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Old 01-15-2013, 09:54 AM
 
2,341 posts, read 7,797,741 times
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Quote:
Originally Posted by kanhawk View Post
My dad always told me not to let an engine idle more than a couple of minutes when I was growing up in the 60s and 70s, that it would damage the engine. Was that true then and is it still true for late model cars to let an engine idle beyond a few minutes?
It was more true then than now. Even so, there is really no benefit in sitting and letting an engine idle.

The antidote to excessive idling is to take the car out and drive it at highway speed long enough to get all the condensation out of the engine and exhaust system.
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Old 01-15-2013, 10:06 AM
 
Location: Pittsburgh area
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Quote:
Originally Posted by Coldjensens View Post
I can confirm that idling wastes less gas than constant re-starting
This is going to vary based on a lot of factors. In the pizza example, the idling is probably minimal so that could make sense. If you're idling for 10 minutes, not so likely.
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Old 01-15-2013, 12:01 PM
 
Location: Northern MN
3,869 posts, read 11,527,587 times
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In the summer your engine may be able to maintain operating temp but a diesel or gas will not be able to in the winter.
Most modern vehicles have been controlled by a ECM for a long time now.
Mine idle up on their own as temps fall.


Idle a diesel or any engine can "idel" at rpm over the lowest rpm the engine will run at.
If I set it to run at 2krpm it is idling at 2krpm.

As stated some quote earlier oil changes, why...
Because of cylinder wash. Changing the oil is a step to stop the damage from oil dilution.

Yes I too have idled vehicles for extended times but is is not "good" for them. extended times 4-10hrs+

Prime vehicles for this kind of damage is police cars. Police cars spend an inordinate amount of time idling writing tickets, filling out reports and stake outs. I have replaced many a connecting rod bearing in police car engines because of this

The other effect is not so drastic. It is an idling engine may not get hot enough to start the catalytic convert working or hot enough to run efficiently. It may also load up the catalytic converter with fuel that could lead to an early demise of the catalytic converter.
this.
http://autorepair.about.com/library/a/1h/bl151h.htm

Do you have to worry about this? Unless all you do is run your engine at idle, yes. But if you sit in the line at the McDonalds drive through for 10 or 15 minutes, no. You don't have to worry about it.


This is an opinion from Cummins....


We publish and state some simple guidelines, but we have no official policy for diesel engine idling. Basically, engines are made to work and not idle. Excessive idle shortens oil drain intervals, is classified as "severe duty" service, and - under the worst of conditions - can lead to engine damage.

One issue with excessive idling is injector carboning which can lead to premature failure or increased injector maintenance. Excessive idling can also cause carbon build up on pistons and piston rings, which can lead to excess oil consumption.

Anything more than 30-40% idle is considered severe duty service, but how that percent idle is attained may be worse than severe. We generally don't like to see engines idled for more than 10 minutes. If the idle speed is increased to 1,100 -1,200 rpm then internal engine temperatures are warm enough to prevent the worst case damage and also pollute the air less.

Low oil sump temperatures, combined with low ambient air temps and low speed idle cause incomplete combustion, producing sludge, carbon deposits on injectors and internal engine components, weak organic acids in the oil - and, ultimately lead to valve sticking and bent pushtubes/pushrods.

There are options. Idling up the RPM as stated above is one. "Smart" systems which turn the engine off/on (while maintaining adequate coolant temperature) are another. Cummins has a system called ICON which does just that. Sometimes though, the engine needs to run - not just for the comfort, but for the safety of the operator. Arctic operations are an example.

Generally, people have held the traditional belief that diesels should just "hammer away" at idle, and this is sort of a "diesel thing." This is an old belief that needs to be dispelled. Operators and drivers prefer to keep the engine running for warmth in the winter and for A/C in the summer. Actual idle times are higher than one would expect, except for disciplined fleets which either reward for low idle times or provide other incentives.

