D1105 idles out of control

[Kubix]

Hi!

Im the owner of a Kubota KX41 mini excavator. Year 1996, 4600 hrs on the clock.
The Engine, a D1105, has a bit of an annoying Problem: whenever it warms up, the idle Speed rises out of control, as long as there is no load on the engine. When started cold, everything is fine, but as soon as the engine temp rises above the "cold" mark on the gauge, the rpms begin to rise, no matter what the throttle is set at- getting higher and higher with the rising temperature, until it tops out at 3000 rpm on the fully warmed engine.

As soon as a load is put on the engine (operating a hydraulic function), rpms drop back down and it runs nicely at whatever speed the throttle lever is set at. Remove the load, and the speed rises again, until a load is reapplied.

Otherwise, the engine runs fine. Has plenty of power, starts well even in the cold, doesn´t smoke or use excessive amounts of oil.

I´ve checked the governor springs, they are intact and correctly installed, and also played around with the injection pump settings- to no avail.

Anybody got an idea, why it does this? Google didn´t yield results. Any idea is greatly appreciated!


(And please bare with me- i´m not a native Speaker)

Greetings, Kubix

 

[RCW]

Kubix - Your message came across perfectly given the language issue.

I am NOT an authority for the problem you are having. My first thought while reading your message was governor/linkage also.

I'm dealing with a similar problem on a 65 year old machine....

There are many smart folks here. I'm quite confident someone will come along to help you troubleshoot the problem.

Good luck and best wishes!

 

[North Idaho Wolfman]

Can you take a picture of the speed control plate, some models of engines have a temp control built into the linkage, I don't think this is the case here but I want to rule it out.

This is the first I've ever heard of this happening to one of these engines.

Usually when you talk speed regulation issues it's a failure of the governor.

But looking at the speed control plate, they changed the design and I'm wondering if the spring inside the cover is damaged or the linkage is sticking at all.

 

[Kubix]

Thanks guys! I knew this was the go to-place for Kubota questions

Can you take a picture of the speed control plate, some models of engines have a temp control built into the linkage, I don't think this is the case here but I want to rule it out.

Will do, as soon as i get to it!

I´ve been working on the engine quite extensively a while ago, in order to rectify the problem, and am pretty sure that theres no such thing as a temp control integrated into the linkage. It´s just a hard cable, running from the throttle lever to the control plate.

When i had the control plate off, i checked the governor springs, which appeared correctly installed and mechanically sound. Maybe they´ve become weak over time? But to my understanding of the system, this would cause just lower revs, right?

Also, while in there, i checked the rack of the injection pump. It seemed to move freely. But when i did this, the engine was cold. Is it possible, that the rack starts binding when the engine warms up and thus cause the issue?

Usually when you talk speed regulation issues it's a failure of the governor.

I thought so too, as only possible solution left i could think of. But speed governing works as designed, as soon as a bit of load is applied

This one really leaves me dumbfounded.

 

[thepumpguysc]

There must be some "slop"{movement} in the linkage somewhere.??
If it were mine.. I would remove the cables, remove the linkage plate & while holding the inside shaft.. try to move the outside levers.. there should be no movement.
If nothing was found, I would start it without the linkage cover on & hold the pump rack & see if it does it..
IF its running up to 3000rpms, you have to SEE something moving..

 

[North Idaho Wolfman]

speed governing works as designed, as soon as a bit of load is applied

Actually it doesn't sound like the governor is working, because if it was, it wouldn't be varying in RPM's from loaded to unloaded.

Can you make a video of it running and post it to Youtube and give us a link to it.

 

[lugbolt]

Had a tractor in a few years back with similar complaints.

Crankcase was contaminated with diesel, due to a failed lift pump diaphragm.

Also had an L2900 in a while back with similar complaint and the injection pump had a problem. I do not mess with the pumps, sent it off and they called & said it was basically junk. Cost as much to repair as replace but the owner wanted it rebuilt and it's his money, so it was rebuilt-at $900-and reinstalled. Worked fine from then on. Had around 4500 hours on it.

 

[Kubix]

I´m totally amazed by the amount of knowledgeable people willing to chime in on this! Thank you guys very much!

There must be some "slop"{movement} in the linkage somewhere.??

I´m pretty sure the linkage can be ruled out, because the problem (engine speed in relation to temp) is always exactly the same and and 100% reproduceable. Slop in linkages (or in the governor acting on the rack) would make the engine Speed Change or fluctuate from time to time during it´s acting up, wherever the slop allows movement by chance- but it behaves always exactly and constantly the same.

Actually it doesn't sound like the governor is working, because if it was, it wouldn't be varying in RPM's from loaded to unloaded.

