Oil & Fuel Never idle a diesel??..

[r0GuE]

I'd like to check on the accuracy of a statement made to me by a guy who used to work at a trucking company and seems to know about diesels etc.
He claims that you should never low idle a diesel because the fuel does not atomize properly and therefore condenses on the cylinder walls interfering with proper lubrication.
His recommendation is to start the tractor and immediately move it to 1000 - 1500 RPM (I have a BX so this setting would be an estimate).
I know I've heard of truckers idling their rigs all night, but he said that is because they are afraid they won't be able to restart them and they also need the power for heat etc. Besides, it's usually not their rig and the rig has extra lube equipment etc. But for a small tractor, he recommends no idling.
So what do you all think about this.
Also, Happy Holidays to all!


Rogue

 

[Jeff396]

Wow, that would be news to me. I thought that was one of the plusses for deisels that they were able to idle for long periods of time. My brother in law, who works at the GM proving grounds in the military division in Michigan, used to leave his diesel Suburban idle when the weather was really cold while he was at work. I guess with no plugs available he was afraid he would not be able to start it.

I have a B7500 and I thought it idled kinda high. I believe it sits at about 1100 rpm. Is this too high, does anyone know the spec for this adjustment?



Jeff

 

[cowboydoc]

That post is true and it isn't true. Big rigs don't let them idle all night so they can start them the next day, although yes that can be true on really cold nights. Unless they are stopped for the night they let them idle. Anyway the point is that yes at a constant slow idle speed after about 10 minutes all of the fuel will not burn and it does cause deposits. What big rigs and even my pickup have is what is called an auxillary idle controller that automatically varies the speed of idle so that you don't get the deposits. It's still good practice to idle a diesel if it is going to be less than 10 or 15 minutes. If it's more than 10 minutes just bump up the idle to a higher speed and you won't have to worry about it. That's also why you see alot of guys get on their tractor after it has been idling and rev it up a few times to get the unburned deposits out of it.

 

[upgw]

When she's puffing a little blue on startup at 8500 hours you can wonder if maybe you idled her too much in the last 30 years... /w3tcompact/icons/smile.gif...

Isn't diesel a bit of a lubricant anyway? Diesel's have less top-wear than gas engines, and the only worn out small gas engines I've seen had plugged cooling fins. I wouldn't worry about it.

- Patrick W.

 

[MikePA]

<font color=blue>Isn't diesel a bit of a lubricant anyway?</font color=blue>

Based upon my experience walking on the concrete pad where my local diesel pumps are, I'd say it's a great lubricant! /w3tcompact/icons/shocked.gif

 

[Anonymous Poster]

IF THE TRACTOR IS GOING TO IDLE FOR MORE THAN 5+ MIN. I TURN IT OFF. I DON'T FEEL LIKE BREATHING ANY MORE DIESEL THAN I HAVE TOO. BUT THEN AGAIN, IF YOU LOVE THE SMELL OF DIESEL IN THE MORNING - LET HER RUN!

 

[GlennT]

There have been a number of postings regarding this in the past and after reading them, I have decided that if the tractor is going to sit unused for brief periods of time it is better to let the engine run than to submit the starter to the extra stress and wear of several restarts. However, I always idle my little John Deere at 1,300 RPMs so that there is adequate oil lubrication. A number of postings in the past indicated that there might not be adequate lubrication at 800 RPMs. When I start the tractor in the morning I let it idle at 800 RPMs for a minute or two so that the oil has had a chance to circulate throughout the system; then I increase the speed to 1,300 RPMs and I don't operate the tractor until the needle on the heat guage moves into the operating zone. This takes a bit of time so I usually take along my last early-morning cup of coffee and stand and admire the tractor and feel grateful that I have it. That green and yellow sure is a pretty color combination. By the way, when I finish work for the day and put the tractor in the garage, I decrease the RPMs to 800 and let the tractor sit for a minute or two until the needle on the heat guage drops to its lowest position before turning off the engine. I don't really know if all of this is necessary, but it's what I've gleaned from past postings. Even if I didn't do these things the tractor would probably run just fine and outlast me by many years; however, it gives me pleasure to feel that I am doing my best to take care of the tractor.

