Extended idling vs switching on and off

[john_bud]

Most of the extended idle mentality is from old way of thinking on old engines. Old diesels are a pain to start and easier to just let run... Stuff like pony start dozers, tractors and big trucks.

But new modern diesel don't benefit from sitting there idling for hours on end. But hey it your money ur sending up the stack so idle to your hearts content. If its gonna be more than 5 mins at idle I shut it off.

My old diesel tractor is a 1963. Just idling it will cool off and start to white smoke bad. Then after about 20 min it will slobber out the muffler as unburnt diesel mixed with exhaust soot is coming out. Takes about 5 min of hard work to heat up enough to stop smoking and another 15-20 to clean out the muffler.

Well a story told to me by a trucker in the late 80's was that the company was b*****ing at them about leaving the tractors running overnight as they slept in New England winters. (Low temps and happy truckers don't match up.)

So one of the truckers, who was also a mechanic, rigged up a five gallon gas tank to the fuel line with pictures and everything and idled it overnight. It used about a half-gallon of diesel. The next night he reset the setup and stayed in a motel for the night. He went out in the morning and started it up. It took about 3/4 gallon of diesel to start it up.

He then made a package and sent it to to the dispatchers and several others up the chain. After that they were allowed to idle overnight.

Like I said this is a story heard in passing, way back when. Nothing to back it up, but it seemed believable at the time.

Sorry, but this "story" is 100% total complete bs. Somebody sold you a bill of goods on it!
Just think about the start up you list. 3/4 of a gallon to start. It takes 1-3 sec of cranking to start a diesel engine when cold. If it's 3 seconds of cranking, it is pumping a quart of fuel per second. that's 60 quarts a minute or 15 gallon per hour. A typical gas pump runs 7 gal a min. A typical garden hose runs about 5 gal a min. The fuel injectors would have to put out a stream of fuel of truly heroic proportions. By the way, if it actually did put out that much fuel, the cylinders would hydrolock.

The idle consumption of a big diesel is also about a half gal per hour at low idle and up to 1.5 gal per hour at high idle. According to Cummins.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0CDwQFjAD&url=http%3A%2F%2Fcumminsengines.com%2Fuploads%2Fdocs%2Fcummins_secrets_of_better_fuel_economy.pdf&ei=UO4wU8qWJoSNygGB1YG4Aw&usg=AFQjCNGuRpwrv1HIULfq3W0jHzsRph-wjA&bvm=bv.63587204,d.aWc

 

[sd455dan]

i let stuff idle all the time. i dont let the tractor idle for an hour for no reason, but i will idle 10 min, use for 5 min, idle for 10min, etc. its a utility diesel engine that uses negligable amounts of fuel to idle itself. i do not, and will never buy into the "cylinder washdown" theory, but people sure do love to throw that around. remember in the "old days" when equipment and trucks used to idle for hours and hours/days and days if necessary. i dont think there were too many 71 series detroits, 3406 cats, or even smaller equipment suffering from the terrible cylinder washdown. the things are made to run, and that is their only function in life. ideling is easy

yep - the guys running the train engines let those idle at the local switching area- sometimes for days and days....never saw any white smoke after all that time either...

 

[Jkott]

Well a story told to me by a trucker in the late 80's was that the company was b*****ing at them about leaving the tractors running overnight as they slept in New England winters. (Low temps and happy truckers don't match up.) So one of the truckers, who was also a mechanic, rigged up a five gallon gas tank to the fuel line with pictures and everything and idled it overnight. It used about a half-gallon of diesel. The next night he reset the setup and stayed in a motel for the night. He went out in the morning and started it up. It took about 3/4 gallon of diesel to start it up. He then made a package and sent it to to the dispatchers and several others up the chain. After that they were allowed to idle overnight. Like I said this is a story heard in passing, way back when. Nothing to back it up, but it seemed believable at the time.