Sorry, i didnt describe this clear enough. Whenever a slight load is applied to the (warm) engine, it speeds back down to where the throttle lever is set at.
Even turning on the 120 Watts of headlights, is enough of a load for the engine not to rise over the speed set at the throttle lever. Now when additional load is beeing put on the engine (working the hydraulics), the speed stays (virtually) the same. Even under full load, when deadheading all three hydraulic circuits at once, the engine is clearly labouring, but the speed doesnt drop significantly (as long as sufficient throttle, lets say above 1800 rpm, had been previosly applied, of course)
That tells me that the governor is doing its job


Heres another thought of mine: Diesel engines speed is regulated only by the amount of fuel injected into the cylinders. This is, on the Kubota engine accomplished by a governor which acts on the rack of the injection pump, which in turn regulates the amount of fuel injected. The governor is counteracted by the spring which connects to the throttle lever linkage.
When there is no load on the engine, it takes only very little additional fuel for the engine to overspeed.

What if the governor on my machine, for unknown reasons, can control the rack in general but cant move it the tiniest last bit in closed position needed fow an idle on a hot engine?

The fact that eveything is fine on a cold engine and the speed starts rising in parallel with the engine temp after initial warmup, could be explained with reduced friction of the engine, warm engine oil is thinner, internal engine friction is reduced and the engine thus runs faster on the same amount of fuel.

Had a tractor in a few years back with similar complaints.

Crankcase was contaminated with diesel, due to a failed lift pump diaphragm.

Also had an L2900 in a while back with similar complaint and the injection pump had a problem. I do not mess with the pumps, sent it off and they called & said it was basically junk. Cost as much to repair as replace but the owner wanted it rebuilt and it's his money, so it was rebuilt-at $900-and reinstalled. Worked fine from then on. Had around 4500 hours on it.

Interesting! I too am getting a bit of fuel contamination of the engine oil, most likely due to hardened o-rings in the pumps plunger housings. Dont think it causes the issue though, because the CCV on this engine vents to atmosphere and not in the intake manifold; thus the diesel/oil vapors out of the crankcase cant be used by the engine as additional, unmetered fuel.
Also, replacing the engine oil with fresh, uncontamiated stuff has no effect on the speed issue.
Of course it´s possible that the pump has somewhat failed internally and now gives out too much fuel. Guess ill have to look into that and maybe get my hands on a good used one***8230;

But maybe, before i take it all apart, someone has different ideas or can chime in on my abovemetioned "governor-not-beeing-able-to-move-the-rack-the-last-tiny-bit"-theory?

Thank you guys again!

 

[Kubix]

Thank you for all the input. With that, i should be able to find the problem.

Wont be getting to work on the machine at the moment, though (Christmas).
As a matter of fact, working on the injection pump side of the engine is a bit of a pain, because it is located right next to the firewall, deep down in the crammed engine compartment. Access is limited to a small service opening from within the cab. To open it, the heavy seat has to come out (which barely fits through the cabin door). And then theres still the welded fuel tank right in front of it and no space in the cab to fit in there in a working position. No fun.

Because of this, i try to narrow down the problem as much as possible, to avoid taking things apart that dont need to be taken apart.

So, please allow me one more question: Could a (partially) blocked fuel return line from the injectors to the tank cause the symptoms?
Due to pressure in the injectors rising too high and them squirting too much fuel at idle? Or am i on the wrong track with that?

Thanks in advance!

 

[North Idaho Wolfman]

So, please allow me one more question: Could a (partially) blocked fuel return line from the injectors to the tank cause the symptoms?
Due to pressure in the injectors rising too high and them squirting too much fuel at idle? Or am i on the wrong track with that?

Thanks in advance!

Yes a blocked return can cause some weird issues, try disconnecting it at the injectors, add a new line, and sending that to a bottle, and see how it reacts.

And on that same line of thinking, A non venting fuel tank can cause issues too, so try running it with the fuel cap loose.

 

[baaron68]

Kubix- Did you find the problem? I'm having the same issues on a F3680.

 

[Kubix]

No, not yet, sorry... Tons of other projects are piling up.
When ill get to look into it and have some results, ill post my findings!

 

[Kubix]

Finally… the solution

Since the machine is only beeing used very rarely, for some digging jobs around the house and in the garden, the pressure to solve the problem wasnt very high- since it ran and did everything it was supposed to.
But, having a little playtime on hand and beeing inspired by this thread: https://www.orangetractortalks.com/forums/showthread.php?t=32463 i decided to dig into it.

First of all: an oil+filter change (was due anyway). To rule out possible oil dillution by diesel fuel: No effect; engine speed still kept climbing out of control as it warmed up.

