My understanding is that once the temp needle is in the normal zone, the engine is sufficiently warm for complete combustion of the fuel/air mixture. I can't see why incteased idle of a fully warmed up engine is necessary, especially in those heat wave States where daytime temps are approachin 100F.

On the other hand, prolonged idling wastes fuel, which is a valid concern. I find my truck's AC does a pretty good job of cooling things down quickly, in any event.

 

I've been towing cars around the country all summer, and I only use the starter on my truck once per day. It starts up in the morning and it does NOT shut off until I am done for the evening. This means running the thing for 10-14 hours continuously per day (depending on how much driving I'm doing). It idles at the gas station when I fill up, it idles while I'm getting my lunch, and it idles while I'm loading/unloading cars (loading especially where I need it to generate the power for my winch to load up defunct cars). This CAN mean idling for 30 minutes or more. Furthermore, this is the practice I have always had with the truck.

The results (at the moment, at least) speak for themselves: 52,000 miles, NO PROBLEMS! Not a single injector issue, the engine has only gotten stronger with time. Runs better and gets better fuel mileage than it did when I drove it away from the dealership with 24 miles on it. Also, I'm going to idle my diesel ANYWAY. In the hot weather, I want my truck to be nice and chilly when I get in, and in the winter I want it to be nice and hot when I get in! Besides that, my bunny rabbit who travels with me doesn't want to get cooked alive in my truck from letting it sit with no AC.

My counterpart in name (Ted aka Dr. Diesel) is correct in what he says. That said, this engine can take it, as can most. New York City is proof that you can idle your car for hours on end and the engine will still last. Take a look at all the Crown Vics, Lincoln Town Cars, etc. that are idling either while the cops are eating donuts, or the taxi drivers are eating lunch, waiting for a call from the dispatcher, etc.. However, to those who do have injector problems, I will reiterate what I've said before: USE YOUR TRUCK! It is not a Toyota Camry, so don't treat it like one. Hook up a 10,000 lb trailer and go 70 mph! I personally believe that this is the reason why people are having injector problems... too many people buy these trucks because they need to tow something a few times a year or just because they like it. If you need a Camry, buy a Camry. These trucks are happier with a trailer attached than without, and I think that it's this prolonged period without getting the cylinder pressures and temps high due to heavy load that kills the injectors.

But hey, what do I know...

 

Kudos Ted I agree 100% !!!!!! This idling thing has too many people thinking they WILL destroy something if they let them idle for more than 2 minutes . After driving ready-mix trucks for 10 years I can tell you those beasts spend more time idling than they do driving and injector probs were few and far between . DC has used that bs excuse so many times that everyone is scared to death of letting their truck idle . I let mine warm up before I leave and she idles alot, no probs here at 20,000 miles now . Too each their own it's YOUR truck do what you please but remember that engine is pushing 17 : 1 compression and startup is the hardest on these engines with 0 oil press .

 

Poor quality fuel in general and maybe growing pains on injector design.I went through the entire same process and at times even words and statesments about this issue in 1975 through 1983 with EFI on autos and with Bosche injectors.Once the FUEL quality caught up and injector design changed there was no more problem.But it was not the IDLE time causing the problem.From what I've read WE(U.S.)have really poor qualiy diesel fuel compared to Europe.

 

Quick response to kayjh... When the engine runs loaded it will reach max coolant operating temp and develop the optimum 1000*F cylinder ignition temp AT TDC compression point for complete combustion... true... but then when allowed to idle, even tho' the thermostst may (or may not) hold the coolant at max 200 or whatever... the cylinder temp at TDC ignition point will definitely go down resulting in less complete combustion, some unburned fuel, and cylinder wash of lube oil... this is not just aimless theory... In my tenure as a field test engineer on customer fleets, I have actually installed thermocouples adhering to cylinder head fire decks and watched the cylinder temp a the compression chamber cool down and at the same time measure the exhaust particulate increase (unburned fuel)... IDLING KILLS ENGINES!!!!...

Rest assured for those of you who think you get wonderful engine life when idling a lot, engine life would be even MORE WONDERFUL if you minimize idle...

