M59 and EGR Valve

[rScotty]

I'm hoping you do remove the EGR so the rest of us can see what happens, but wouldn't an easier/safer experiment be to advance the injection timing? It is widely believed to be the big issue with Interim Tier 4 at high elevation but I don't know of a single person who has solved the cold stumble/smoke problem at 7000 ft or above. My L5740 has it worse than the MX5100 did, yet they are similar engines.

I'm kinda surprised to hear so much about advancing the injection timing. It's something that is easy to do on gas engines, but harder on diesels. Interesting idea. though; do you know where did it came from originally...anybody know that? Anyway, how is advancing the burn one on our mechanically-injected motors? Is it done by modifying the injectors or at the pump cam? I don't believe that the interim tier IV has any type of computer comtrolled injection timing - although I could be wrong there. Mechanically, I can see several ways to do it... but all of them involve kinda advanced mechanical work.

But to answer your question, here is what I wrote in message #10:

"But not so sure I agree that advancing timing is what I want to do. On any type engine, advancing the timing increases burn time and therefore the effective compression ratio...so it gives more HP......but it then defeats some of the HP gain because the burn begins at such an unfavorable crank-torque angle. And it is tricky to get advancing things right; timing that is just a little too far advanced can really hammer on the bottom end wear. All in all, I'd rather come up with a solution where I give up some HP in exchange for a better burn ratio. So far that seems to either be via modified injectors or EGR. Keeping in mind that I'm in this for a nicer, more economical run - and for longevity; the tractor has HP to spare."

That's what I think....well, it's what I think so far....opinions are always malleable. Sure would like to get all of our tractors working better at high altitude even if it does cost some HP.
rScotty

 

[caballero59]

On the 5W-40, are you talking about CK-4? There are some 5-w40 still available at CJ4.

I'm sure there is oil available but I like Rotell T6 and I heard this is not spec'ed for the M59 which disappointed me. I don't like for things to become so ultra specific and complicated.

 

[caballero59]

... It is widely believed to be the big issue with Interim Tier 4 at high elevation but I don't know of a single person who has solved the cold stumble/smoke problem at 7000 ft or above. My L5740 has it worse than the MX5100 did, yet they are similar engines.

This is interesting and parallels my own experience. My L39 and ZD326 (neither with EGR) start up at 8000' with a puff of black smoke and run smooth as glass. The M59 stumbles for a few seconds. I talked to two dealers and received the usual comments of fuel filters, etc, and one suggested maybe the injectors had been damaged. I didn't know this startup problem was the talk of the town (so to speak) but it does comfort me to know it isn't just mine. When I hauled my M59 from Colorado to KS last week, I stopped at a dealer at an elevation of 5000' and requested that the mechanic observe the starting cycle. Cranked right up and ran perfect with no stumble or stutter and that is is first time a mechanic at a dealer mentioned elevation as a possible culprit for when my tractor was giving these symptoms. Evidently, there is a wide range of opinions, skills, and a lack of consensus with dealer mechanics! It also starts and runs perfect in KS. So I do believe the altitude was the culprit.

 

[caballero59]

To advance the timing on a 12v Cummins with mechanical pump, you break the pump gear loose on a tapered shaft that sits behind the timing cover and rotate it sightly and then retighten. I've heard the Kubota uses shims. If it was as easy as 1 shim /x.x degrees, then I would do it because it would be a deterministic process. If the process is similar to the Cummins, I won't touch it. Its easy to change the timing on the Cummins but its tricky to set it to a precise degree of advance and if there is the slightest bit of oil on the pump gear shaft, it can suddenly slip and your truck won't run. I only mention these things to explain why I would be slow to monkey around with the Kubota pump.

 

[TMGT]

That engine uses shims under the injector pump assembly to adjust timing.

I'm curious to what the M59 oil spec is that T6 Rotella doesn't meet it.
I use T6 in my 6.7 cummins with egr and it meets the specs for every diesel I know of with egr and dpf.

 

[rScotty]

To advance the timing on a 12v Cummins with mechanical pump, you break the pump gear loose on a tapered shaft that sits behind the timing cover and rotate it sightly and then retighten. I've heard the Kubota uses shims. If it was as easy as 1 shim /x.x degrees, then I would do it because it would be a deterministic process. If the process is similar to the Cummins, I won't touch it. Its easy to change the timing on the Cummins but its tricky to set it to a precise degree of advance and if there is the slightest bit of oil on the pump gear shaft, it can suddenly slip and your truck won't run. I only mention these things to explain why I would be slow to monkey around with the Kubota pump.

