RowJ

A lot of members have made up their minds about how to handle this issue. Most don't care for long idle times, myself included, because we don't need them!

What impresses me is this......
Of those that do have a need to idle a lot.... AND increase rpm's to 1100-1200 when doing so.... none of them have had problems!
I believe the pickup Cummins engine can take it with not bad side effects.

The other fact I find impressive came out of Alaska. Someone ran their CTD 24/7 through the winter and found idling at 1200 rpm only burns 1/2 gallon an hour!

RJ

Miles PH

Well it is the same Cummins as in big rigs and my Mackinac told me as long as I sit in my truck to leave it in neutral not pork it not hurt a bit ,I sit in neutral sum times as long as 12--15 HRS a day and not using moor than 1/8 of fuel With A/C or Heat on.The neutral thing has to do with transmission problems.

pearlbronze2500

The harvest company that i work for in the summer months never shuts the pickups down because it is so hot. I am talking 13-14 hours per day of idle time just sitting in a field. No high idle kits, or any aftermarket mods and I have never seen a problem.

Jfaulkner

These are from the manufacturers.

Cummins

Caterpillar

04ctd

jfaulkner is correct.

"cylinder washdown" is when the fuel is not burnt completely and causes damage.

the older trucks did not have a "high idle" and had this problem

the newer trucks have a "high idle" in the ECM that the dealer can enable.

they do not 'cylinder wash' at the ~1100 Rpm, and the Cat sticker says,

and can idle forever.

the accepted rule of thumb on here is 5 ~ 15,
less than 5 - leave running,
more than 15, shut it down unless weather, or kick on the high idle & let it sit.

to verify this, idle your truck - it won't heat up.
idle it with the high idle - it will heat up.

do a search, this comes up every ~6 months or so.

the tranny doesn't circulate fluid in park,
only in nuetral

of all the folks on here, i think only 2 have had problems with the tranny by idling in neutral. search for that, he had pics.

in other words, nothing to worry about.

some guy idled for ~6 months, search for a thread "who has idled the longest" or something like that.

Rsquared28

Yep, cylinder washdown - also leads to oil dilution from the unburned fuel running past the rings and into the crankcase. At idle, the rings do not deal well. Just not enough cumbustion pressure to make them seal against the cylinder walls. You will also get more oil burned because of the same situation. The rings can not seal out the oil properly. A good sign of this is what is called slobber, oil accumulations around exhaust manifold gaskets, manifold joints, and in the exhaust.
One interesting point apout idling is fuel economy. Caterpillar studied fuel usage in idling engines. They found that an engine left idling uses MORE fuel than one bumped up to 1100 RPM. The reason is the parasitic load of the engine accesories. Once the RPM exceeds ~1000 RPM, the parasitic load decreases and the fuel requested by the ECM lowers.

TexasCTD

I know this cylinder washdown thing comes up every once in a while. But, I have still not yet heard of a documented failure from idling a Cummins at any rpm for any length of time. Can somebody show me any documented proof of "cylinder washdown" or it's effects?

Personally, I don't have much need to idle....and I have a high idler anyway. But I wouldn't be afraid to do so for however long I needed it to.

RowJ

Will the Cummins manual count as documentation? See Jfaulkner's post above. IMO, that's good enough for me.... "combustion temperatures drop so low the fuel will NOT burn completely".
Thus...... "cylinder washdown"!

RJ

mx684

so it is alot better for them to start/shut off many times a day rather than leave running.....well that answers my question...i need to change my ways... i had been told it wouldnt hurt...and i know with my truck..if it sits shutoff in the cold for a while, (20's) or so...it turns over really slow and doesnt sound very good when it fires up...so i always assumed that wasnt good, so i just left it running...but i guess that theory was proved wrong, so thanks for everyones imput...last thing i wanna do is tear sumthing up and have high dollar engine work done..

TexasCTD

Rowland,

I don't doubt the possibility of it occuring. I read what JFaulkner had in his post. But what im saying is......I have been on this board for 2.5 years and I have NEVER heard of anybody having a problem with their Dodge Cummins idling short, long, or whatever. IF this was a problem you would think it would have shown itself among some of the members here.

TexasCTD

MX...if you haven't had any problems with it idling before....why do you think it would suddenly start having them now because you read this thread?

I wouldn't worry about it. Kill it if you want or let it run if you want. Personally, I think cold starts put more wear on an engine than letting it run. But then again, my climate is rarely very cold.....I plug in when I can...and I have a high idler.

Tate

I guess it depends on how long it idles vs. how many times you need to start. In 20 degree weather, my truck rarely gets plugged in. On some jobs, I had no option of plugging in, so I had to start it by itself in -15C weather. Take it easy on it till its warm. When you run it in that cold of weather, watch your EGT's. It won't take long, and it will be dropping below 300. If I start my engine and the heaters don't come on, and I don't give it any throttle, it won't get to 300 for a good while. Thats proof enough to me that it either needs to idle up, or get shut down. Which one I do depends on how warm the truck is, and how long its gonna be sitting for.

RowJ

Not necessarily, IMO.
It's one of the Do's and Don't that will NOT kill a Cummins.... but rather makes a difference when you get to 250,000 - 350,000 miles, and wonder why your engine is acting tired and worn out. Chances are, problems down the road will never be blamed on poor operating techniques.

Long idle time at low EGT's is comparable to going way too long between oil changes or perhaps, repeatedly working your CTD hard before it's fully warmed up. You may not have to pay for it now but ......?

RJ

dhughe2

Does this rule of thumb only apply in cold weather? what about when it gets into the 60s-100s?

crobtex

Look here for the Cummins Southern Plains support site. Most of the answers are pretty short and vague, but it gives you the general opinions of Cummins.