 

[BigE]

Most newer Kubota's will idle over 1000 rpm, they do this so they can meet air standards. This makes me believe there is something to the statement about unburnt fuel mixing with the oil.

 

[frank_f15]

i usually start mine at about 1000 to 1200 rpm and let it idle there till it warms up. when in use if i am off machine for more than 10 min. i shut it down other than that i let it idle at abot 1000. i don't think u can hurt it much either way, for the no. of hours most of us use our tractors.

 

[hayden]

I think this is an area rampant with myth and wive's tales. To me the most credible source of information available to most, if not all of us is your owner's manual. My recollection is that it says nothing about the hazards of idling the engine. It does specify an idle speed (at least in the workshop manual) and I think that's the speed the idle should be adjusted to.

Unless you are getting advise from a deisel engine design engineer from Cat or Kubota or Cummins or the like, I would question whether you have a source of advice more qualified than your manuals.

A couple of other things to consider:

If idling for extended periods of time were a problem, wouldn't the manual say not to do it?

When was the last time you had trouble starting your deisel?

 

[Anonymous Poster]

HAYDEN,I HAVE TO AGREE WITH YOU.THERE ARE TOO MANY PEOPLE THAT INTEREPT SOMEONE'S FEARS (OF SOMETHING THEY HAVE LITTLE KNOWLEDGE OF) AS A QUALIFIED STATEMENT OF FACT.(MYTHS & WIVES TALES) HOW MANY STARTERS HAVE YOU HAD TO REPLACE ON YOUR TRACTOR BECAUSE YOU STARTED IT TOO MANY TIMES. I DON'T IDLE MY CAR - I DON'T IDLE MY TRACTOR - SIMPLE

 

[jdkid]

Hi ya
as i recall both CAT and maybe cummins have come out about long idles at a low idle <1000 rpm diesels tend to over fuel and wash fuel passed the rings .also tends to build up carbon on rings etc etc short answer try to keep idle as short as pos or if not able too keep a fast idle going a new starter is cheeper that a early rebuild
catch ya
JD Kid

 

[Anonymous Poster]

Alright here we go with worrying about someones fears. Both Cummins and Cat in an article published in a Progressive Farmer magazine about 4 or 5 months ago very strongly advised that if you slow idle, only do it for 5 minutes. They advised that at the low fuel levels of idle that the engine temp went down and the unburnt fuel contaminated the oil.
They further advised that if you must idle, fast idle is the way to go, which some engine companies equip their equ. with from the factory.
This info is not my opinion or general views. This is straight form the companies that make diesel engines. If you want to argue with them go for it.
Greg H

 

[Anonymous Poster]

Avoid Idling A Diesel Engine...

<font color=blue>...They further advised that if you must idle, fast idle is the way to go... This is straight form the companies that make diesel engines...</font color=blue>

I agree, this has been widely published by these engine manufacturers... Besides being discussed at length in other sections of TBN {do a search}...Ex. this is from a John Deere Manual:

AVOID IDLING THE ENGINE

Allowing engine to idle at low rpm uses fuel inefficiently, and can cause a build-up of carbon in the engine.

If tractor must be left with the engine running more than three or four minutes, minimum engine speed should be 1200 rpm.

 

[Youare]

Being new to diesel engines I am glad you asked this question. I was under the misconception that diesel engines liked to run rather than be started and stopped like a gasoline fueled engine. When I found out that a new starter for a Ford 1710 I was considering purchasing cost over $500.00 I decided to try to extend the life of the strater in my Kubota by reducing the number of times I started and stopped it, let it idle.

I can idle my L3000DT as low as 800 RPM on the tach. After starting the engine I let it run at 800-900 Rpm for about 30 seconds then advance the idle to just over 1000 RPM. Any idle time is around 1000 RPM. I guess the price of a starter is much less than a rebuild.

Randy

 

[r0GuE]

Re: Avoid Idling A Diesel Engine...

Anybody know what the BX2200 idles at? It doesn't have a tach so I have to guess what its low idle is.

Rogue

 

[hayden]

I consider that a qualified source of information. Do you have a pointer to the article by chance? Sounds interesting.

 

[hayden]

Re: Avoid Idling A Diesel Engine...

Another qualified source of information.