The REAL problem is IDLING a Diesel has assumed a BIG MACHO TRUCKER GUY IMAGE... and its "cool" to slip down from your cab and STRUT away from the rattling ragburner... Many professional truckers, however, are showing their brains and shutting down... but just as many still let 'em idle... and ..."Now that WE have ragburners in our pick-ups, we can be MACHO TRUCKERS at the 7-11 and Mini-Marts too"... I ABSOLUTELY KNEW my post above would attract some die-hard argument... and I'll end it here knowing that for every one of you in denial, there are five listening and abiding by the advice to SHUT 'EM DOWN...

The one forgiving factor that we didn't have a few years ago tho' is the electronic fuel management... Our electronics really lean out the fuel charge at idle to greatly reduce the volume of unburned fuel we had with the traditional mechanical fuel systems... The most obvious example of this is the virtual elimination of WHITE SMOKE at COLD START-UP on today's electronic engines... whereas the former old mechanical engines at cold start-up would belch white smoke... actually unburned fuel liquid droplets that in a newly started cold engine don't even get hot enough to turn black....

Congratulations to the guys who listen... signing off... no more time to argue against an impenetrable brick wall...

Cheers... Ted

 

I agree with Ted (tdupuis). These cummins have millions of logged mileage with them sitting overnight at truckstops just idling with no problems. I myself have spent many of nights in them with the A/C, Heater running and never had any problems. In the summer time if its hot, I don't shut my truck off if I'm traveling. Its sat and idle for 30-45 min @ a time.

 

Dr Diesel, When I go in a 7-11 I leave mine running as I am only going to be under 5 minutes. I dont try for a 'Macho Trucker Guy Image' and I doubt that the others on this thread do either.

Of course you wont be reading this post as you dont have the time as you stated.

 

How many gallons will a truck burn overnight idling? Our size and semi's? Just something Ive always wandered. Thanks, George

 

i'd have given him a break, perhaps he didn't have a phd

i let mine idle all the time when its hot, he could have been running the A/C or letting it cool down. you'd have had a lot of truckers to call out in western OH yesterday with the heat index of 108. fortunately my A/C was broken in the big truck so i was able to be in compliance.

 

I heard somewhere maybe the *********** that one hour of idleing burns 35miles worth of fuel. so for most of us that is about 2 gallons per hour idleing!!! I currently have 170 hours of idleing on my truck and have burnt somewhere around 250 gallons of fuel according to the computer!!!

 

Dr Diesel I do the same thing with this truck as I did with my 99 chevy gasser.It has nothing to do with being macho letting it run when i go in a quickshop.It has to do with keeping the ac on or the heat or not abusing the starter.Look on your visor it says something about letting it run to recharge the batteries after you start it when its cold because of the grid heater.So if i take your advice and i run up to the store to get something I should shut it off if I am only going to be in there for 5 min.Will my batteries be recharged?????????? I was not going to be a smart *** but I thought about your second post!!!!!!!!

 

you lost me with that one

 

That is false... it's closer to 1 gallon per hour. I seem to recall a number of .8 gal/hr on the 24v 2G trucks per an email from cummins... but that was a long time ago, hard to remember for sure. That is with the truck in park or neutral. If you leave it in gear with the e-brake on you'll burn more fuel, which is what I did in my '99 if I wanted to idle in the cold. With the '05 I just bump it up to 1200rpm and call it good. If I can find the exact reference for idling GPH I'll update this post...

edit: couldn't find the email I was looking for, but this thread seems to indicate an idling consumption rate of about .4-.6 GPH at idle... and about 2-3 times that if the auto tranny is in gear. Keep in mind this is a 2nd gen, but I can't imagine the 3G using that much more at idle, even with the 3rd injection event wasting some.

 

I for one DO prefer to walk away with a "BIG MACHO TRUCKER GUY IMAGE".

Diesel, M.D is kinda taking the topic to heart don't ya think?


I idle for the same time frames and same reasons that EVERYONE ELSE does.
Ever heard your CTD shut off after about a 5 mile ride in the dead of winter? Sounds like it may never start again (abrupt jerk and halt? maybe normal, but I don't like it)
The Poor guy at the 7-11 could have came from his house a half mile down the street, I would idle it too!

 

There are two worlds that we can live in.

The world of labratories and theory.

The world of "where the rubber meets the road".

I live in the second world and let my Cummins idle.