proper operating RPM

[troverman]

Kubota CUT/SCUT diesel engines, like light truck diesel engines and CUT/SCUT engines manufactured by others, are throw away designs, not intended to be rebuilt except in unusual circumstances. They are not Detroits or even 50 year old JDs. They will not go 30K hours. In typical CUT/SCUT service, most will not go 10K hours.

This is not intended to be condemnation of such engines, Kubota or otherwise, as such designs are appropriate and cost effective for such applications.

SDT

This is an outrageous statement. Define "throw away" engine vs one that is not.

When there are Kubota small diesels (D series or V series) running without any type of rebuild or major work with 20k+ hours, that is not a throw away design. Nor are light truck diesels...there are plenty of untouched Cummins, Powerstroke, and Duramax engines with 400-500k miles on them. Heck, there are 12V Cummins engines with 1M miles on them.

And you can absolutely rebuild a Kubota engine. There are videos online showing it done.

 

[SDT]

This is an outrageous statement. Define "throw away" engine vs one that is not.

When there are Kubota small diesels (D series or V series) running without any type of rebuild or major work with 20k+ hours, that is not a throw away design. Nor are light truck diesels...there are plenty of untouched Cummins, Powerstroke, and Duramax engines with 400-500k miles on them. Heck, there are 12V Cummins engines with 1M miles on them.

And you can absolutely rebuild a Kubota engine. There are videos online showing it done.

A "throw away" engine is an engine not designed for repetitive rebuilds when worn out. This is well known by one skilled in the art and is certainly not an "outrageous statement."

Re read my earlier post. No where did I say that Kubota engines cannot be rebuilt. Of course, throw away designs can be rebuilt but such engines are designed and built for applications where rebuilding is not customary, e.g., automotive, light truck, modern CUTS/SCUTS, etc.

How many automotive, light truck, CUT/SCUT engines have you seen that do not utilize parent bore blocks, 3-ring pistons, etc?

SDT

 

[troverman]

"Throw-away" certainly has a negative connotation, don't you think? I classify it as an outrageous statement because it implies it won't last long, yet the engines in these tractors will likely last a lifetime.

A 'throw away' engine is what you buy at Harbor Freight. Very few applications need to have their engine repeatedly re-built because few engines have such constant use. I assume your referring to Class 8 trucks which put on a million miles. It is worth rebuilding simply because the overall cost of the vehicle and engine are higher.

 

[SDT]

"Throw-away" certainly has a negative connotation, don't you think? I classify it as an outrageous statement because it implies it won't last long, yet the engines in these tractors will likely last a lifetime.

A 'throw away' engine is what you buy at Harbor Freight. Very few applications need to have their engine repeatedly re-built because few engines have such constant use. I assume your referring to Class 8 trucks which put on a million miles. It is worth rebuilding simply because the overall cost of the vehicle and engine are higher.

It does have a negative connotation but such is inferred, rather than implied, and I did not coin the phrase.

The phrase is not descriptive of durability but, rather, application.

Few CUT/SCUT engines are rebuilt after 10K+ hours because it is likely that the HST and rest of the tractor are well worn as well, rendering rebuilding not cost effective. Hence, "throw away."

SDT

 

[Patt Swilling]

What about HST models? I thought you had to run them at a high throttle to keep the hydro working properly? I own a gear drive model but have heard this concerning HST's

 

[85Hokie]

What about HST models? I thought you had to run them at a high throttle to keep the hydro working properly? I own a gear drive model but have heard this concerning HST's

Patt,

you are a little late to the party - this topic kinda slowed 2.5 years ago.

The hydraulics DO run better/smoother when pushed up the throttle scale - DEPENDING on the engine, that RPM will be entirely different. I have 4 HST tractors that do not do well at a little above idle. I find that hydraulic work the best when the engine runs in that sweet spot .....up there in the zone - not putting around at idle.

The only time I back off the throttle is when I am in a tight place with my hoe - the swing on the BX25 can place a nice dent in something if not slowed a bit.

 

[Patt Swilling]

Patt,

you are a little late to the party - this topic kinda slowed 2.5 years ago.

The hydraulics DO run better/smoother when pushed up the throttle scale - DEPENDING on the engine, that RPM will be entirely different. I have 4 HST tractors that do not do well at a little above idle. I find that hydraulic work the best when the engine runs in that sweet spot .....up there in the zone - not putting around at idle.

The only time I back off the throttle is when I am in a tight place with my hoe - the swing on the BX25 can place a nice dent in something if not slowed a bit.

Yea I've only owned a tractor for about a year now

 

[RalphVa]

Driving a tractor comes back similarly to driving a car/truck with stick shift. You drive it with an engine speed such that you do not lug the engine. By lugging the engine, it does not have enough rpm to maintain enough oil pressure to keep all the bearing surfaces protected. Generally, on cars/trucks, this is about 1500 rpm, but it goes up to around 2000 rpm if one has a fairly small engine. (This was the case on a Fiat and Alfa Romeo we've had in the past.) On my Mazda3 with 2.5 liter engine, it actually does fine as low as 1300 rpm as long as it is on a level road or going downhill and not needing to accelerate very much. The Tacomas 4 cylinder (BIG one) does fine at 1500 rpm, as does my Miata.

Put more load on it, and you need more rpm because the bearings are put under more stress and need more protection of more oil flow/pressure.

