Diesel question

[KennyG]

My Kubota 7040 manual says to not operate at full RPM for first 50 hours. It uses about a half a quart of oil per 10 hours even up until now at 86 hours. I've gradually been working it harder and harder trying to seat the rings. I'm going to work the snot out of it for about 12 hours straight this weekend with an 8ft bushhog and see if oil consumption improves.

Also interested in the result. This would worry me a lot. I haven't seen any oil usage during break-in on either gas or diesel engines in the last 20 years or so. My impression is that manufacturing is so much better now that you don't have to be too worried during break-in.

 

[dieselcrawler]

I ran my 3005 easy for the first 3-4 hours then hit the field with the brush hog a full throttle. Doesn't use any oil, up to 113 hours now. I varry the throttle according to usage needs, mid-throttle for light loader work and box blade, brush hog takes all its got at wide open.

 

[PoorPlowboy]

Ill be interested in the result. You are still using dino oil right?

Yes. Kubota branded, specifically. I decided to use OEM oil until consumption disappears so there is no arguing if I have to press the issue. I have a good dealer that is aware of my situation and will make sure it's taken care of before the warranty expires.

 

[Arc weld]

Diesels are made to work. Some diesels will slobber or even get glazed up from continual low RPM. When working you don't need to be full throttle but there's a reason PTO speed is usually obtained at 3/4 or better throttle. If you want to putz around, get a gas tractor. Diesels are most efficient at higher throttle.

 

[brown40]

I think some of the concern is related to the torque curve of your particular unit. Run it just at peak torque RPM and the motor immediately gets "weaker" when the engine gets bogged by the attachment/duty. Run above the peak of the curve and the motor gets "stronger" as it gets pulled to the peak; run below the peak and the less than 100% motor weakens faster.
If you have a good sense of the task at hand and know nothing is going to try and drag back the rpms, there's no reason not to run lower, but for unknown contingencies, the motor having greater resources when the challenge is presented protects it from lugging. I try to keep at least 200-400 rpm above the peak (1750 for the yanmar) to have extra waiting if it's needed when I'm unsure. For PTO I run within 80-85% PTO speed at least so the attachment has more momentum working for it, even if the task could be done at 60%.
The beauty of the diesel is that they're typically rated for continuous PTO speed operation (usually at lower rpm's than gassers) without undue strain, heat, etc. creating problems... only more noise & fuel consumption. If you aren't lugging it, you aren't hurting it.

 

[fishheadbob]

It all depends. I rarely run the 50 hp anywhere near PTO speed unless I'm really needing full hp like when pulling a baler and full kicker wagon. Skidding too many logs, maybe. Mowing, snow plowing, running the woodsplitter, backfilling, never; more like 1000 rpm.I've had it for maybe 18 trouble free years. BTW, I'm half deaf anyway.
The little Deere has far less lugging power and needs to run in a higher rpm range to avoid bogging out.
I had a partner who loved to run in 2nd gear at 2000 rpm to travel from here to there; he had a strong aversion to doing the same thing in 8th gear at 900 rpm. Drove me nuts.
The manufacturers used to have a slogan I took to heart "Gear up and throttle down."

 

[Gary Fowler]

Which OEM and what year? 2009 Kubota? 2010 LS? /edit - my 98 M4700 says do not operate at full speed for the first 50 hours.
On my TDI I did about what you did, occasional full speed to set the rings.

THE LS, I bought new, the Kubota had 60 hours on it when I bought it and was already broken in. You may note that I said up to 2200 which is 300 less RPM than full throttle

 

[Gary Fowler]

My Kubota 7040 manual says to not operate at full RPM for first 50 hours. It uses about a half a quart of oil per 10 hours even up until now at 86 hours. I've gradually been working it harder and harder trying to seat the rings. I'm going to work the snot out of it for about 12 hours straight this weekend with an 8ft bushhog and see if oil consumption improves.

I would say that you babied it too much during break in period. It needs some hard work, not necessarily at full throttle but something to put some back force on the pistons for the rings to wear in tight. They might still seat if you load the engine heavy and then vary the throttle up and down from say near full throttle to about half and then back to full. Do this up and down at about 3-5 minute intervals for at least an hour, run it at PTO speed for an hour then do the variable speed again. If at the end of the day the rings haven't seated, they aren't going to.

Your oil consumption is almost typical of tractors from 40 years ago. Most diesel tractors of that era would use a quart or two per day when heavily loaded as with ground engaging activities that put the load at max.

 

[Topher265]

Running diesels at low throttle for long periods can allow carbon buildup. To avoid that, periodically run the engine harder at higher rpms.

 

[tman1020]

My manual states to run at least at 2200 rpm's but this is to allow the hydrostat to develop ample power. I still only run about 1800 RPMs for most tasks.