Long idle periods

[CPittman]

I leave my truck idling for extended periods (30 mins at a time - maybe 4 times a day) while on the job... mainly to keep the cab cooled. I've heard of cylinder 'wash-down' happening during extended idle. Should I shut it off, or just add Stanadyne and idle away?

 

[Dean Upson]

That much idling is not a good thing, do a search here and you will find this subject has been covered before. My advice would be to shut it down when you are going to be out of the cab for extended periods.



Dean

 

[Jeremiah]

Shut her down

Owner's Manual says shut 'er down. Others say it's worth shutting down at stop lights if you're gonna sit there longer than two minutes. And if you've got an automatic transmission, it's a good idea to shift into neutral.



Same goes for a 6-speed too. Don't sit there with your foot on the clutch. Put it in neutral and let out on the clutch until it's time to go. The clutch will last longer that way.

 

[Jeremiah]

Does a bear do it in the woods?

Originally posted by Dean Upson

That much idling is not a good thing, do a search here and you will find this subject has been covered before. My advice would be to shut it down when you are going to be out of the cab for extended periods.



Dean

Hey, Dean, just heard a loud noise in the garage and went out to see if my truck wanted to go somewhere. It was a big brown bear poking around looking for something to eat! Figgered it might be a good way fer whoever it was wanted to keep that cat off his truck. I looked around after the bear was gone and didn't see a cat anywhere.

 

[gsbrockman]

30 minutes is a little too long to leave running, but I don't think you'll be experiencing significant cylinder wash-down in Texas with the a/c on. I was under the assumption we needed to worry about wash-down on a cold engine (even if the block heater was used) in the winter with cold ambient temperatures. If it were me, given the cost of fuel, head back out to your truck 10 minutes before you leave and fire up the a/c... ... you might want to look at some Ventvisors and crack the windows, unless you're in a dusty environment.

Greg

 

[Tony T.]

Ideling

Shutting down would be the best of all for the engine longevity I think. If that's not going to work for you I would consider changing your oil an filters a lot more often than what the owners manual calls for in schedule B.

 

[GFritsch]

Rig drivers run their Cummins engines all night. What could hurt this engine by idling ? As long as the engine is at operating temperature it seems to me the only harm would be normal wear and tear of time running.



Haven't heard any specific reasons for damage. That being said it seems silly to run a truck for 30 mins just to keep the cab cold. The truck cools down fairly fast with windows down and A/C full.



I personally would not worry

 

[Jeremiah]

GFritsch, rig drivers aren't the best judge of what's good for an engine, especially if they don't own 'em. Plus, there aren't that many rigs out there with Cummins engines. These drivers prefer Cats and Detroits, or so I am told. I'd stick by the owner manual that suggests not idling an engine longer than a few minutes.

 

[GFritsch]

Still... .



What is the cause of damage? I am not saying there may not be a good reason, but I have never heard it. The main seems to be the engine gets cold. The t-stat should keep the engine hot in most conditions. Anything else?



If Cats and Detroits are O. K. to idle and not Cummins why? At 50mph in last gear the engine is doing little more than idling with a lot more cooling.



Any Diesel techs out there that can explain why it might be bad.

 

[XJSuperman]

Why not set it at high idle? If the engine is turing at 1,000 RPM's it's more likely to keep temps up and not wash down the cylinders (if that is indeed a problem). Seems like the engine would be working harder at 1000 but other than burning fuel I don;t see what it would hurt.

Just a thought.

 

[JLovas]

I'd also say let her run...



In ag, our Cummins engines start in the morning, run all day long, and get shut down at night. To me, that is the perfect scenario for a diesel engine, rather than multiple start and stops throughout the day that works best for gasoline engines.



Up here, in the winter, alot of trucks (semi's) get parked at 5:00 p. m. Friday, and idle all the way until Sunday night or Monday morning, so they're looking at 45-60 hours of idle time every weekend. (This is so the tank heaters will keep the #2 fuel from gelling up). So I don't think 30 minutes is going to hurt. Just stay on top of your schedule maintenance and and don't sweat the small stuff.

 

[yogibear]

I've idled mine for 4 to 5 hrs. in winter with the E Brake on, and the temps stay at 190+*, no problems, and thats at regular idle rpm. In the summer at 75 - 80* with the A/C on it will do the same. 157K on it now, and no fuel ever in the oil samples. Did the same with my 00.



Larry

 

[sschu600]

WARNING:



Extended periods of engine idle may reduce average rebuild time of a Cummins engine from 350,000 miles to 325,000 miles. Beware.

 

[thejeepdude]

30 minutes at a time is nothing. When Cummins was asked about the prolonged idling causing cylinder wash down, they basically said that if it's hot enough outside and there's enough load on the engine to keep it warmed up, don't worry about it. The only thing you should be certain to do after extended idling is not shut it down immediately, but drive it around a bit to heat things up before you shut it down... personally, I idled my 2G 24V for hours at a time with the e-brake on and the transmission in gear in some cooold temps and never had a problem. I guess it's a decision each owner needs to make about how to take care of their truck. I think the extended idling statement in the manual was made to prevent ignorant owners who don't know what to watch out for from trashing their engines.

 

[CumminsBu]

Originally posted by sschu600

WARNING:



Extended periods of engine idle may reduce average rebuild time of a Cummins engine from 350,000 miles to 325,000 miles. Beware.

And Bombs won't?



What Happens When You Let an Engine Idle?



When a diesel engine idles for prolonged periods, the engine oil becomes contaminated more quickly than when the vehicle is being driven. Oil contamination is more prevalent in diesel engines because of the large amount of intake air used in the diesel combustion cycle. When idling at low rpms, the excess air in the combustion process cools the cylinder liners, resulting in incomplete combustion and condensation of unburned fuel on the cylinder walls. These deposits are eventually drawn into the engine sump where they contaminate the engine oil and reduce its effectiveness as a lubricant.

Idling at high rpms (1000 rpm) increases cylinder pressure for more complete fuel combustion. We do this on the diesel engine on are ships to prevent carbon build up in the exhaust also.

 

[CPittman]

I do change the oil about every 3 - 4K miles because it does sit idling for long periods AND it runs from 7 a. m. to 7 p. m. almost every day.



My original concern (I didn't think about oil contamination) was lubriation of the lift pump - that's why the question about Stanadyne.

 

[Bouncy]

I have always wondered about the idleing issue. I see semi-trucks idleing all the time at night.



One of the reasons I got a diesel was to sleep in the truck on a long trip. And I want to idle it to keep heat/AC running.



I have idled mine once so far for 1. 5 hours and it runs fine.



It was 15 degrees out and I had the heat running. When I parked there, the temp on the truck was 195 but when I woke up, it was in the 145 range.

 

[Jeremiah]

Idling

I had too much to drink one night and went to sleep, leaving my 1990 Honda Accord idling for 12 hours. Got up the next morning and drove off like nothing happened. It got 10 mpg just sitting there running. The car had 334,000 on it when I finally sold it and bought another one. Don't drink anymore either, so that's good.

 

[thejeepdude]

Re: Idling

Originally posted by Jeremiah

I had too much to drink one night and went to sleep, leaving my 1990 Honda Accord idling for 12 hours. Got up the next morning and drove off like nothing happened. It got 10 mpg just sitting there running. The car had 334,000 on it when I finally sold it and bought another one. Don't drink anymore either, so that's good.

This isn't really relevant, since a diesel engine idles a lot colder than a gasoline engine. Nice story tho.

 

[kstehnacs]

Read symptom/condition of tsb18-019-01. DC didn't come out with the cold high idle flash for no reason.