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

That's been my experience too Ned.  I think once upon a time the truck engine had to be running to keep the load cool, but not any more.  Very true Gary, a lot of "fact" about diesels came from some really old time truckers.  Not bad info, just a little dated. With all the electronic gadgetry incorporated into modern diesels, they bare scant resemblance to the latest marvels.  And with the addition of urea injection systems things are going to get even stranger.  I guess they call it "progress".........

We have also went from 2 stroke to 4 stroke diesels.

One other reason not to let engines slow idle for long periods is that some components like the valve train are still splash lubricated and need the extra RPMs to keep the oil moving around.  I can remember when Detroit Diesel changed their break in recommendations to a very short idle time and then get the RPMs up for that very reason.

An idling engine is just flat out annoying if you are parked closer than 100 yards.

I suppose under certain conditions, it could be annoying.  Like living in a National Park far from other noise, mild weather with people outside or with their windows open, etc.  But in the middle of a big city, with the constant roar of traffic from the boulevard, airplanes, the wind, etc. at a time when the temperature is well over 100 and there is not a soul outside and everyone is inside their own insulated motor homes with the windows closed tight and the A/C on high and the TV or the stereo on loud enough to hear over the A/C . . .  And if after carefully checking, I still got it wrong, I'm pretty sure the serious looking security guys driving past close by in golf carts would have something to say.

As I said twice in this thread, if there was the hint of a possibility of annoying a neighbor, I wouldn't do it. 

Okay, I'm going to show my ignorance. We were told to idle the diesel for at least five minutes after driving, so cool down hot parts (turbo?). Is that not right? Then, is it critical to shut down in five minutes, or what happens if it is ten or fifteen? Just asking.

Usually the time from exiting an interstate to get to the campground or other stop at low speed is sufficient time for the turbo to cool down.  A few minutes extra idling, if in doubt, won't hurt the engine.  We were talking about extended idling.

I figure by the time I get into a campground, everything is at reasonable temperatures. Now if I roared into an interstate rest area after a bout of 65 mph travel, I'd give it a couple minutes at idle. Not five, just a couple.

The real difference in today's diesels vs. yesterday's idlers is all the EPA junk on the engine. Idling diesels with such things as EGRs and DPFs can get costly.

I agree. And the fact that old time diesel used to be much closer to pure oil than it is now. Lots of additives in there now.

roamingrob said:

I suppose under certain conditions, it could be annoying.  Like living in a National Park far from other noise, mild weather with people outside or with their windows open, etc.  But in the middle of a big city, with the constant roar of traffic from the boulevard, airplanes, the wind, etc. at a time when the temperature is well over 100 and there is not a soul outside and everyone is inside their own insulated motor homes with the windows closed tight and the A/C on high and the TV or the stereo on loud enough to hear over the A/C . . .  And if after carefully checking, I still got it wrong, I'm pretty sure the serious looking security guys driving past close by in golf carts would have something to say.

As I said twice in this thread, if there was the hint of a possibility of annoying a neighbor, I wouldn't do it.

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I have been annoyed by engines running in a city hundreds of times.

Sounds like you spend WAY too much time being annoyed!

I'll bet that none of you will own a motorhome engine long enough to know for sure what will wear it out, idling or not. Here's two examples that the "common wisdom" is advising against. #1, leaving the engine to idle for extended periods. What do railroad locomotives do? They either have an automatic start/stop to keep air pressure and heat up, or they leave them to idle. The local communter train is left at idle every weekend from the last trip on friday until the first trip on monday morning. They do this because it costs too much to shut it down. The train runs or idles continuously and they do not expect unusual wear.

Second, I'm familiar with an entire fleet of vehicles, mostly high HP Detroit 60's that are started and run flat out with no warm up idle time. By that I mean the engine is started, put in gear, brake released and driven hard, for anywhere from 1 minute up to 15 minutes and then left to idle, sometimes for up to 12 hours at a time. The fleet uses no block heaters but does store the vehicles inside year around between uses. Vehicles are used this way 24 hours a day 7 days each week for up to 20 years. Some of the fleets vehicles are parked in the middle of hills and literally pull out of the building, turn right for 100 feet, then a left turn for full throttle use up the hill. That tends to warm them up pretty quickly. Again, this particular fleet has about 20 vehicles with a GVW of about 37,000 pounds, another 6 with a 54,000 pound body/chassis.