In past studies, Cummins has determined that low speed idle can contaminate the oil at between 1-1/2 to over twice the normal rate; this is one of the main reasons for recommending "severe duty" maintenance intervals for engines operating with more than 40% idle time. Another reason is that, if sump temperatures are not sufficiently high, the water (produced by combustion, let alone condensation) will not be heated enough to evaporate from the oil.

In the Dodge/Ram Cummins midrange engine application, both Dodge and Cummins have recommended owners to limit idle time to 5 minutes and have also offered a software upgrade "idle up" feature, which increases the idle speed, warming up the engine enough to limit incomplete combustion byproducts.

There may be some balance in stop-and-go driving and urban delivery, wherein one would trade off the benefits to be gained from reducing idle time against the fact that shutting the engine down (every time it's not pulling a load) necessarily creates a "starting event." If the "off time" is long enough, there is a transient starting event time where the oil pressure is not fully established and the engine is running. Accelerated wear can occur during these conditions. In hot temperatures, when the oil is thinner, the oil drains away quickly so some degree of idle may be preferred to starting/stopping and restating the engine fifty times a day.

Common sense may be the best guideline. Common sense would include an appreciation of the above and factor in outside temperature, whether or not the engine will be run for a long enough time later in the day (to burn off carbon and water), how long the idle is, whether or not the A/C needs to be run, etc. Again, one of the parameters defining "severe duty" is excessive idle time; running at idle for more than ten (10) minutes probably doesn't make sense; the "smart idle" ICON-type devices will help; balancing the cost of excessive idle vs. the utility/necessity/option of idle, etc.... all of these considerations should be factored in."


from ford.

why change the oil early, fuel contamination.

What exactly is extended idling?
Ford Motor Company defines extended idling as follows:
Over 10 minutes per hour of normal driving
Frequent low speed operation
Sustained heavy traffic less then 25 MPH
One hour of idle time, is equal to approximately
25 miles of driving

If any 6.0L powered vehicle falls into the above
categories it is classified under Severe Service
Operations and thus the following maintenance
intervals are suggested in the Owner’s Manual:
Oil Filter: 5,000 miles, 200 engine hours, 250
gallons of fuel or 3 months (whichever comes first)
Fuel Filters: 10,000 miles, 400 engine hours or
6 months (whichever comes first)
DSLIDLETIMESS 12-08
Motorcraft and Power Stroke Diesel are registered trademarks of Ford Motor Company
2008 Ford Motor Company
Example: Each day a certain vehicle averages 50
miles driven and 6 hours of idle time. Here’s how its
maintenance schedule would look different based
simply on miles driven:
5,000 miles recommended interval divided
by 50 miles driven per day would result in a
scheduled oil change every 100 days
Factoring in the idle hours on those 100 days:
6 hours of idle time per day at an estimated 25
miles per idle hour (from above; one hour of
idle time is equal to approximately 25 miles of
driving) results in 15,000 simulated miles.
Conclusion: after 100 days the engine oil actually
has 20,000 miles of wear!
If this vehicle were to
perform scheduled maintenance based on engine
hours instead of miles driven the interval would
change to approximately 30 days.


https://www.fleet.ford.com/truckbbas...IDLETIMESS.pdf


HAHAHA funny McKinny.
I'm the only one who can back up what they post.

Last edited by snofarmer; 01-15-2013 at 12:11 PM..
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Old 01-15-2013, 02:42 PM
 
Location: Texas
4,733 posts, read 10,116,476 times
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Considering this thread has taken a different course and it's over diesels, here's Fords view on idling and the whys for their engines.
http://www.powerstrokediesel.com/doc..._Intervals.pdf

