If idle is to be avoided?

It depends on the engine. Modern fuel injected engines gas do not load up like they used to. Diesels should avoid idling for long times it can load up the particulate filter and it may not regenerate..
 
Idle is fine, extended idleing like in Taxi's and cop cars is a problem mostly in hot climates due to plastics being used for intakes and valve covers and much of the cooling system on modern vehicles, it being less forgiving of heat cycles. Cars doing so need upgraded oil pumps and typically an external cooler to avoid oil starvation of the cam and crank journals causing the eventual and more memorable throwing of the rods as well as a low temp thermostat.
 
Since you're asking in the HDEO forum, I'll assume you're asking about idling a diesel.

I can only offer opinions on low idle on a big rig, which is what I used to operate. Generally, we consider "low idle" to mean normal idle speed and "high idle" is a pre-set value that's usually 200 rpms or so more.

The primary purpose of high idling instead of normal idling is that it keeps the engine temps up (all fluids) when the outside temps get real low in winter, while at the same time keeping the oil pressure up which is critical.

Yes, it burns a bit more fuel but it potentially saves you from possible icing situations, particularly fuel. It also keeps the fuel rail pressure more consistent and battery charging system at peak capacity.

Do you need to do this on a small, passenger diesel? No. Just get in, start it up, drive away leisurely and let the car warm up that way. But if you're going to be idling at a rest area while napping a few hours in the bitter cold (and I mean well below sub-freezing temps), then a high idle is beneficial to have. I think several diesel-equipped pick-em-up trucks have a high idle pre-set you can use, it achieves some of the reasons listed above.
 
I never saw much issue with idling my ISB6.7 in the cold. I rarely used the high idle feature because the engine idled up when it wanted to. I did use the exhaust brake to speed warm up.

This last 24,000km index saw 100 idle hours, which was up from about 60 hours in the previous 24k index. My wife daily drove the truck all winter and it probably had 20+ minutes a day of idle. February never saw warmer than -20C, so it had plenty of cold starts.

What I found was fuel dilution was not an issue. In fact it was not reportable, which was down from 2.87% on the previous index. I cannot give much info about wear metals as I have only 2 tests on a relatively fresh engine. It does look like numbers are dropping but more tests are needed.

While some would say my idling is excessive, I think its nothing. I can idle my work truck all shift and do this often, although its a gasser.
 
I have idled my '01 Ram overnight on a few occasions when the temperature was predicted to drop below -15F. The engine burns about 5 gallons during 10 hours of idling.
Oil analysis reports have not shown serious fuel dilution problems.
 
I assume that in diesal engines a good run down the highway would evaporate the fuel from the oil.Maybe take more time than a gas engine because gas is more volatile.Is that a fast idle or regular idle?
 
It seems that the prevailing wisdom is that no-load idling on a diesel is far worse than idling with a low load. Because of ring sealing, operating at temperature, and vibrations. High no-load idle might even be worse than no-load idle as a diesel takes in and has to 'heat' twice the air, and less engine output proportionally is used to drive things like the alternator and other accessories.
 
Originally Posted by A_Harman
I have idled my '01 Ram overnight on a few occasions when the temperature was predicted to drop below -15F. The engine burns about 5 gallons during 10 hours of idling.
Oil analysis reports have not shown serious fuel dilution problems.

Fifteen and 20 years ago while working on the North Slope of Alaska, I used to idle my Alyeska Pipeline Service Company assigned PU trucks and diesels of all shapes and sizes for DAYS and DAYS on end -- when it was -30 deg to -35 deg F or colder. I've personally seen -65 deg F cold, unreal blizzards where couldn't see past your hood, and gusting to between Cat 4 and Cat 5 hurricane-force winter wind storms that few in the Lower-48 would believe.

All workers would fill up their trucks 2 to 3 times daily, and return them to the vehicle "bull rails" so we could plug them in. All of these vehicles were outfitted for "Slope" duty, which included all synthetic fluids and greases, block, battery and oil pan heaters, metal covers for brake lines and such (gravel roads), an arctic-grade grille cover, a supplemental cab heater, and specially-siped Bridgestone tires. Oil changes were scheduled for every 4 to 6 weeks, or every 2nd or 3rd two-week hitch. All trucks were installed with an LMR radio and a CB.

