We both worked for a large metropolitan transit agency. A few years back, the head of the maintenance division put out a bulletin stating that all engines should be shut off immediately when arriving at a terminal. And, that engines should be started no more than a minute before taking off from a terminal or just enough time to build up the air. The edict stemmed not only from the public complaining about the pollution issues (some might contend a non-issue with the modern particulate traps) but also because of the noise a diesel engine makes while it idles unnecessarily at a terminal which may be located in residential areas bothering residents.
Years ago when I first started driving buses, we used to let them idle for turbo cool-down at the terminals and start them up early before leaving terminals on cold or below freezing days. When we questioned the mechanical department on this edict, they told us that the modern diesel engines no longer need the cool-down as they once did and there's absolutely no need to "warm them up" in the winter. They insist that there is no excessive wear issues when NOT letting them idle.
These are essentially the same Cummins and Cat engines that are in motorhome applications. I cringed at shutting them down without letting them idle for a few minutes before shutting them down or starting them up to let them "warm up" a bit before leaving but management threatened to "write us up" if we disregarded the edict.
In our own motorhome, I won't shut it down as fast as I did the transit bus but will not let it idle for more than a minute before shutting it off. We don't "warm it up" by idling it but as others have said, as soon as the air is up, start to drive easily until oil and water are at normal operating level temps.
I have heard that long idles create carbon buildup in the engine. If I have to idle for a while I hit the high idle button which is suppose to stop the carbon build up. My coach has a two minute countdown to be able to raise the tag. After checking into a campground if I have to make a tight turn, I have to sit two minutes before proceeding. Some might think I'm just wasting time.
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The best thing for ANY internal combustion engine (gas or diesel) is frequent USE. That is running everything up to normal operating temperature for a "period of time" - how long, enough to get rid of the water. When an engine cools, it draws ambient air into the crank case and, with it, any moisture content (higher humidity = more water). Moisture combines with oil over time to convert some of its components to acids. The combination of moisture, air (i.e. oxygen) and acid on metal = corrosion. Idling for 30 +/- minutes is not enough "normal running" to bring the temps up to where the moisture in the oil can "steam distil" or boil off to the outside. Take it out for a drive for the half hour instead of just letting it idle. All the running parts will be exercized and be kept healthy.
fordsooperdooty wrote: Big over the road rigs no longer practice idling when parked for a number of reasons. All light duty diesel manufacturers now recommend no more than a 3 minute idle prior to parking, with a maximum of 5 minutes on large displacement diesels during hot weather or after an especially hard pull.
30 States have adapted a "diesel engine idle reduction standard" (also called "idle-free") from the Feds, and State and Federal grant money are available to fleets. Trucks in the USA use an average of 840 million gallons of diesel per year just idling! Most fleets have gone to 'auxiliary power units' (small diesel generators or electrical outlets next to the parked rigs) to power over the road trucks cab heat, engine heaters and air conditioning when parked.
Not Only does it save money on diesel, but prevents additional wear that occurs when a diesel idles for extended periods. A idling engine may experience a situation called "cylinder wash-down" where diesel will actually wash the lubrication off of the cylinders accelerating piston wear.
Somebody better tell the owner-operators, along with everybody else. Many are still doing it. Most fleets in the northeast do not have the Onan power units or other brands either. Maybe in California, but not here!
And you can prevent the additional wear by idleing up to between 1200 and 1500 rpms. Then you are getting lub. And there are ways to keep the rig from shutting down on its own.
I know zip about diesels but have noticed that UPS drivers shut down immediately when they make a delivery, even if I'm standing there to get the package. Our guy says they are required to do this. That's a lot of starts and shut downs in one day.
I hope the DP owners that I often get parked next to read this thread. 30 min idles on arrival and departure are not rare.
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I think far too many missed "the point" and just interjected their own wants and wishes instead.
The "question" was about WEAR...not about wasting fuel or making the "tent camper" next to you angry at your "excessive" idling...etc...etc.
Certainly any time your engine RUNS...and you arent moving at all..is a fuel "waster"...and "excessive" to some isnt very long to another...time is all in the "eye of the beholder".
Personally...and this is ME and ME alone...I WONT idle my rig for 2-3 minutes...whether I just started it up or have been driving for say 8 hours....and also on the other hand..as long as I own it , it will never see a 30 minute idle duration
But to the original "question" it appears that at "high idle" actual WEAR doesnt amount to "doodlie squat" per hour
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I think it only seems like a 30-minute idle session to many neighbors. I know it does to myself when I am leveling and then putting the slide out.
Some times the computer zips through the air leveling process, other times it takes its own time. Only when level do I put the slide out and by that time it could be that the neighbors' wrist watches have lept into overdrive.
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jimnbubba wrote: When I was a trucker ,we would idle our trucks,hard to sleep at 30 below zero and 115 above zero,however we would bump up our idle speed using the criuse control to about 1000-1100 rpm
Low idle will not produce enough oil pressure for the turbocharger bearings and that is why you need to go to high idle. All the engine manufactuers track the amount of idle when they print out the engine operations from the engine computer. I have parked my motorhome for 3 months at a time in a campground and never start it until I leave unless I can take it out onto the highway and drive it at highway speeds until all the temperature gauges are at the normal operating range.
John&Joey wrote: So were the boat engines taking water from outside, or was it a closed system like a MH? Saltwater or fresh?
Don't know what this has to do with RVing, but:
Most modern marine engines have "closed cooling systems". The engine has regular coolant in it. This coolant circulates through a HEAT EXCHANGER that functions as a radiator does on land vehicles. It is a water to water "radiator" vs water to air radiator.
The marine engine has not only the regular water pump, but a "raw water pump" that brings in sea water and puts it through the heat exchanger.
On some metal hull boats part of the hull is used as the heat exchanger-- it is called a "keel cooler". The heat from the engine coolant circulated in contact with the metal skin of the vessel removes the heat from the coolant.
It doesn't (that was the whole point.) I have been around boats for 30+ years also. I also know about the different ways to exchange heat on them.
Remember, when you're talking about marine application you can be talking about a huge HP engine in a car ferry with a closed system, or an open system Atomic sailboat engine.
My whole starting point (which only slices have been pulled out to help justify the persons position) is that I've been hearing this excessive idle, or not, nonsense for 40+ years. Let see, carbon buildup, acid in the oil etching the main rod bearings, cylinder walls being washed of lubricant, power loading too soon which will create a cold piston seizure, seals drying out, will create condensation (I've also have seen engines covered in condensation stored inside on cement, wonder how the inside looked)etc.... Yet in all those years I have yet to ever hear anyone with first hand (got to tear the engine apart) experience with any of the issues because they idled too long or not long enough.
My bottom line (as I stated in the begin) is IMHO that it doesn't matter. It matters much more that you use the MH and not let it sit.
jimnbubba wrote: When I was a trucker ,we would idle our trucks,hard to sleep at 30 below zero and 115 above zero,however we would bump up our idle speed using the criuse control to about 1000-1100 rpm
Low idle will not produce enough oil pressure for the turbocharger bearings and that is why you need to go to high idle. ...
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