Is it bad for the engine to leave it idling for a long time?

Hi Gang,
We're in Vegas and my outdoor thermometer reads 110.8.  I'm in a very nice but shade-free RV Park and my temperature in the motor home is 76.1.  How am I managing a 34 degree difference?  Needless to say, the coach A/C is running non-stop, the shades are all closed, etc.  But with that alone, I could expect the coach to reach the low 90's by mid-afternoon (It's 11:30 A.M. as I write).  My ingenious (if I do say myself!)solution?  I bought a small fan, and I am running the engine so I can turn on the dashboard A/C (on high of course) and direct the vents to the point between the seats where I have placed the fan, which then sends cool air through to where we spend our time.

I don't run the engine constantly, but perhaps 1/2 hour on and 1/2 hour off, between about 11:00 A.M. until 6:00 P.M.  The sites here are spacious and I'm quite sure the exhaust isn't bothering anyone (If it was, I would stop doing this, of course).  What I am wondering is, am I doing any harm to my engine?  All the gauges have remained dead center (temp, oil pressure, etc.) and after several hours, the fuel gauge hasn't budged.  This is a temporary thing, in a few days we leave here and do not expect to be dealing with these extreme temperatures very much in the future.

And by the way, it's a Ford V-10 Triton engine.

Do any of my more technically-savvy friends out there have any comments?

Thanks!  And I hope you all are staying cool, one way or the other!

If the engine was a diesel, I would say that's very deleterious.  Gas - I don't know.  From a neighbor perspective, I'm glad I'm not parked next to you.

As I said, if there was any chance it would bother anyone, I would not do it.  It's 106, no one is outside, no one has a window open, it's a wide site, the wind is 13mph and gusty, I walked around the MH and there isn't the slightest smell of exhaust anywhere, even close to the exhaust pipe.  As always, I acted with diligence before going ahead.

I take being a good neighbor and a respectful fellow RVer very seriously, John. 

Sounds like you're very aware of being a good neighbor - that's a good thing  .  In further thinking about your situation, I would be more concerned about heat buildup in the engine compartment, or along the exhaust system.  Emergency vehicles are specifically designed or modified to idle for long periods of time, with a regular vehicle, I would be concerned.

As long as the gauges are normal, I don't see a problem on a gas engine. A diesel would likely get hot and build up internal sludge, so I would not do it with a diesel unless I used a high idle (about 1000 RPMs). And the diesel is louder.

Mid 90's by afternoon? Wow! We've been in 105 and full sun and ours gets to about 80-82. I thought that was bad enough. That was further north, though, so maybe the sun load wasn't quite as bad.

spend more time in the casino,

This is a very good question....

Several years ago I recall, gasoline engines, if you let 'em idle for too long things got a bit grunged (Plugs fouled and such) because the fuel mix at idle tended to be a bit rich, Overheating was an occasional issue.  Things like that.

Today's computer controlled Gas engines are less (FAR LESS) prone to that kind of thing.. So, Click and Clack (The tappit brothers) (Car Talk, on PBS) say it's ok to let modern Gas engines idle for long periods of time.

On the other hand... I recall reading a book where the author wrote that since the boat was a Diesel it was ok to let the engine idle ..  Ready for an instant get-away....

But the same brothers.. said not to do that with diesels.

NOW:.. I know for a fact they are not infallible.  I have heard them give wrong advice ONE TIME that I know of. But... I still they usually are right.  (Even in the case I know of they fixed the lady's problem..... But.... I could have done it for a whole lot less money.. Have in fact, 5 times)

One of the biggest reasons not to idle a diesel is called "diesel wash".  Modern diesels run very cold. Without sufficient heat in the combustion chamber the fuel does not get throughly burned.  That results in the unburned fuel "washing" the sides of the piston sleeves of the lubrication that is necessary to keep the piston rings sliding easily.  That friction causes early failure of piston rings and premature and excessive scaring of the cylinder walls. 

Yep, don't idle a diesel for more than 5 minutes at a time, or the consequences could be costly.

Sarge

SargeW said:

Yep, don't idle a diesel for more than 5 minutes at a time, or the consequences could be costly.

Click to expand...

Trucks in Canada, especially in the Arctic might not ever be shut off other than for oil changes and maintenance between November and March.    In southern portions of Canada there are many idling diesels at night in the truck stop parking lots.  Mind you one uncle is running some kind of diesel fueled bunk/engine warmer to save on diesel.

This thread makes me wonder: It used to be that over the road truckers would idle their engines for long periods, sometimes for hours on end, at truck stops and some other places. So what has changed in diesel design/construction to make it now a bad idea (from a maintenance viewpoint).