It's beyond BS. My duramax can't idle for an hour on a half gallon of diesel. No way can a semi do it overnight. A half gallon of diesel has 64,000 btu of energy , assuming 100% efficiency. The electric block heater alone takes 34,000 btu to run for 12 hours (assuming the drivers off time) and it can barely keep the block warm, let alone the cab. There is no way it is physically possible to keep the engine running and warm, as well as heating the entire living quarters, with a half gallon of diesel. There is a reason that truck stops invented docking stations with power and heat/cooling. The smaller engine is simply in efficient at idle when compared to an electric power plant running in its efficient range.

Now if you told me it only burned all 5 gallons overnight, then I'd be impressed.

 

[RoyJackson]

yep - the guys running the train engines let those idle at the local switching area- sometimes for days and days....never saw any white smoke after all that time either...

I have read those locomotives are left idling (when they're not working) 24/7, 365 days a year, except for maintenance shutdowns.

 

[Tx Jim]

So one of the truckers, who was also a mechanic, rigged up a five gallon gas tank to the fuel line with pictures and everything and idled it overnight. It used about a half-gallon of diesel. The next night he reset the setup and stayed in a motel for the night. He went out in the morning and started it up. It took about 3/4 gallon of diesel to start it up.

REALLY only 1/2 gallon of fuel to ""idle the engine all night"" but 3/4 of a gallon just to start an cold engine???? I bet that trucker that performed that test was smoking some WACKY T-BACKY

 

[Blade Breaker]

Now with all this talk of diesel engines and extended idling no one has mentioned any failures or break downs because of idling. And would it make sense that "today's new engines" with the fuel injection technology compared to the old injection pumps would run much leaner at idle and have less tendency to have issues? I have had the same experience as john_bud on some older engines running rich or loading up when idling for a long time. Never any problems other than some smoke for a few minutes.
Everyone should do what they are comfortable with but I have a hard time believing that you could damage a diesel engine letting it idle.

 

[PapaPerk]

Now with all this talk of diesel engines and extended idling no one has mentioned any failures or break downs because of idling. And would it make sense that "today's new engines" with the fuel injection technology compared to the old injection pumps would run much leaner at idle and have less tendency to have issues? I have had the same experience as john_bud on some older engines running rich or loading up when idling for a long time. Never any problems other than some smoke for a few minutes.
Everyone should do what they are comfortable with but I have a hard time believing that you could damage a diesel engine letting it idle.

My Dodge Cummins manual says don't idle for extended time. I believe Cummins.

The engines will never warm up at idle in colder temps. Even with auto idle up mine will never reach operating temp idling.

 

[Blade Breaker]

My Dodge Cummins manual says don't idle for extended time. I believe Cummins.

The engines will never warm up at idle in colder temps. Even with auto idle up mine will never reach operating temp idling.

I believe cummins also. But I also am confident that it has more to do with the dpf filter than oil dilution or any other problems. The emissions is the big problem with "today's new engines".
Strange it does not warm up. My friends cummins is very good here in mn. Also my Ford warms up nicely idling.
I was only wondering if anyone has had any real problems with extended idling? Never heard of any myself.

 

[PapaPerk]

I believe cummins also. But I also am confident that it has more to do with the dpf filter than oil dilution or any other problems. The emissions is the big problem with "today's new engines". Strange it does not warm up. My friends cummins is very good here in mn. Also my Ford warms up nicely idling. I was only wondering if anyone has had any real problems with extended idling? Never heard of any myself.

What is dpf? Mine is a 2004.5. Only emission control it has is a cat.

 

[dave1949]

I believe cummins also. But I also am confident that it has more to do with the dpf filter than oil dilution or any other problems. The emissions is the big problem with "today's new engines".
Strange it does not warm up. My friends cummins is very good here in mn. Also my Ford warms up nicely idling.
I was only wondering if anyone has had any real problems with extended idling? Never heard of any myself.

Who's is going to idle their engine for long periods to see if they can cause a problem? Not me.

If habitual and lengthy slow idling shaved some, say 20%, life off of your engine, how would you know?