D1005 idle speed /rough idle?

[delcrest]

Hi, I have a small Kubota 3 cylinder engine (D1005) that that will only idle smoothly at about 1150 rpm, which is bit high for my application
At 1000rpm it almost seems that one injector is not getting fuel and very rough idle, adjust the idle speed up slowly and it suddenly idles perfectly
I am only adjusting the idle speed on the accelerator arm, is there any other adjustment that could be done to correct this. I would be very happy at an idle speed of about 850rpm,All else seems good making power very nicely
Thanks in advance for any comments and suggestions

 

[North Idaho Wolfman]

Hi, I have a small Kubota 3 cylinder engine (D1005) that that will only idle smoothly at about 1150 rpm, which is bit high for my application
At 1000rpm it almost seems that one injector is not getting fuel and very rough idle, adjust the idle speed up slowly and it suddenly idles perfectly
I am only adjusting the idle speed on the accelerator arm, is there any other adjustment that could be done to correct this. I would be very happy at an idle speed of about 850rpm,All else seems good making power very nicely
Thanks in advance for any comments and suggestions

No amount of adjustment is going to fix your issue, you'll need to have the injectors serviced or replaced.

 

[delcrest]

No amount of adjustment is going to fix your issue, you'll need to have the injectors serviced or replaced.

Hi thanks for your reply,i have this problem on two new "OUT THE BOX" engines on about 20 hrs running time on each, no agent that i can talk to here in darkest africa
There has to be some way of adjusting the idle speed lower.The importer i bought these engines from has now gone out of business
thanks
for comments and suggestions in advance

 

[eserv]

No amount of adjustment is going to fix your issue, you'll need to have the injectors serviced or replaced.

There might be a problem with injectors here but in my experience those engines will not idle smooth bellow 1100 rpm without much larger flywheels. About 10 years ago I experimented with a D1105 in a small car and the only way I could get an idle below 1000 was by bolting two flywheels together.

 

[delcrest]

Thanks for the reply,changing the rpm as little as 100 rpm will take the rough idle away,1100rpm very rough idle 1150rpm idle smooth, wondering if it is not the injectors maybe they are not "calibrated " for a low rpm,

 

[North Idaho Wolfman]

Eserv has a lot more hands on knowledge of these engines than I do, so I'm betting he's right, they just won't idle that low.

 

[delcrest]

The same engine is used by beta marine,with there marine exhaust system, this version seem to idle at 850rpm with no problem, Really hope i can solve the problem
thanks
for the comments

 

[eserv]

The same engine is used by beta marine,with there marine exhaust system, this version seem to idle at 850rpm with no problem, Really hope i can solve the problem
thanks
for the comments

Some variations of those engines have a injection timing advance mechanism. I believe that might improve the idle. I have never worked with one with the advance on it though.

 

[beex]

I don’t think that engine was designed to idle down that low. Not good for it.


Sent from my iPad using Tapatalk

 

[thepumpguysc]

if your "positive" about the 1 cylinder not putting out fuel.. have u swapped injectors to a different cylinder to see if the problem follows the injector.?

 

[delcrest]

if your "positive" about the 1 cylinder not putting out fuel.. have u swapped injectors to a different cylinder to see if the problem follows the injector.?

Hi no I am not positive, that was the best way to describe the vibration.
its just strange that it the same on two new engines that only have about 20 hrs each, low idle vibration was from day one out of the box first run

 

[thepumpguysc]

"positive" meaning as sure as one could be w/o measuring the delivery..
Can u loosen a line AT THE INJECTOR 1 @ a time & retighten & tell which one has the LEAST effect on the running condition.??
Once u find it, either swap it w/ another from the same engine or go to the other engine & get 1..
MAYBE u can get 1 engine running smooth by swapping injectors & then have the "other set" rebuilt..??
Another thing that will cause a rough running engine is the torque on the deliver valve holders on the inj. pump.. IF they're loose, it'll cause all sorts of problems as u described..
Using the 2 wrench method.. hold the holder ON THE PUMP & loosen & remove the steel line going to the injector..
CHECK the torque on the holders.. it should be 30-35 FT LBS.. no more-no less..
Good luck.

