Correct engine idle speed during warm up??

[jodebg]

Recently purchased a Kubota B7800.

What is the correct idle speed setting for winter warm up?

The manual says to set the throttle lever to the half way position
to start the tractor, but does not offer an idle speed during the warm up
phase.

 

[kco]

Some, including me feel starting at half throttle is not a good idea. I'm not that experienced but don't like the feel and sound of starting at 1/2 throttle.

My Kioti DK35 says to set the throttle lever to the "neutral" position. I THINK that means idle. Mine always starts fine at idle and I always let it run several seconds or more depending on the ambient temperature and sound. There is a definite difference in sound from first start to several seconds later. Once it is running smoothly I increase it to about 1200 RPM and let it idle there for the warm up period (again depending on the temperature).

In the snow season I start the tractor and do hand clearing of sidewalks while the tractor warms up(approx. 20 minutes).

 

[Wolfy]

I start my Ford tractors at full throttle, then VERY QUICKLY slow them to 1,000 rpms. My Kubota likes to start more near idle, then I leave it at idle, but it is only 10 years old.

 

[bigbull338]

i idle my tractor at 900rpms.thats the throttle pulled down as low as itll go.

 

[JerryK]

A lot of diesels will not make heat unless they are turning 1300 or so RPM. A gas motor will warm up at idle, but a diesel... with all that cast iron.. usually big radiator.. won't make enough heat at idle to burn the fuel efficiently. Not saying race the cold motor, but get some RPM into it after you think the oil is circulating good... I let mine warm up around 1400 plus or minus... I also try to get the tractor moving after about ten minutes, to start warming up the rest.

 

[LJH]

Tach doesn't work on mine so after she fires up I just set the throttle at what sounds right - I'm guessing somewhere in the 1000 rpm range. Could be doing it completely wrong, but so far so good.

 

[TripleR]

This comes up on a pretty regular basis and never has there been nor ever will there be a consensus. Over the years, I have tried several on different tractors, some now over forty years old. I now warm mine up at about 1200-1500RPM based on my manuals, but I sure don't know which is "best".

 

[cartod]

I warm mine up at full throttle.







:laughing:

 

[YesDeere]

I usually start mine at idle and then raise it to 1200 rpms. Any lower and it won't warm up. Plus idling a cold diesel can allow fuel to get past the rings and dilute the oil. Anyone else ever hear that? I was told that a long time ago and just stuck with it.

 

[wmonroe]

I start mine at about 1000 rpm's (idle is about 800) and once it smooths out and I feel everything is circulated, usually 1 - 2 minutes, I bump it to about 1200-1300 rpm. If it's really cold I'll let it there for about five minutes and then go to about 1600 rpm. This all depends on temperature though and I do it mostly by sound and feel of the machine.

 

[ray66v]

In the winter, you have cold air that is much thicker, (denser), than it is in the summer. This means there is more air going into the engine when it cranks.

When you have more air than fuel, the mixture can get too lean for it to start.

Since there are generally no computers on these engines, you have to adjust the mixture yourself. You do that of course, by opening the throttle some. More fuel enriches the mixture back to the same level it would be in warm weather.

A good way to determine the proper throttle setting for cold weather starting, is to start cranking with the throttle at idle, and while cranking, slowly advance the throttle lever until the engine fires. Note the throttle setting the engine fired at, and you can try that as the starting point next time.

If the engine does not fire after 5-8 second of cranking, always stop, and return to heating the glow plugs again. Cranking until the battery dies only causes additional frustration.

Sometimes, when it's really cold, and depending on the condition of your engine, you may find you need to heat the glow plugs for 30 seconds or more, to get a good start.

To the OP: Diesel engines cool at low idle speed. You need a nice high idle speed to warm one up in cold weather efficiently. Can't tell you what that is, never owned one with a tach. Just open the throttle until it is running smoothly at a nice speed.

 

[FatTire]

The manual for my Kubota says warm up at 1/2 rated RPM, so for my machine that's 1350 RPM.

 

[Gordon Gould]

My Kabota manual says use 1/2 throttle in the winter. I have found this to much for my liking as it starts rough then races. I open the throttle lever slightly then after it starts adjust it to a smooth running 1200 to 1500 rpm. Summer idle is 900 rpm on mine.
Just find a system where it starts easy and smooths out quickly and you will be OK I would think.

 

[Poopdeck Pappy]

I start mine at idle and after about 10 seconds I bump it up to 1200 - 1300 rpm. Then, after a minute or two, bump it to 1500+/- and leave it there for a few minutes. But we don't have the really cold temps a lot of you guys do.

After the tractor warms up for 2 - 3 minutes, I work the hydraulics slowly to circulate the fluid in the cylinders to the rest of the system.