Moving the gear (or shimming the pump cam follower) could advance the timing so that the burn would start sooner, but I don't quite see how it would change the duration of the burn....duration being the other half the changes we want to make in the combustion timing or else all we've done is move the same burn to a less favorable crank angle. Hmmm.....maybe the decreased oxygen slows the burn & that provides the duration? Could be, but would require a slightly higher cetane fuel because it has to happen at lower compression....but oops.....higher cetane shortens burn again. Not easy.

But so far I can't see the EGR helping things in any way at high altitude.
rScotty

 

[FatTire]

Where did the timing idea originate for Interim Tier 4? I honestly can't remember, so I did a google search for threads like "Kubota injection timing shim" and "Kubota Tier 4 injection timing". There are quite a few threads on TBN and elsewhere, but there is a lot of misinformation in many of these. And not a lot of people who actually did anything, most of it is actually goes back to "my dealer said". Here is a typical thread, FWIW. http://www.tractorbynet.com/forums/kubota-owning-operating/193924-l5740-cold-start.html That thread has a post #10 where someone says they did the fix, but really no details. Again this is typical, I did not see any threads where someone detailed what they did and their results.

Two things that show up a lot in these threads is that someone will ask if you use your glowplugs, or state that smoke is normal when starting a diesel, etc. etc. So that's not what rScotty is talking about here.

 

[kuboman]

I removed the egr on my 5740 mostly just to clean it up. By removing the egr valve and the cooler it gets rid of a lot of useless clutter. I did use the 2 coolant ports to plumb in a circulating block heater. I did not notice any difference in starting. It still smokes at startup which is quite annoying and maybe someday I will try the timing advance. But I have to say the engine is timed to 19* btdc which is a standard advance for a lot of diesels.I live at 4000 asl so maybe that has something to do with it.

 

[caballero59]

One wonders why there is not more consistency and predictability? The M59 started completely normally at 5000' (the one time I tried it) and every time at 2000'. It would be nice to have a confident answer of how many shims to add/remove if the EGR system is removed and also if anything else needs to be changed to make the motor "normal".

 

[rScotty]

I removed the egr on my 5740 mostly just to clean it up. By removing the egr valve and the cooler it gets rid of a lot of useless clutter. I did use the 2 coolant ports to plumb in a circulating block heater. I did not notice any difference in starting. It still smokes at startup which is quite annoying and maybe someday I will try the timing advance. But I have to say the engine is timed to 19* btdc which is a standard advance for a lot of diesels.I live at 4000 asl so maybe that has something to do with it.

Thanks for that info. In my own research I am beginning to understand more about how timing the onset of the burn changes soot, N0x, fuel consumption, and power. But I'm not convinced that any of these make a difference in starting. BTW, how did you end up at 19 degrees BTDC??

For anyone following along, both the M59 and Kuboman's L5740 use the same V2403 series 2.4 liter engine. In fact a lot of Kubota's L or M 40, 50 and some 60 series tractors also use that same engine.
I'm finding out that our 2.4 liter is a surprisingly old and simple style diesel motor with old style mechanical injection. The basic design is old and proven; the feeling I get as I look at it is that I'm looking at an engine design from 50 years ago. It sports a fairly low pressure injection pump with injection timing set by shims and injector springs rather than by a computer. It makes surprisingly good power and is an extremely durable engine - but like most of the older design diesels it is a low RPM type and really prefers constant speed operation. It is inherently a dirty engine when changing RPM. There isn't much way around that. and little that can be done internally to make less particles and N0x. Constant speed is preferred because unlike modern computer-controlled diesels, this old design just doesn't have any easy way to change a lot of the operating parameters - like timing of injection, injector duration, and valve timing. This old guy is all mechanical. That's what makes it simple in design, but not very efficient. The EGR mod itself that we saw added in 2007 and that I am thinking of defeating seems to be specific for N0x reduction at the expense of making more soot. Soot reduction came later (2016 or so) with even more add on systems bolted onto the same basic engine recently to control soot for full Tier IV compliance.

To give you an idea of the operating paramaters, for the version of the 2.4 liter with EGR, injection timing is set by the factory for 8.5 to 10 degrees BTDC. That's using Kubota's setting method which is a really old method that I recognize as an attempt to compensate for the inherent lag between when an injection cycle starts and when fuel is actually injected. That lag itself can be ten degrees or even more in an older engine. So there's a bunch of fudge factors here. If we were setting the injection timing with a gauge and a degree wheel it would probably be set to be more degrees BTDC (because of the lag). I personally wouldn't modify the injection timing without first doing a complete test of the injectors themselves and attempting to get some idea of the wear on the injection cam. All this is covered in detail in the OEM workshop manual.

I think I will eventually remove the EGR from mine....or defeat it somehow in order to make it pollute less at high altitude. But I doubt that there is any complete fix for the smoke when changing RPM.
rScotty