Not all diesel engines are fired by oil compressed injectors. Most are pintel type which makes a difference in how the oil is sheared. Usually, in most modern diesel engines of the type found in large rigs, carbon deposits are not an issue with idling an engine. Yes, the coolant temp falls when idling in the cold winter but it hardly falls at or below the ambient temperature where an engine would have to start. The engine oil would also not be ambient temperature causing more damage at cold startup. That's why you usually see diesel rigs idling over night. Trains use an oil that is more akin to sludge, its' extremely heavy. So heavy it's not going to pump thru a typical road diesel or gas engine. It has to stay warm or you won't start the engine. They also use heaters to keep it up to an operational temp in the winter. Oil rigs use the same type lubricant as well diesels found in large ships. Just because it uses diesel fuel doesn't mean that the engines are close to being alike. About the only thing some of them share is the fuel and high compression as compared to a gas engine. Like any vehicle you buy, read, understand, and follow the owners manual. Pretty simple, huh.
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Old 01-15-2013, 03:24 PM
 
Location: Not far from Fairbanks, AK
15,695 posts, read 25,308,395 times
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Maybe truck drivers all over the US leave their trucks idling at the truck stops, and rest areas (winter and summer), because extended idling is bad for the motor? It's +80 or maybe -40 degrees outside and some of them want to sleep at few hours, but they turn the motor off because it will extend its life?

Taxi drivers turn their motors off at train stations, airports, and so on? How about train locomotives?
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Old 01-16-2013, 09:17 AM
 
Location: Meeami
530 posts, read 1,877,088 times
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Quote:
Originally Posted by RayinAK View Post
Maybe truck drivers all over the US leave their trucks idling at the truck stops, and rest areas (winter and summer), because extended idling is bad for the motor? It's +80 or maybe -40 degrees outside and some of them want to sleep at few hours, but they turn the motor off because it will extend its life? Taxi drivers turn their motors off at train stations, airports, and so on? How about train locomotives?

This tells you the truth right here.... And if it caused real damage that equaled failures and cost them money, no they wouldn't do it.. they would turn them off. Money and time without the vehicle is what those guys are about, not internet drivel, not manufacturers recommendations, not common sense or 'what your brother said'. Just the facts. Police cars too are left on many hours a day, and not only do they do well in that line of service, people go to auctions and fight for them after the fact.
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Old 01-16-2013, 09:36 AM
 
Location: Frederick, MD
1,807 posts, read 2,158,968 times
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Bottom line is don't do it unless it is really needed. Taxi drivers don't really need to do it sometimes. Temperatures here in nights are like 32F and even then in the morning I see people turn ON the cars and leave them there for 1/2h.
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Old 01-16-2013, 10:53 AM
 
Location: Northern MN
3,869 posts, read 11,527,587 times
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Only by kids with ego problems or the misinformed who think they are buying the fastest car around by a worn out cruiser.
them are the facts.

police cars see damage from excessive idling like overheating and worn main bearings from low oil psi and from oil dilution.

Quote:
Police cars too are left on many hours a day, and not only do they do well in that line of service, people go to auctions and fight for them after the fact.
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Old 01-16-2013, 10:59 AM
 
Location: California
10,091 posts, read 34,110,172 times
Reputation: 22017
Quote:
Originally Posted by Felix C View Post
Strangely enough the 2013 BMW in our family turns off when the engine is at idle for a few minutes. Entirely normal according to the dealer and sales literature. Re-starts immediately upon depressing the accelerator.

It is called Start Stop

here is a link: Don't Like Your BMW 3-Series' Start Stop? Have It Reprogrammed
You'd have to have it set to turn off...we also have a 2013 M3... It is the only feature on the car We dislike and have it set as to NOT turn off when sitting at a light or just idling for more than a few minutes.

And it does't have to be reprogrammed, at least not on the M3...just toggle the switch.
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Old 01-16-2013, 01:41 PM
 
Location: California
10,091 posts, read 34,110,172 times
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Quote:
Originally Posted by ShelbyGirl1 View Post
You'd have to have it set to turn off...we also have a 2013 M3... It is the only feature on the car We dislike and have it set as to NOT turn off when sitting at a light or just idling for more than a few minutes.

And it doesn't have to be reprogrammed, at least not on the M3...just toggle the switch.
In thinking about this....the default is OFF on the Start/Stop for the M3.
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