Onan diesel generator

[coolya]

Hello,
I have a 10kw Onan HDKAG generator powered by a 4 cylinder kubota diesel engine with approximately 3400 hrs.

The unit starts fine and runs strong, but there’s a very noticeable black haze when at or over 80% load. The exhaust temperature also seems to get very hot and the paint on the exhaust is starting to burn.

Not sure if it's a big issue, but I did research online and everything seems to be pointing to over-fueling. I've tried adjusting the fuel delivery underload and the unit stops hazing but then loses power.

Can anyone think of anything else?

Thanks!

[Jim Rankin]

air filter restriction or if turbocharged, you could have an exhaust leak dropping the boost a little, turbocharger failing, but they usually loose a lot of oil down the exhaust. Any of these would increase EGT and increase soot in the exhaust due to less "excess air" . It could be perfectly normal also, diesels get very hot exhaust and usually paint will not stay on the manifolds at least on the ones I see most often.

[coolya]

The unit is naturally aspirated. I've changed the air and fuel filter with no positive results.

I wish I knew how much exhaust soot is acceptable in a kubota.

Thanks!

[BTPost]

Just what did you adjust on the diesel to try and fix the problem? Usually
this type of problem is only resolved by Flow Benching the Injector Pump,
and the Injectors, as they are what regulates the fuel flow in a diesel engine.
If it is NA, then I suspect Injectors or Injection Pump problems.......Black
Smoke on a diesel at 80% load, is not normal for Kabota engines.

Bruce in alaska

[J. McNugget]

We have an HDKAG with over 10,000 hours on it - a pusher fan model. Ours does not smoke black - a little white on startup, but a pittance compared to my DJC.

If you have 3,400 hours on it and the paint is still on the exhaust, I think the engine probably needs a good, 90% load for 4-6 hours to clean it out. It doesn't seem like it has worked hard enough yet, and your 80% load is moving it into the "working hard" threshold.

We frequently trip the breaker in ours with the loads we subject it to. Load it up and let it run. Make sure you are using a quality brand of 15 W-40 oil too.
John

[pnora]

Before you waste any money you should read the actual exhaust temperature. This can be done with a hand held pyrometer gun. You can read the manifold at each port to determine if one or all are getting to hot. As said if the paint is not burned off it most likely has never been run under a load for a length of time. A diesel may seem to smoke because it is burning up all the soot and carbon. You also could install a pyrometer like an autometer in the manifold collectorhere all the cylinders meet and then you will be able to constantly monitor it.

[Elden DuRand]

Originally Posted by coolya

Hello,
I have a 10kw Onan HDKAG generator powered by a 4 cylinder kubota diesel engine with approximately 3400 hrs.

The unit starts fine and runs strong, but there’s a very noticeable black haze when at or over 80% load. The exhaust temperature also seems to get very hot and the paint on the exhaust is starting to burn.

I had an '82 Isuzu Diesel pickup that I converted to a Class C camper. Initially, it smoked A LOT!

I tapped the exhaust manifold and installed a pyrometer and boy, was I surprised at what I found out! At heavy load (not firewalled), the gauge would peg at 1,500 degrees F! By that point, it was smoking like crazy.

My solution was to design a Rajay turbocharger setup, including making both manifolds. With the turbo setup, it would just touch 1,500 degrees after a really long hill. Most pulls would see it peak around 1,200 to 1300 degrees. Peak manifold pressure was close to 18 PSI.

I got much less smoke and a little more power. I did NOT modify the injection pump. It was interesting to note that after I put the turbo on, the oil temperature ran higher. I suppose that was because since more of the fuel was burning in the combustion chamber, not going past the exhaust valves, the pistons got hotter, heating the oil.

It had almost 120,000 miles on it when we traded it and was still running fine. I always wonder if it would have lasted without the turbo. Lots of smoke and red-hot valves doesn't strike me as a good way to make an engine last.

Take care - Elden

[J. McNugget]

Sounds like a good result Elden. The oil would run hotter because you would have had an oil line running to the turbo to lubricate the turbine bearings. Lots of heat in those little things.

Any word on loading it up or pyro testing the exhaust, coolya?

[Steve Dawkins]

Hi Guys, please pardon the interruption. I'm curious what model Kubota engine is on the HDKAG genset? I have a Kubota V1505 4 cylinder diesel engine on a 12.5 kW genset, and was wondering if Cummins/Onan used that same engine on their 10 kW unit. Thanks.

[J. McNugget]

Hi Steve - the .pdf spec sheet I have for our unit lists the engine as the 1.339 litre size of the 05 family: D1305.

It was used in the 8 and 10 kW HDKAG series machines apparently.

I think the new Lincoln Vantage 300 welder uses the V 1505. I was looking at one of those, but it is not in the cards right now.

John

[Steve Dawkins]

John, thanks for the reply.

Steve