves" and "clean combustion chamber" every 1000 hours.

Maintenance is the key factor in any engine (especially oil changes). Try to get the owner to give you service records or at least tell you what kind of service has been done. I would be concerned that engines like this might be used hour upon hour with no service at all. Other owners might watch the hour meter like a hawk and follow the book religiously. You need to decide what kind of an owner you have there. A manual for that engine might also be nice to see. Get the model number of the engine and find a Kubota dealer or service place, see if they've ever heard of the thing, ask about parts availability.

Hope that helps. Good luck.
Jeremy

Motorhead · #4 12-01-2006, 11:10 PM

Yea, I wondered what kind of service the engine saw too. The one good thing is the guy worked on boats such as tug boats and motor-yacht types. I looked at his other equipment and it looked pretty good.
I would like to do a cold start on it as when I got there it was running. BUT, It had not been used in three years and was stored on a mesanine in his metal workshop and the time between me calling him and seeing it was about 40 minutes.

What I am really looking for is an engine service life guide to see what they really run.
I looked online at the KUBOTA site and the specs for the engine are 19hp@ 3000rpm but they also had a generator table that said that the engine put out 11hp@1800rpm. Alot less strain on the engine than running at full goverened speed.

vstech · #5 12-02-2006, 10:08 AM

kubota is one of the most widely used diesel powerplants in industrial machinery. 10,000 hours is a lot, do a compression test, and do a good blowby test, bearing in mind the crankcase is ventalated to the atmosphere on a lot of the motors. (you could be checking for blowby on the oil fill cover, while the crankcase vent is open) also realize the generator unit itself will need service, bearings, slip ring or brush updates. see if there are service records for the unit. the local to me Pep Boys has a nice 8KW 2 cyl Diesel generator on a cart for 1400.00 brand new.
It sounds like a very nice generator. I would not pay more than 400 for that small a unit that is that old. I am amazed that a 3 cyllinder diesel would be required for a 6KW unit. What voltage output is wired to the unit? some are phased at 460 or higher... bear that in mind.
JM.02
John

Jeremy5848 · #6 12-02-2006, 11:08 AM

I should have mentioned this in my earlier post. Good commercial generators new are expensive, like $10K and up. The fact that your seller is asking only $900 suggests that he at least suspects that the thing is pretty worn out. Caution is advised. You might get lucky, you might not.

Motorhead · #7 12-02-2006, 11:21 AM

Quote:

Originally Posted by vstech

I am amazed that a 3 cyllinder diesel would be required for a 6KW unit. What voltage output is wired to the unit? some are phased at 460 or higher... bear that in mind.
JM.02
John

John, I think that the reason they are using a 3 cyl is the fact that the generator runs at 1800rpm. The engine develops about 19hp at 3000rpm but at 1800rpm, it develops only 11hp. The generator was built in 1992. It is a 120/240volt unit single phase.

t walgamuth · #8 12-02-2006, 11:25 AM

so how many kw would i need to power my airstream? it has ac.

i have often thought it would be nice to have a little gen to run when i want to stop and sit so i dont have to run the dodge, you know, when not at a camp site.

it would have to be diesel.

tom w

Motorhead · #9 12-02-2006, 11:48 AM

Tom, If you have only one A/C unit, a 5k is ample. Onan makes diesel powered, covered units for large motorhomes. I have a 3.5k Makita open frame genset for my 28ft trailer. It will start and run the A/C with no problems and it is electric start.

I built an extended rear bumper/rack on my trailer to hold the generator and bycycles. I just pull out the trailer shore line and plug in to the genset. It is nice to have when traveling through HOT areas where you want to stop to rest or eat.

t walgamuth · #10 12-02-2006, 12:01 PM

cool. that is what i was thinking. but also i might want to stop at night while traveling, so diesel operation is essential as i dont want to risk carbon monoxide poisoning.

about ten years ago some folks from canada died the night before the indy 500 in their motorhome from it.

tom w

#11 12-02-2006, 01:21 PM

Quote:

Originally Posted by Motorhead

John, I think that the reason they are using a 3 cyl is the fact that the generator runs at 1800rpm. The engine develops about 19hp at 3000rpm but at 1800rpm, it develops only 11hp.

But at that speed it will be making about 30ft/lbs of torque. A gas engine would barely put out half of that.

kerry · #12 12-02-2006, 02:08 PM

I had a 4kw on my Travco which powerred one AC easily. My Wanderlodge has 3 AC'S and the generator is a 12.5KW driven by a 4 cyl Perkins 108 diesel. It's a 1982 and has about 650 hrs on it. 10,000 hrs sounds high to me.

Tom,
Why would diesel make any difference with carbon monoxide?

bgkast · #13 12-02-2006, 02:09 PM

Diesels create CO too. I just did a 14 page lab write up on CO if anybody is interested.

babymog · #14 12-02-2006, 02:26 PM

10k hours is a lot, but since good diesel powerplants go for around $1/wh a 6kw or 6kva plant is around $6k new with a warranty.

In dealing with 8kw to 15kw diesel plants in our Wanderlodges, it is usually not the engine that causes problems, the generator itself will, or the injection system, or regulation, etc. If the generator isn't a common make with lots of parts and service availability, it is a boat anchor at best.

The condition of the rotor and stator is important. Also, is it brushless? If not, when was it serviced? If it was used and not maintained well it will be pretty much toast.

Good luck,

t walgamuth · #15 12-02-2006, 03:19 PM

Quote:

Originally Posted by kerry edwards

I had a 4kw on my Travco which powerred one AC easily. My Wanderlodge has 3 AC'S and the generator is a 12.5KW driven by a 4 cyl Perkins 108 diesel. It's a 1982 and has about 650 hrs on it. 10,000 hrs sounds high to me.

Tom,
Why would diesel make any difference with carbon monoxide?

both gas and diesel make carbon dioxide, but a diesel makes almost no carbon monoxide. it would be almost impossible to die from breathing diesel fumes. (you will gag first.) a modern gas car in good operating condition is probably not going to kill you either but a gen will not have all those sophisticated emission controls, is it?

tom w