Next up: pump and governor. Since the engine sits with the pump/governor side directly next to the firewall, the engine had to come out in order to be able to work on it properly. This in itself was quite some undertaking, but allowed me to also change some much needed gaskets like on the timing cover while underway.

First, i overhauled the injection pump, to make sure it worked correctly and because it had deveolped a leak from the delivery valves. So i bought a kit including all o-rings, gaskets and springs and reassembled it with the new parts. I found that the barrel o-rings had already been replaced, because they were in really good condition. This will become important later...

Then, i removed all governor parts. Didn´t find anything broken, out of place or worn- everything seemed just fine. Except the start spring, which was kind of buggered up.
But since the only thing it does, is pulling the rack to full throttle position when the engine is at a standstill, to aid starting, and is weak and can be easily overcome by the governor, i didnt think it would be the problem.
I replaced it anyway, together with the governor spring and idle and full throttle set screw with original parts. Just to be on the safe side and get a guaranteed factory setting.
Silicon sealant on some flanges gave me the clue though that someone had been in there before me!

After doing all this, i put it all back together, did a coolant flush, and started it up. Started fine, ran fine, but the revs kept climbing again as it warmed up... back to the drawing board


What now. I had nothing to loose, so:

While beeing inside the injection pump, i had gained quite an understanding on how it works. The amount of fuel pumped is set by the rotating angle (rack position) of the machined metering piston, relative to orifices in it´s barrel. Since the barrel can be rotated, too (after loosening the tamper-proof torx screws on top of the pump) to some degree in it´s elongated holes, it is possible to set the amount of fuel metered at this given rack position, individually for each cylinder.
So, in order to reduce fuel, i turned each pump barrel clockwise a little bit.


And now, drumroll please: THE HOT ENGINE IDLED wohhoooo And no matter hot or cold, load or no load, IT JUST HELD THE RPM´s IT WAS SET AT
Finally, i figured it out!


I then played around a bit with these pump settings, to make sure each cylinder got the same amount of fuel by cracking lines and measuring. Wow, this thing has never run that sweet!

Obviously, someone before me had messed up the pump settings when changing the o-rings, and not put the barrels back in EXACTLY in the position they came out. Close-to doesn´t seem to be enough.



I hope, this writeup helps someone with the same (seemingly rather rare) problem!

Thanks all you guys for your input, and see ya (on a kubota)

 

[JustNutsandBolts]

Finally… the solution

Since the machine is only beeing used very rarely, for some digging jobs around the house and in the garden, the pressure to solve the problem wasnt very high- since it ran and did everything it was supposed to.
But, having a little playtime on hand and beeing inspired by this thread: https://www.orangetractortalks.com/forums/showthread.php?t=32463 i decided to dig into it.

First of all: an oil+filter change (was due anyway). To rule out possible oil dillution by diesel fuel: No effect; engine speed still kept climbing out of control as it warmed up.

Next up: pump and governor. Since the engine sits with the pump/governor side directly next to the firewall, the engine had to come out in order to be able to work on it properly. This in itself was quite some undertaking, but allowed me to also change some much needed gaskets like on the timing cover while underway.

First, i overhauled the injection pump, to make sure it worked correctly and because it had deveolped a leak from the delivery valves. So i bought a kit including all o-rings, gaskets and springs and reassembled it with the new parts. I found that the barrel o-rings had already been replaced, because they were in really good condition. This will become important later...

Then, i removed all governor parts. Didn´t find anything broken, out of place or worn- everything seemed just fine. Except the start spring, which was kind of buggered up.
But since the only thing it does, is pulling the rack to full throttle position when the engine is at a standstill, to aid starting, and is weak and can be easily overcome by the governor, i didnt think it would be the problem.
I replaced it anyway, together with the governor spring and idle and full throttle set screw with original parts. Just to be on the safe side and get a guaranteed factory setting.
Silicon sealant on some flanges gave me the clue though that someone had been in there before me!

After doing all this, i put it all back together, did a coolant flush, and started it up. Started fine, ran fine, but the revs kept climbing again as it warmed up... back to the drawing board


What now. I had nothing to loose, so:

While beeing inside the injection pump, i had gained quite an understanding on how it works. The amount of fuel pumped is set by the rotating angle (rack position) of the machined metering piston, relative to orifices in it´s barrel. Since the barrel can be rotated, too (after loosening the tamper-proof torx screws on top of the pump) to some degree in it´s elongated holes, it is possible to set the amount of fuel metered at this given rack position, individually for each cylinder.
So, in order to reduce fuel, i turned each pump barrel clockwise a little bit.


And now, drumroll please: THE HOT ENGINE IDLED wohhoooo And no matter hot or cold, load or no load, IT JUST HELD THE RPM´s IT WAS SET AT
Finally, i figured it out!


