L5740 Cold Start

[MyJoBota]

As the original poster I would like to thank all that have shared to this thread. The video has been removed.

 

[Johnbro]

Interesting thread... I can honestly say I've never , ever, in over 25 years of diesel repair and fuel injection work seen a diesel set at 0 degrees BTDC for start of fuel delivery. Most are between 15 and 35 degrees BTDC depending on the combustion chamber design and compression ratio.

I have attached a picture of the engine label on my 3400, which works perfectly normal in cold weather in my opinion. Notice the injection timing is 17.25 degrees BTDC.


We've recently done some diesel engine testing through work involving attaching a pressure sensor to the fuel injection line and another one attached to the cylinder head to measure the pressure rise in both areas vs. degrees of crank rotation on a running, loaded engine. There is also a sensor in the injector tip to measure when the needle lifts and injection actually begins. With timing set at 32 degrees BTDC, the actual ignition point is approximately 6 to 9 degrees after TDC on the power stroke. Diesels have a phenomonon called ignition lag, measured in degrees of crank rotation from the time fuel is injected into the combustion chamber until it begins to burn. This is a normal facet of diesel operation, and is why fuel must be injected well before TDC.

That's a V16 turbo intercooled engine turning at 1800 rpm and making well in excess of 1000 HP at full power. We had reliability issues that led to a study of what was happening with combustion pressures and fuel timing.

After experimenting with different injection timing, it was discovered that retarding the timing even 5 degrees resulted in excessively high exhaust gas temperatures, poor combustion, and reduced power for an equivalent amount of fuel consumed. Advancing the timing beyond the original design resulted in extremely high cylinder pressures, cracked and broken connecting rods, etc.

That's 5 degrees or less of change, and here we're discussing retarding it over 15 degrees?? Come on people, have some faith in Kubota and the other manufacturers. They DO know what they're doing, it's one of the reasons they're one of the leaders in small diesels worldwide.

Changing timing affects primarily cylinder pressures, but does have a secondary effect on exhaust gas temperature. Changing the amount of fuel delivered affects primarily the exhaust temperature, with a slight change in cylinder pressure. The two variables are quite different and both are independently adjustable on all diesels I'm aware of.

There's a lot more to adjusting fuel timing than most folks realize. You're changing a design parameter that's been carefully set to provide a balance of the best performance and engine life, while still meeting emission standards.

As some have tried to point out, diesels don't work particularly well when they first start in frigid conditions. Cylinder temps barely support combustion, so yes they will run rough and exhibit grey-white smoke until the cylinders warm up. There's normally a puff of heavy black or grey smoke on start-up, then it will reduce to a lesser level and eventually go away entirely as the engine warms up. The governor will keep adding fuel to maintain idle.

Suggesting that the timing should be set to 0 degrees BTDC regardless of what Kubota has designed it to be, makes absolutely no sense to me. I seriously doubt any dealer will warranty an engine that has had that done, I certainly wouldn't.

And that, my friends, is my opinion.

Sean

Nice! Thanks for the input and it's good to see some actual data. Very helpful post.

 

[leonz]

Since Kubota in its ultimate wisdom has been advancing the timing to 8 degrees at T.D.C., to reduce the NOX, CO2, and Diesel Exhaust Particulate Concentrations at the exhaust pipe in emmisions tests to comply with the new EPA guidelines for Lawn Mowers With Diesel engines rather than simply leaving them Set and BALANCED as delivered from Kubota-Japan and installing a very small diesel exhaust gas scrubber before the so called muffler what do you suggest the new owners oif S.C.U.T., and C.U.T.S.'s do?, due to the vibration whch can cause potential nerve damage from wood cutters disease because of the massive power delivered and absorbed by the tractors frame and chassis?


You have to understand that the engines are not completely isolated and the throw wieght created by the act of unbalanced loading internal combustion creates huge centrifugal forces where the mass of the tractor is absorbing these forces.