 

[JerryK]

About 10 degrees this morning, probably about 20-30 in my barn where the tractor sleeps. That area is just outside the 16X40 area I heat during the day. Fired up the tractor [ did not use the grid heater ] then brought it up to about 1200. Lifted the blower up so I could take the timbers under it out, then when and opened the barn door..this all took a couple minutes. Backed it out of the barn, dropping the blower once it was outside and pushed the blower/snow across my turn around area. Ramped her up to about 1400... then went and closed the barn, checked the stove, and put on my winter hat/gloves/locked barn.... maybe four minutes. Went back out and fire up the blower to clean out the snow that was packed in it when I first backed up.. then cleaned about four swipes in front of the barn.. Drove about 500 feet out to the mail box, cranked her up to about 2000... and had at it. That's I the baby'n mine gets.....

 

[zd21]

I agree with Gordon Gould's views. The Kubota Corporation is not an authority on each particular starting situation, so its advice must be generic. Examples of possible user differences include ambient temperature, viscosity of oil used, viscosity index, accumulated engine hours, how heavy a load the engine will operate under after warmup, etc. Look at it another way: Kubota engines provide marvelous durability world wide under all the variety of engine users, climates, oil brands, etc. A fair conclusion is that the engine is not sensitive to how it is warmed up.

 

[crazyal]

I shut it off with the engine at about 1400 rpm and leave it there. That's where I start it and adjust it to around 1300 then let it run (with the clutch depressed) for several minutes when really cold. The sooner you can get the oil flowing to all four corners of your engine the better. 1500 or more sounds like it's racing to me and I think the engine oil will reach the pressure limiter so any faster will not do any good.

 

[dixstir]

I have always let my diesels run 1500 or so during warm up summer and winter, when they run slower at idle they contaiment the oil with turns it black a lot sooner after a oil change. I had a 4 cylinder diesel in a 1956 chevy pickup with over 3 hundred thousand and it was still running good when it went to a new owner, still miss it.

 

[Raspy]

In the winter, you have cold air that is much thicker, (denser), than it is in the summer. This means there is more air going into the engine when it cranks.

When you have more air than fuel, the mixture can get too lean for it to start.

Since there are generally no computers on these engines, you have to adjust the mixture yourself. You do that of course, by opening the throttle some. More fuel enriches the mixture back to the same level it would be in warm weather.

A good way to determine the proper throttle setting for cold weather starting, is to start cranking with the throttle at idle, and while cranking, slowly advance the throttle lever until the engine fires. Note the throttle setting the engine fired at, and you can try that as the starting point next time.

If the engine does not fire after 5-8 second of cranking, always stop, and return to heating the glow plugs again. Cranking until the battery dies only causes additional frustration.

Sometimes, when it's really cold, and depending on the condition of your engine, you may find you need to heat the glow plugs for 30 seconds or more, to get a good start.

To the OP: Diesel engines cool at low idle speed. You need a nice high idle speed to warm one up in cold weather efficiently. Can't tell you what that is, never owned one with a tach. Just open the throttle until it is running smoothly at a nice speed.

This is very misleading and inaccurate. Diesels only fire from the heat of compression. If they cannot produce a high enough compression temperature they will not fire wether there is fuel or not. It has nothing to do with being "lean". They do not run "lean" like a gas engine does, they ALWAYS have excess air, but are not "lean" in the sense that it might prevent them from firing or because it is the wrong mixture. There is always an excess of air unless they are running at full throttle. Rich and lean has nothing to do with starting a diesel like it does on a gasser and adjusting the throttle does not change the mixture. As long as they are getting enough fuel to produce the energy to run and they are producing enough heat, they will start. Diesels cannot warn up very well because they are usually quite massive and they always have an excess of air being pumped through them. This extra air has a cooling affect. There is very little extra heat being produced, and what there is is being sent out the exhaust instead of into the cooling system. You don't have to have a diesel fully warmed up to put it to work. A light load after 30 seconds or so will help it warm up and reduce condensation. Running it for long periods cold is more of a problem because it builds up carbon, causes a lot of condensation and wastes fuel. The condensation is water that is not a lubricant. Imagine the rings running up and down the cylinder walls lubricated by water. It's better to get it warmed up soon with a light load and get the oil to it's proper viscosity.

In Alaska, on the pipeline, many diesels were allowed to idle for long periods to warm them up, or keep them warm and ready to use. This caused a lot of engine failures and extreme carbon build up. It's much better to not baby a diesel. Get the oil circulating, which only takes a few seconds, and then start giving it a light load so it can produce some heat, stop condensing and stop producing a lot of cold carbon deposits. Running cold is the problem.

 

[ddb123]

As you can see, there are a lot of different methods out there and pretty much everyone will swear by theirs as few of us have blown up a diesel. My advice is to start it between 1000-1200 rpms (half my rated rpms would be 1300) and let it warm up where it sounds good, usually somewhere between 1300 and 1500. That's what I do, anyway, and I haven't died from it yet.