Idle Speed...why so fast??

[Egon]

Does this Kubota 3 cylinder engine have a balance shaft?:thumbsup:

 

[leonz]

The whole mess has me a bit worried for the owners of the 3 cylinder prime movers due to the rattling etc.

Something is wrong somewhere and they are supposed to have a good quality control program for their engines and transmissions.

If thye are not using good motor isolation mounts the entire point is moot as the rotation of the crank and the flywheel are either adding or cancelling the centgrifugal force generated by the crank in the combustion cycle.


If anyone could post a picture of the following:

a. flywheel/v belt pulley

b. motor mounts and attachment points at all four positions in including the transmission under the BX or B units.


My other question is the transmission part of the rear trans axle or separate?




leon

 

[_RaT_]

My L3830 3 cylinder was very smooth at idle speed which I think was about 850 RPM, as smooth as my 5 cylinder L4850. My old International 454 3 cylinder was the smoothest diesel I have ever owned. It was also the dirtiest burning engine. Smelled like a BBQ after you lit the gas to get the charcoal going.

 

[kuboman]

The more cylinders you add the slower the idle can be and still be smooth. Degrees of crank rotation between power strokes determines the speed. Any engine will have a critical rpm where things are just 'wrong'. Find the right spot and any engine will idle smooth. Any 3 cylinders I have/had would idle smooth +/- 800 rpm.

 

[oldballs]

I hate to shut my BX2660 off. It shudders the whole machine for a second before actually quitting. It idles nicely at 1340 rpm and I ain't messing with it.

 

[kuboman]

I believe that all kubota tractors are bolted solid to the frame at least on the B and up series. There front mount lawn mowers are rubber mounted and it is hard to really tell much difference in the vibration. Find a idle speed you like and leave it there and be happy as none of these engines are going to be perfectly smooth at all rpm. A little vibration lets you know it is running:laughing:

 

[wowwee]

Well, thanks for all the discussion. I am going to try lowering the idle speed in a few weeks when I do the first fluid changes. I'll let you know how it turns out.

Dale

 

[wowwee]

Hi, I finally dug up this thread again.
I played with my minimum idle speed and the results were.....it was the best the way it came out of the factory, about 1200 RPM. Anything slower was too rough.

Thanks, Dale

 

[Transit]

Rswyn, never seen a Kubota engine, do they have one glow plug for each cylinder? If so, the run to keep warm is a load of horse apples. The key word is GLOW; the plug will be hot from the last ignition cycle to aid in firing the next charge.
Once the engine is running the glow plugs are ALWAYS on.

I cant show you the math, but the problem goes like this.
At a temperature of 1,100 deg F to cause the fuel to ignite for a given compression ratio, what is the minimum intake air temperature? Most diesels will start unaided to 45 deg F. and true, engine heat will lower that point while running.
Some of the technology of the Hot Bulb engine is incorporated in modern diesels to run in low temperatures.
The high idle may also cleanup the emissions.

Take a look at Hot Bulb engine, a diesel engine + glow plugs.

Hot bulb engine - Tractor & Construction Plant Wiki - The classic vehicle and machinery wiki

 

[leonz]

Hey There, I've got a 2008 model B2320. Once it's warmed up the lowest it will idle is about 1100 RPM. Anyone know if I will do any harm adjusting the speed a little lower? Maybe Kubota has to set it there from the factory just to meet emmisions standards?

Thanks, Dale

I suggest that you leave it alone as the vibration created at the low idle setting will simply increase the possibility of deveoping the dreaded vibration disease diagnosed originally in Japan and referrred to as wood cutters disease-(which occured when chain saws were first introduced in japan)
which is why chain saws now have vibration isolation withing thier frames and engine mounts.

The lower idle speed settings are why so many of the members are dealing with vibration and shake and potential nerve damage.