My first tractor, a JD 4010, had a rated rpm of 3,000. I generally had to run it at around 2000-2200 for non PTO work (FEL, etc.) but ran it at 3,000 on the PTO because I needed all its 18.5 hp.

The last tractor I had was a JD 2025R rated at (I remember) 3,000 rpm at the "PTO" spot on the tachometer. Online, they say 3,200 now; maybe that's the gen. 2. I always ran it at 1800-2000 rpm for non PTO work and 2500 rpm on the PTO because I did not need all its 24.5 hp. When working the 2025R hard, I used more than 3,000 rpm for digging dirt or trying to pull a stump.

Current tractor is a B2601 rated at 2800 rpm. I run it at 1600-1800 on non PTO work and 2300-2400 on the PTO, again because I do not need all its 25.5 hp.

 

[B737]

Current tractor is a B2601 rated at 2800 rpm. I run it at 1600-1800 on non PTO work and 2300-2400 on the PTO, again because I do not need all its 25.5 hp.

 

[nbryan]

All the above. They are designed to be able to run WOT.
I assume you are talking about a MMM. My dealer told me to run the mower at full throttle, and I never had an issue.

Now the argument against reduced throttle: You always hear the argument that increased RPM's adds more cycles to the engine and will reduce life. But that is not necessarily a correct statement. If you reduce the throttle (and consequently RPM's) and you run into a situation that causes the engine to "lug" (reduce RPM's further), then you are doing more harm than good. That short period of time the engine was lugging caused more harm to your engine than if you had run it at WOT without lugging the engine. The point being... it is less likely to lug (detrimental to engine) at WOT than if you had reduced throttle/RPM's. Keep the RPM's up and you will have less issues with insufficient power... which is better cosidering the long view of engine life.

As an extreme example, my brothers neighbor has several pieces of diesel equipment. It is his hobby - he likes to work on them. But he keeps running them at idle thinking he is saving the engine life. So he is out working his skid steer at idle and he keeps over loading it and stalling the engine. For some reason he has got it in his head that what he doing is better for the engine than increasing the throttle. So he is constantly lugging the engine, and it gets to the point that he stalls out the engine several times when using it. That is hard on the engine, but he has less cycles on it... makes no sense.

Sent from my SM-J737V using Tapatalk

He likes to work on them? He'll be happy then, after all the lugging breaks down his engine and pumps.

 

[RalphVa]

My Op Manual says 22 hp for 2301 and 25.5 for the 2601

 

[RalphVa]

Ran a 240D Benz for 215k miles and 26 years at shift points to get at least 1500 rpm at the next gear. Was also good for the VW TDI, shift to get 1500 rpm. The Benz still ran virtually like new when we sold it. Just got tired of trying to make do with 65 hp.

Under much load, need at least 2000 rpm, and that's what I ran these at. Same for the 3 tractors.

You don't need to race them at rated rpm all the time. That's a waste of fuel and hp.

 

[BIGO]

I quit using my tractor, it was wearing my tires down

 

[B737]

nvm

 

[SinNH]

Ran a 240D Benz for 215k miles and 26 years at shift points to get at least 1500 rpm at the next gear. Was also good for the VW TDI, shift to get 1500 rpm. The Benz still ran virtually like new when we sold it. Just got tired of trying to make do with 65 hp.

Under much load, need at least 2000 rpm, and that's what I ran these at. Same for the 3 tractors.

You don't need to race them at rated rpm all the time. That's a waste of fuel and hp.

Haaa!
I had a buddy with a 240D, ( maybe a '72) beautiful auto, wicked underpowered, with five guys on board I don't think he ever got it out of third. Still see them around. still smoking.

 

[Mruysch]

My dads m7950dt has 12000 hours on it and 50% of its life it is run at the governor. The only thing that has been done since he bought it in 1993 is 3 clutches

 

[Deleted member 47704]

Good Works just put a vid on you tube about engine rpm.

 

[lynnmor]

Haaa!
I had a buddy with a 240D, ( maybe a '72) beautiful auto, wicked underpowered, with five guys on board I don't think he ever got it out of third. Still see them around. still smoking.

Years ago, I rode with a salesman all the way across the PA Turnpike, talk about slow, he had to look back to the next exit when coming down an on ramp. 60 some horsepower in an overpriced car like that is ridiculous.

 

[RalphVa]

Haaa!
I had a buddy with a 240D, ( maybe a '72) beautiful auto, wicked underpowered, with five guys on board I don't think he ever got it out of third. Still see them around. still smoking.

Would have been a 220D, only 55 hp. Had one of those before the 240D. Wife loved the 240D.

 

[RalphVa]

Years ago, I rode with a salesman all the way across the PA Turnpike, talk about slow, he had to look back to the next exit when coming down an on ramp. 60 some horsepower in an overpriced car like that is ridiculous.

The 240D wasn't particularly slow. If you tried to follow my wife in it with another car, you 'd have had trouble keeping up with her. It would go right up Afton Mountain to the west here as long as you could hold it above 60 or 65. Drop below that, and it'd down to 3rd gear and maximum of 55.

You could drive it all day long full throttle at around 80-85 mph and probably see about 28 mpg.

When speed limits were down around 55 mph, we'd be passing all the other cars on hills because most of them aren't geared to be going so slowly uphill such that they'd drop down in speed.