I then played around a bit with these pump settings, to make sure each cylinder got the same amount of fuel by cracking lines and measuring. Wow, this thing has never run that sweet!

Obviously, someone before me had messed up the pump settings when changing the o-rings, and not put the barrels back in EXACTLY in the position they came out. Close-to doesn´t seem to be enough.



I hope, this writeup helps someone with the same (seemingly rather rare) problem!

Thanks all you guys for your input, and see ya (on a kubota)

Hi,
I'm putting this here as a placeholder.
I am having the same issue on a B21 with D1005 engine.

If this fixes it, I am going to send you a present.

 

[lugbolt]

either someone had it apart (like you said) OR another possibility...someone "bled" the lines at the pump, and sometimes people don't really know what they're doing there and will rotate the delivery valve in the housing. I've seen this countless times over the years.

glad you got it going!

 

[JustNutsandBolts]

So this repair addressed my issue too. It hangs around 2800 max now and does not go above that. I had it running for over 30 min with no issues.

Mine did not look like it was tampered with.

But now i have fuel seaping between the block and the injection pump, coming from the "shims".

I looked in the service / shop manual and it says the RTV is not necessary. Is that correct? If i do use RTV, should i apply it on bottom and the top of each shim?

 

[whitetiger]

So this repair addressed my issue too. It hangs around 2800 max now and does not go above that. I had it running for over 30 min with no issues.

Mine did not look like it was tampered with.

But now i have fuel seaping between the block and the injection pump, coming from the "shims".

I looked in the service / shop manual and it says the RTV is not necessary. Is that correct? If i do use RTV, should i apply it on bottom and the top of each shim?

There should not be any fuel at the joint between the pump and block, only engine oil. If you do have fuel there either the injection pump or lift pump is leaking fuel into the crankcase.
Check your engine oil level, clean around the injection pump with brake cleaner, blow it off to dry it, and watch closely as to where it is coming from. The fuel may be running down the pump and you are just seeing it at the joint.

 

[JustNutsandBolts]

There should not be any fuel at the joint between the pump and block, only engine oil. If you do have fuel there either the injection pump or lift pump is leaking fuel into the crankcase.
Check your engine oil level, clean around the injection pump with brake cleaner, blow it off to dry it, and watch closely as to where it is coming from. The fuel may be running down the pump and you are just seeing it at the joint.

It might be leaking from the top, I remember seeing some bubbling.
Should I replace the o-rings before I put it back on. It's a pain to RTV everything and disassemble again.

See this video I found for the O-rings:

 

[JustNutsandBolts]

Its leaking from where i drew the red lines.

I put similar size o-rings in there. I guess they were not right size. This sucks.

EDIT: I apologize, let me make a correction.
I just ran into the diagrams in this post :

Quick question - the dreaded delivery valve holder leak - Bosch K-type injector pump

No. 4 holder is weeping (has been for months if not years - previous owner mentioned it), and I suspect no. 3 is just starting to as well - see photo. From the numerous threads on the subject I've decided to fix it myself (it's been wonderful reading the contributions of people on this forum...

www.orangetractortalks.com

I did not replace the O-ring on the delivery valve holder ( the part where I put the arrows on). I replaced the 2 on the delivery valve itself. I may be able to fix this if I tighten down on these delivery valve holder but I cannot find a wrench to fit in that middle one.

Check this picture for more detail found in (I did not replace this o-ring) this post:

https://www.tractorbynet.com/forums/files/parts-repairs/606457d1558957256-re-sealing-your-leaking-line-cbd6b2aa-1b75-4af3-abb1-1cae29ca50d7

 

[Jim Leap]

Its leaking from where i drew the red lines.

I put similar size o-rings in there. I guess they were not right size. This sucks.

EDIT: I apologize, let me make a correction.
I just ran into the diagrams in this post :

Quick question - the dreaded delivery valve holder leak - Bosch K-type injector pump

No. 4 holder is weeping (has been for months if not years - previous owner mentioned it), and I suspect no. 3 is just starting to as well - see photo. From the numerous threads on the subject I've decided to fix it myself (it's been wonderful reading the contributions of people on this forum...

www.orangetractortalks.com

I did not replace the O-ring on the delivery valve holder ( the part where I put the arrows on). I replaced the 2 on the delivery valve itself. I may be able to fix this if I tighten down on these delivery valve holder but I cannot find a wrench to fit in that middle one.
View attachment 52835


Check this picture for more detail found in (I did not replace this o-ring) this post:

https://www.tractorbynet.com/forums/files/parts-repairs/606457d1558957256-re-sealing-your-leaking-line-cbd6b2aa-1b75-4af3-abb1-1cae29ca50d7