 

[delcrest]

Thanks for the reply, will be back at the engines next week and give that a try

 

[Dave_eng]

I have found using an cheap infrared temp gun pointed at each cylinders exhaust port quickly tells you if the cylinders are working uniformly or not.

The cylinder not working as hard as the other(s) will have a significantly lower exhaust temp.

Dave

 

[GeoHorn]

I have a Kubota RTV-X900 with one of their small 3-cylinder diesels and it idles “rough” also if idle is adjusted down to what other diesels like. By increasing the idle speed to a point just-above the rough idle it does really fine.
Since the “accelerator” pedal on the RTV actually is tied to both throttle and HST, the idle speed does not affect the drivability of the vehicle. A small press on the “accelerator” pedal merely places a small request to the HST to move. Further advance of the pedal adds both HST motive force as well as adds engine speed.
Attempts to get these small diesels to idle at low speeds such as experienced with larger diesels will result in excessive vibration which breaks brackets, mufflers, welds, and associated items.
I suggest you adjust your idle up to a point of smoothness and live with that, in the comfort that you are preventing other failures. The addt’l fuel consumption is negligible.

 

[delcrest]

I have a Kubota RTV-X900 with one of their small 3-cylinder diesels and it idles “rough” also if idle is adjusted down to what other diesels like. By increasing the idle speed to a point just-above the rough idle it does really fine.
Since the “accelerator” pedal on the RTV actually is tied to both throttle and HST, the idle speed does not affect the drivability of the vehicle. A small press on the “accelerator” pedal merely places a small request to the HST to move. Further advance of the pedal adds both HST motive force as well as adds engine speed.
Attempts to get these small diesels to idle at low speeds such as experienced with larger diesels will result in excessive vibration which breaks brackets, mufflers, welds, and associated items.
I suggest you adjust your idle up to a point of smoothness and live with that, in the comfort that you are preventing other failures. The addt’l fuel consumption is negligible.

Thanks for the sugestions, think that is what i am going to do, just didnt like going from neutral into gear and having the shift hard, its on a boat manual transmission ie damper plate only np clutch

 

[lugbolt]

3 cylinder engines have an inherent shake. Nothing you can do about it aside from completely redesigning the engine to use a counterbalancer. V6 engines have the same problem but most of those have intricate engine mounting systems (aka fluid filled mounts) AND counterbalancer mechanisms to get rid of their shake. A 3 cylinder DIESEL...with high compression (required for it to run) will shake twice as much as a 3 cylinder gas engine at the same low RPM, which is exactly why Kubota's super mini's all idle at 1100+. If you try to "turn the idle down", it is GOING to shake. On the ZD series (321/326/331/etc), if you idle one of those down "to normal level" (what people think should be normal, about 800 or below), the thing shakes so violently that it sounds like a miss AND parts of the engine become blurry because it's all rubber mounted and it shakes so violently. The only cure is a counterbalancer (redesign of the entire engine) and/or a flywheel that weighs 75 to 150 lbs and even then they aren't going to be as smooth as people expect them to be.

Think about why. A diesel engine's power stroke causes a rapid acceleration of the crankshaft which causes the engine to "torque" (twist). A single cylinder diesel is one of the roughest running engines that I know of. A twin cylinder is better. A non counterbalanced 3 cylinder is a little better but now you introduce a second order harmonic vibration. With a 3 cylinder, you have a power stroke every 240 degrees of crank rotation. A power stroke only lasts maybe 90 degrees of crank rotation so the crankshaft is rapidly accelerated for approximately 90 degrees of rotation, then it begins to slow down UNLESS a big heavy flywheel is put on it, which slows the rate of acceleration AND deceleration, such that the speed of crank rotation is is "evened out" somewhat. The more cylinders there are at play the smoother running it becomes but a 3 cylinder diesel is always going to be a little rough.