I worked with a GM engineer who told me that his test vehicles for engine wear were the cars that drove around the factory for deliveries. They were always idleing and produced the most engine wear.  His explination was that when an engine runs slow the parts are not allowing the fomation of a full fluid film between the metal surfaces therefore there is metal to metal contact.

Of course he was an engineer in the 70's so who know how the engines and oils have improved since then?

Are you trying to get 300k out of the engine? If not, then you may just want to be sure that your oil is clean.

One caution for this discussion: "idle" and "fast idle" (about 1000 RPMs on most diesel engines) are not the same in terms of wear and lubrication concerns.

I've seen (or rather heard) truckers run their engines all night when its cold to keep the cab warm. Have always wondered about that in light of the numerous warnings about long idle times. On the other hand, truckers are human and can err too.  Just because they do something doesn't make it a good thing.  Besides, if my choice was freezing my butt off or causing some extra wear on the engine, that engine is in for a rough night!

When  the company i was working for bought 100 ton cat quarry trucks [middle to late 80's i guess] they told us to go ahead and shut them down for breaks and lunch..........in years past we were told to leave them running from start of shift to end.......???

We just figured it was a fuel saving measure.......and the fact that all the new equipment started just like any car........made it a lot easier

i once contracted the road work in subdivision after i retired............they had an old cat road grader that nobody could figure how to start..........it had a gas pony motor......... .........when it was started it never shut down till the job was done........ ......i suppose it is still sitting where i last parked it when it finally wore me out.. ;D........nobody else dumb enough to run it...

I used to have several uncles in the long haul trucking business. That was the popular belief at that time that idling a diesel was better for it than shutting it down. Most likely the reason was that diesel fuel used to be a lot different formula than it is now.  Not long ago when the industry went to LSD (low sulfur diesel) mechanics and owners screamed that the lubricity in the fuel was so low that it would ruin their engines.  Now we have USLD which is even lower in sulfur.  The chemical make up has changed dramatically in the last few years. Gary is right about fast vs slow idle.  A faster idle will heat the engine block and allow the fuel to completely burn.

Letting a diesel lope along at 500 to 800 rpm is not fast enough to generate the heat necessary to completely burn the fuel. Gas engines are a different animal.  Spark ignition burns much hotter and with the technology of modern engines, many can idle for hours with the biggest problem may be a slight fouling of the spark plugs. But with the computers on modern engines when the engine sees the reduced need for fueling a computer leans out the fuel mixture.

Most truckers these days have modern cab heaters to stay warm and don't rely on the engine to keep the cab warm when they are stopped. It doesn't mean that some still  won't idle the engine all night anyway. It's their buck, and their truck. And the same can be said for the RV owner.  It's their rig so do what they want.  It's just a good idea to do a little research and learn about the technology your rig. Any of the engine sites like Cummins or Cat will have info available as well as many diesel truck enthusiast web sites like the TDR.  It's all info out there for the reading. 

RV Roamer said:

I've seen (or rather heard) truckers run their engines all night when its cold to keep the cab warm. Have always wondered about that in light of the numerous warnings about long idle times.

Click to expand...

My Brother, who is an over the road truck driver, has found the perfect solution to that problem

He runs his HONDA EU-2000i all night, the electric space heater keeps the cab warm.. It also runs TV, and a small fridge on his rolling efficiency apartment.

That truck is so tricked out that he's thinking of going to MIS (Michigan International Speedway) For an upcoming race.. Thanks to his wife (Disabled permit) he gets very nice parking.. The plan is to just stay in the tractor's sleeper (it sleeps 2) ... Kind of like driving a class B

Cummins strongly recommends shutting the engine if it is going to idle for more than 5 minutes (maybe less). If you need to idle, set the fast idle by turning on the cruise control and then pushing "set". That increases the idle to 1,000 rpm. You'll need to turn off or cancel the cruise before shifting into gear. No damage but the transmission won't move.

That Honda 2000 is the hot ticket. I used to have one, they are amazingly quiet and very fuel efficient.

Tell you what, I am constantly learning things when I read this forum. 

I too was under the impression that diesels should be idled (i.e. truckers do it so it must be right), rather than turning the engine on and off.  At some point I was told that starting/stopping diesels was more harmful than letting them idle, but apparently that is a flawed idea not based on actual fact. 

To the OP, on my gas rig it would probably make the interior hotter to run the engine... my dash A/C is pretty worthless, and a decent amount of heat comes up through the floor when the engine gets hot.  But the tactic obviously works well for your purposes and RV.

A lot of diesel lore comes from the days before electronic controls and turbos. Often, such tales have long outlived their usefulness. Problem for us neophytes is, which ones to believe?

20 years ago no self-respecting trucker would be caught dead with an automatic either. Now the drivers like 'em and the fleet managers love 'em.

When you hear engines running at a truck stop, they're more likely to be the cooling units for the reefer trailers rather than the truck engines.