I periodically read a thread that relates to an engine that idles too frequently ( an unknown amount of times ) and not run at highway speeds is not a good idea. But .... I never read the mechanical reasons why. I usually start and let my Cat 400HP run for 30 minutes every 2 weeks. Mostly the thread answers are: it's the oil that doesn't have the ability to lubricate correctly or something relating to ???? Anyone have the facts? Just the facts Mam, as Sargent Friday would say.

2ndhom wrote:I periodically read a thread that relates to an engine that idles too frequently ( an unknown amount of times ) and not run at highway speeds is not a good idea. But .... I never read the mechanical reasons why. I usually start and let my Cat 400HP run for 30 minutes every 2 weeks. Mostly the thread answers are: it's the oil that doesn't have the ability to lubricate correctly or something relating to ???? Anyone have the facts? Just the facts Mam, as Sargent Friday would say.Diesel engines will not reach operating temperatures when sitting at idle.Most diesel vehicles have the ability to raise the idle of the engine by using the cruise control. Even my F350 Power stroke engine will automatically raise the idle if sitting still and in park (the ECM does it). My American Dream has the ability to raise the idle with the cruise.If you are starting your engine so that it does not sit all winter the 30 minute time range is ok, but raise the idle to 1200. Other wise it is best not to start it.

Your engine will not get up to operating temps. This is very hard on the injectors for one. The colder temps inside the combustion chamber cause the fuel to cause build up on the tips and also to sort of sand blast them as the cold mixture swirls around them which greatly expedites wear.Your much better off letting it sit than idling for it 30 minutes.

When I started driving semi's I was taught that when you idle a diesel engine the oil pressure is too low for an extended idle. Tearing engines apart after drivers idled to sleep, it was found that a lack of oil pressure did most of the idle damage. By bumping the RPMs up 200 or 300 it raises the oil pressure to better lubricate the engines component. The engine will also run closer to normal operating temperatures. The "high idle" function of the cruise control serves this function. Turn your cruise control on and bump the accelerate button. The RPMs will come up to 900-1000 RPM. Turn off the cruise control or press the brake peddle to drop RPMs before you turn off the engine.It is not needed to start and idle the engine every two weeks for 30 minutes. Unless you plan to drive it just let it sit. Put a battery charger on it if required but running it at idle will not get it up to temperature and can harder on the engine than letting it sit. Farm engines sit for months between use.

Do NOT start your engine every two weeks and just let it idle, even high idle.All you are doing is adding moisture to the crankcase.If you start it, drive it at least 25 highway miles-- enough to get the oil, not just coolant up to operating temperature. This advice is from both Caterpillar Corp and Cummins Corp. Has not changed-- has always been this way.And, yes, with 2007 and newer engines, idling clogs up the DPF (Diesel Particulate Filter). They are much more sensitive to long periods of idling than previous engines. Doesn't matter what engine brand.

A Diesel at Idling RPM’s ....... | Good Sam Community

32 Replies

427435
Explorer
Feb 03, 2014
PatStab wrote:
I overnight in truckstops sometimes and I can tell you all the trucks around me are running all night long. I will run my generator figure its no louder then their trucks. Not sure what they are doing about these issues as their trucks are idling.

You may have been hearing their auxiliary diesel power units.

http://www.truckgenerators.com/
wolfe10
Explorer
Feb 03, 2014
Another thread with a confusing combination of "best practices" and "what I got away with".

Everyone has to/gets to choose which path to follow.

The engine manufacturers have all outlined the same "best practices".
BigRabbitMan
Explorer
Feb 03, 2014
PatStab wrote:
I overnight in truckstops sometimes and I can tell you all the trucks around me are running all night long. I will run my generator figure its no louder then their trucks. Not sure what they are doing about these issues as their trucks are idling.

They are drivers and not owners!
PatStab
Explorer
Feb 03, 2014
I overnight in truckstops sometimes and I can tell you all the trucks around me are running all night long. I will run my generator figure its no louder then their trucks. Not sure what they are doing about these issues as their trucks are idling.
427435
Explorer
Feb 03, 2014
As for a diesel truck idling at a truck stop, it came in well warmed and will go back on the road and worked for several hours when the driver gets back in. That's a big difference compared to starting a cold engine, idling it for a while, and then turning it off.

Leaving it sit will be much better for it. Diesel construction and farm equipment sit for months without starting with no noticeable harm.
RVUSA
Explorer
Feb 03, 2014
wallynm wrote:
Because I have it ready every time we get engine service and then ask if they see anything we should be doing differently [qu

ote=RVUSA]
wallynm wrote:
I can not convince you as you need to go talk to the service manager of your local franchised Cat repair facility. I can tell you that they can read how much time you let it idle by reading the ECM. Ask me how I know.

I'll ask, how do you know that Wally?

Oh. I was half expecting some long drawn out "They are watching you and I lost my warranty" thing. LOL
wallynm
Explorer
Feb 03, 2014
Ask them to read your ECM
2ndhom
Explorer
Feb 02, 2014
OP here .... an abundance of excellent reading, advice and experiences not only from the fellow RVer's but diesel truck drivers also. Lots of information as food for thought. Thanks all!!
wny_pat1
Explorer
Feb 02, 2014
down home wrote:
Semis ran/run million miles before major overhaul of engine. They idled at truck stops etc to keep the Drivers warm, or cool, in summer.
Never did the engines any harm. The newer emissions diesels, I dunno.
Not any more!! Today, idling at diesel can get you fired, and the trucking companies can check the computer to see exactly how long you idled the engine during your run. The trucking companies don't want them idled and the engine manufacturers frown on it. Plus is is against the law in many states to idle your diesel a specified length of time, depending on the particular state. And it did harm way back in the times you are talking about. Us old time truck drivers never "idled" our engines all night to keep warm or cool. We always bump up the throttle to between 1200 to 1500 RPM, and that is a high idle where less damage is done. Heck, truck stops sold Throttle Sticks back them, and still do.

You wedge it between the pedal and the bottom of the dash. The adjustor slides up and down the rod to adjust the RPM.

In fact, the trucking companies don't even want you idling to warm up the engine in freezing cold weather. The say the new diesels with computers compensates and adjust for the cold temperatures and as long as you don't put the engine under serious pressure, every thing is good. Just start up, build your air pressure, take off and go, but don't horse it until she has warmed up. The computer takes care of everything.
JimM68
Explorer
Feb 02, 2014
The moisture issue would concern me the most. Things that are heating up cooling off in cold weather will attract and then condense moisture.

If you are going to run it at all, you need to run it hard enough and long enough to burn off all the moisture out of the crankcase and the oil.

This is not generally an issue with truckers, that engine was hot when it pulled into the truckstop, all the moisture was long since cooked off.

Your RV's diesel (including the diesel genny)are 100% happy sleeping quietly all winter long.