These engines are used in other applications with zero issues OR VIBRATION
so>>>>>>>>>..........................................................:thumbsup:



If you want to really understand vibration you should investigate wood cutters disease.

AND if A "major" Kubota Engine reseller and rebuilder says" THERE SHOULD BE NO VIBRATION at idle; what does that say about what these engines are found to be set at
and when they are reset to zero T.D.C.????????????????

 

[bitseeker]

Since Kubota in its ultimate wisdom has been advancing the timing to 8 degrees at T.D.C., to reduce the NOX, CO2, and Diesel Exhaust Particulate Concentrations at the exhaust pipe in emmisions tests to comply with the new EPA guidelines for Lawn Mowers With Diesel engines rather than simply leaving them Set and BALANCED as delivered from Kubota-Japan and installing a very small diesel exhaust gas scrubber before the so called muffler what do you suggest the new owners oif S.C.U.T., and C.U.T.S.'s do?, due to the vibration whch can cause potential nerve damage from wood cutters disease because of the massive power delivered and absorbed by the tractors frame and chassis?


You have to understand that the engines are not completely isolated and the throw wieght created by the act of unbalanced loading internal combustion creates huge centrifugal forces where the mass of the tractor is absorbing these forces.

These engines are used in other applications with zero issues OR VIBRATION
so>>>>>>>>>..........................................................:thumbsup:



If you want to really understand vibration you should investigate wood cutters disease.

AND if A "major" Kubota Engine reseller and rebuilder says" THERE SHOULD BE NO VIBRATION at idle; what does that say about what these engines are found to be set at
and when they are reset to zero T.D.C.????????????????

So Leonz, you suggest that injection timing at zero T.D.C = zero issues OR VIBRATION?

BTW, Wood-cutter's disease is most commonly attributed to lichen contact sensitivity.

 

[leonz]

Zero issues and zero vibration as it is balanced.

 

[Jerry/MT]

Interesting thread... I can honestly say I've never , ever, in over 25 years of diesel repair and fuel injection work seen a diesel set at 0 degrees BTDC for start of fuel delivery. Most are between 15 and 35 degrees BTDC depending on the combustion chamber design and compression ratio.

I have attached a picture of the engine label on my 3400, which works perfectly normal in cold weather in my opinion. Notice the injection timing is 17.25 degrees BTDC.


We've recently done some diesel engine testing through work involving attaching a pressure sensor to the fuel injection line and another one attached to the cylinder head to measure the pressure rise in both areas vs. degrees of crank rotation on a running, loaded engine. There is also a sensor in the injector tip to measure when the needle lifts and injection actually begins. With timing set at 32 degrees BTDC, the actual ignition point is approximately 6 to 9 degrees after TDC on the power stroke. Diesels have a phenomonon called ignition lag, measured in degrees of crank rotation from the time fuel is injected into the combustion chamber until it begins to burn. This is a normal facet of diesel operation, and is why fuel must be injected well before TDC.

That's a V16 turbo intercooled engine turning at 1800 rpm and making well in excess of 1000 HP at full power. We had reliability issues that led to a study of what was happening with combustion pressures and fuel timing.

After experimenting with different injection timing, it was discovered that retarding the timing even 5 degrees resulted in excessively high exhaust gas temperatures, poor combustion, and reduced power for an equivalent amount of fuel consumed. Advancing the timing beyond the original design resulted in extremely high cylinder pressures, cracked and broken connecting rods, etc.

That's 5 degrees or less of change, and here we're discussing retarding it over 15 degrees?? Come on people, have some faith in Kubota and the other manufacturers. They DO know what they're doing, it's one of the reasons they're one of the leaders in small diesels worldwide.

Changing timing affects primarily cylinder pressures, but does have a secondary effect on exhaust gas temperature. Changing the amount of fuel delivered affects primarily the exhaust temperature, with a slight change in cylinder pressure. The two variables are quite different and both are independently adjustable on all diesels I'm aware of.