It was a heck of a ride the 2-1/2 years I worked up at the Prudhoe Bay and Kuparuk fields and along the northern 1/3 of the trans-Alaska pipeline system (TAPS). I have 25,000 miles on the Dalton Hwy, otherwise known as the Haul Road. Know that road infinitely better than any of those Ice Road Trucker dudes... I maintained the fiber-optic telecommunications network that carried the SCADA system controlling the pipeline back in the day.

In one or two cases, how a survived two crazy storms was either Providence or sheer dumb luck.
 
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Yeah, similar when I lived in the Fairbanks area from 82-92. But none of the diesels were the new emissions equipped diesels now. I haven't looked into it, but it would be interesting to learn how the new emissions diesels are used in those conditions.
 
Originally Posted by SteveG4
Originally Posted by A_Harman
I have idled my '01 Ram overnight on a few occasions when the temperature was predicted to drop below -15F. The engine burns about 5 gallons during 10 hours of idling.
Oil analysis reports have not shown serious fuel dilution problems.

Fifteen and 20 years ago while working on the North Slope of Alaska, I used to idle my Alyeska Pipeline Service Company assigned PU trucks and diesels of all shapes and sizes for DAYS and DAYS on end -- when it was -30 deg to -35 deg F or colder. I've personally seen -65 deg F cold, unreal blizzards where couldn't see past your hood, and gusting to between Cat 4 and Cat 5 hurricane-force winter wind storms that few in the Lower-48 would believe.

All workers would fill up their trucks 2 to 3 times daily, and return them to the vehicle "bull rails" so we could plug them in. All of these vehicles were outfitted for "Slope" duty, which included all synthetic fluids and greases, block, battery and oil pan heaters, metal covers for brake lines and such (gravel roads), an arctic-grade grille cover, a supplemental cab heater, and specially-siped Bridgestone tires. Oil changes were scheduled for every 4 to 6 weeks, or every 2nd or 3rd two-week hitch. All trucks were installed with an LMR radio and a CB.

It was a heck of a ride the 2-1/2 years I worked up at the Prudhoe Bay and Kuparuk fields and along the northern 1/3 of the trans-Alaska pipeline system (TAPS). I have 25,000 miles on the Dalton Hwy, otherwise known as the Haul Road. Know that road infinitely better than any of those Ice Road Trucker dudes... I maintained the fiber-optic telecommunications network that carried the SCADA system controlling the pipeline back in the day.

In one or two cases, how a survived two crazy storms was either Providence or sheer dumb luck.


That's some great history. Hopefully you earned BIG money in your years on the Haul Road.
 
Originally Posted by Rglossip
If idle is to be avoided what is high idle rpm range?

My Ram kicks up to ~900 RPM on its own when idling in the cold, manual high idle is 1-1.5k in increments. I usually just leave it 1k, while others I know just rely on the computer. With oil @ >190F, I just leave it be.

This might help understand the volatility of diesel fuel and if burning it off is a "thing" in an engine.
[Linked Image from researchgate.net]
 
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Idle if you want to idle. It really all just depends on the motors. A modern common rail diesel or an IDI International... you're going to have different results.
 
I idle my 2009 Chevy Express 6.6 DMAX van at least 10hrs a day, every day. Running rigs in west Texas and New Mexico I keep it running non stop while I work. Just passed 19,000hrs on the motor and 232k miles, zero issues with the engine. It's sat on location idling a week straight, powering invertors to keep the computer systems running till parts could make it to location.

This is my second duramax diesel to run had and rack up tons of idle time. Never a single issue, not even fuel dilution in the oil. (Both are fully deleted)
 
when i work cold areas i idle my cummins for weeks at a time, being an automatic, to load the engine i'd set the E-brake and put into gear. it loaded the engine and trans keeping both warm. at around 4-6 gallons over night. and roughly 8-10 a day i filled often.
no i'll effects, well over 300K on a few of them. kept oil changes around the 500 hour mark.
 
I discovered my 2017 Cummins 6.7 had over 2000 idle hrs on it in spite of the low 24000 miles when I bought it last August. I have yet to uncover an issue I can attribute to the idle hours. These new diesels are also able to regen during idle. It gobbles up fuel be side you get no passive regen to keep the DPF clean but it works.

A webasto or espar hydronic heater is well over $1000 installed so you need to be doing some serious idle time exclusively for heat purposes to make that worth it.
 
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