Current experience is one unit retired with over 200,000 miles and no engine repairs. No injectors replaced, no valve jobs, no ring jobs, no bearing problems etc.  Some units have required injector service after 120,000 miles or so. Those are the exception. You probably have seen these Fire Department fleets and know that they generally drive them pretty hard to protect life and property.

So, looking at those examples, I drive my motorhome with a little more care. I seldom idle longer than 3-5 minutes before moving. I seldom idle longer than 3-5 minutes while parking/parked. I let my engine use it's full power range while going up hills as it's cooling system is capable of that use without overheating. I'm sure my engine will outlast me with proper oil changes, coolant service, and routine maintenance. I believe that if you ride/drive in a Spartan chassis with less than optimal care you will get a pretty good feel for what hurts or doesn't hurt an engine and chassis.

bucks2 said:

You probably have seen these Fire Department fleets and know that they generally drive them pretty hard to protect life and property.

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A good friend of mine wrote the only book on fire engine apparatus maintenance and repair.  Said book is recommended reading by the USA dept of homeland security when they supply fire engines.  He writes articles on fire engines and is a heavy duty mechanic.  I always ask him questions like this but haven't heard him on the air in the last few days.  (He's also a radio amateur.)

In addition to all the good advice given already. Extended idling can burn out an automatic transmission in short order on some vehicles. My Dodge Cummins (2001) does not spin the tranny front pump in Park or Neutral. Thats just the way they were built.Running the diesel without the pump turning heats up the torque converter, already the weak link in the Dodge tranny. Check your specific engine trans setup to see if this also applies to your rig. Thats one reason you seldom see a Dodge/Cummins emergency vehicle.

Sarge. I think you got it right!! My uncle left his cummins running all night long and had 1,250,000 miles with two in-frame majors but it also was a 68 KW and the last time I rode was in 1974. alot of changes since then.

I thought Las Vegas didn't get humid, so the hot air was dry and not humid. At least it was like there the times I was there, but that was back in the dark ages.  :

It seems to me, if you used a fan in addition to your regular A/C you would "feel" cooler.

I'm in 90+ degree weather in Ohio at the moment, and I've only run my A/C once in 10 days, but I always have a fan or two going.  And, to be fair, I picked a spot with a big shade tree.  I also have big windows I open, I love to have views, can't stand to have my shades all closed up in the daytime unless it's siesta time and I absolutely need them.  Of course I'm a southerner, so I drink buckets of iced tea all day...

Frankly I don't like the newer RV parks that have no tress, so I look for the older parks that often have nice landscaping and lots of trees.

My A/C has a wonderful fan I use often without the A/C on and I recently bought a powerful 12 volt fan at a truck stop with a big long 12volt cord.  Some nights I aim it right at my bed, as being a sailor from the Caribbean, I was used to sleeping under an open hatch that pushed the wind in the face all night.

I wish the RV industry would make a pop-up canvas tent like structure to pop up over the RV roof about 2-3 feet high, leaving a dead air space, between roof and tent, that would go miles towards helping to cool an RV.  I saw this in a Caribbean campground, they had put big tarps up higher, over the tents and little cottages, what a huge difference it made.

Recently in a state park, (lots of trees)  a guy pulled in, and tossed ropes over the high tree branches, then lifted up a big tarp to partially cover his RV roof and RV  awning.  It looked a tad goofy, but he said it reduced his temp by  10 degrees.

I too am familiar with modern diesels and work in an arctic enviroment, we have dozens of trucks and cat front end loaders working all day/night every day, idling is not hard on them as long as you kick up the engine speed to 1000rpm or greater in extreme cold, 1500rpm is common in very cold weather, but ine summer,1000 will do. The Cat engines have 50,000 hrs on them with little problem! One reason to let the diesel idle for five minutes before shutdown is also to let the turbo unspool to a slower rpm, when you shut the engine down, oil stops flowing to the turbo's bearings, and a high spinning turbo with no oil pressure is bad. We have to let the engines idle for days and days at times, and we really don't see any problems as long as the idle is increased.