There's a lot more to adjusting fuel timing than most folks realize. You're changing a design parameter that's been carefully set to provide a balance of the best performance and engine life, while still meeting emission standards.

As some have tried to point out, diesels don't work particularly well when they first start in frigid conditions. Cylinder temps barely support combustion, so yes they will run rough and exhibit grey-white smoke until the cylinders warm up. There's normally a puff of heavy black or grey smoke on start-up, then it will reduce to a lesser level and eventually go away entirely as the engine warms up. The governor will keep adding fuel to maintain idle.

Suggesting that the timing should be set to 0 degrees BTDC regardless of what Kubota has designed it to be, makes absolutely no sense to me. I seriously doubt any dealer will warranty an engine that has had that done, I certainly wouldn't.

And that, my friends, is my opinion.

Sean

I agree with your well thought out response and conclusions, for whatever that's worth. Retarding the injecton timing by 17.5ï° from the spec is excessive and makes no sense relative to the OP's stated concern. Once you disregard the spec timing, you're on your own regarding engine operation, performance, and engine life. Without the ability to monitor EGT, you can easily damage your engine. I would recommend the OP have his timing checked to make sure is is per spec.

I have NH TD95D with an Iveco Tier II engine. It has a ****** device on pump that's controlled by water temperature. The engine starts with slightly retarded injection timing and then when a certain water temperature is reached (I'm not sure of the exact number but I recall it's like 90-100ï°F) the timing is advanced to the normal advance schedule. It starts an idles well in all temperatures without any roughness except when it first fires in very cold conditions(-10F), just like any otherd diesel I have.

Asking a dealer to change the timing is liable to get a negative response. These engine settings are certified by the EPA( whether we like it or not) and can't legally be altered if they are for emmission controls. Just like our cars. I didn't witness the OP's start up on YouTube. If he has a lot more than the ordinary cold start roughness then maybe he's a got a bad injector or some other mechanical problem. I don't see how retarding the timing will fix it.

As far as the original post, does this machine have a block heater on it? If so, was it used? I have block heaters on( or will have as I haven't installed the NH one yet) and I get "soft" easy starts on my other diesel tractor in the coldest of conditions that we experience in Western Montana (-20F). In really cold conditions use whatever starting aids you have on the tractor to make starting as easy as possible. And get that timing checked.

 

[Chilly807]

Wood cutter's disease, hmm? I'd not heard of it until today, but after doing a bit of research it does seem to be caused by lichen contact. No more cutting wood in me underwear from now on.

A timing check is a good idea, getting a dealer to do it without charging an arm and a leg is going to be the trick.

I had a chuckle when I looked at the engine label on my 3400. Not 17 degrees, not 18 degrees, but 17.25... Not sure how they set for that quarter of a degree, but I'd like to watch the procedure.

Sean

 

[Jerry/MT]

Wood cutter's disease, hmm? I'd not heard of it until today, but after doing a bit of research it does seem to be caused by lichen contact. No more cutting wood in me underwear from now on.

A timing check is a good idea, getting a dealer to do it without charging an arm and a leg is going to be the trick.

I had a chuckle when I looked at the engine label on my 3400. Not 17 degrees, not 18 degrees, but 17.25... Not sure how they set for that quarter of a degree, but I'd like to watch the procedure.

Sean

I have a feeling they set it statically with some sort of special tool. That's how the timing on my TD95D is set. I haven't read the details but there is a special tool involved.

 

[beppington]

I had a chuckle when I looked at the engine label on my 3400. Not 17 degrees, not 18 degrees, but 17.25... Not sure how they set for that quarter of a degree, but I'd like to watch the procedure.

No big deal: Just set it half-way between 17.2 degrees & 17.3 degrees :laughing:

That should be close enough anway :confused2:

 

[leonz]

I only know of wood cutters disease and the nerve damage because of the first diagnosis of Japanese wood cutters who started using motorised chain saws after the second world war which did not have the vibration isolated chainsaw engines which is what I am familiar with and which I am referring to in detail.