High vs low idle question

I'm posting this here to seek general information, if it's in the wrong place feel free to move it.


I'll just get straight to the point with my question, I have heard numerous times over the years that it's best practice to high idle an engine to prevent excessive wear. The carrier that I drive for has high idle disabled, pushing cruse control while parked does nothing. if there are so many downsides to low idling an engine then why would a carrier disable High idle?

 

Higher RPM equals more wear. There is no evidence that increasing base idle does anything to prolong regenerations intervals or decrease particulate/soot buildup from EGR while idle.

A modern Diesel engine needs increased load to generate more heat to be efficient in operation. Increasing base idle does not accomplish this.

Why would a carrier disable high idle?

Fuel savings…however small.

 

A company might disable high idle because they want you to NOT IDLE. Ask your company, we can't read their mind.

 

Oh yeah of course my company has a idle policy. The truck has an APU but its been broke since i picked the truck up 4 months ago, since the company is exceptionally slow about fixing idle reduction equipment.. and yes they are aware of the broken APU. as far as the truck is concerned it will let me low idle as long as I want to. High idle not so much.. I don't really care if I low or high idle personally I just wondered out curiosity.

 

Some trucks have buttons you can push to increase idle speed to up to 1100 or 1300 RPM range. Some people might consider that high idle. High idle in years past was wide open. Two different definitions for the same thing.
Years ago with mechanical fuel pumps folks often used a hand throttle to set the idle speed at around 900 - 1100 RPM. That way they made enough heat to sleep in, did not droll oil out the exhaust. Low idle was supposed to be bad on those old turbos.

Reread your post: It is the companies truck, why go against the flow? Some of those can work with the truck parking brake released and a stick on the throttle. Do not be dump and roll away.

 

Like I said I don't really care if the company prefers low idle; I am mainly asking out of my own curiosity perhaps I could gleam some knowledge for if I actually did decide to run my own truck... perhaps I worded my question poorly and made it sound like I had a problem with low idling a company truck, I apologize for the confusion

 

Goodysnap is a much better guy for that info than me. I have a pretty new smaller diesel truck with 111,000 miles. It has all that emission crap. If it does not need a cool down or I am not driving it I turn it off. Figure starters are cheaper than all that emission stuff.

 

It probably is, I can't tell you how many emissions related breakdowns I've had over the years. It is possible that the advice is simply antiquated. As I do remember that caterpillar recommended High idling their engines, but that was also before DPF and all that started taking effect.

 

High idle will keep oil pressure higher. And in cold temperatures it's best to high idle to keep coolant temp up in order to prevent wet stacking.

 

I dont idle my truck much. Usually only on a cooldown after a hard run in high heat or to run my microwave. Usually long idles are in say a long line at a plant that moves every 2 or 3 minutes but still takes 2 hours.

That said i do bump the idle up a bit as at low idle for extended periods especially in winter the oil can cool enough that the engine begins to lug just a little and the oil pressure will go way up. Same reason i give it a 10 min warmup before i roll. Oil will spike as high as 85 or 90 when dead cold if i try to pull out in winter without a warmup.

Im sure theres more technical reasons to do it. But my engine has 913k miles and 21k hours without a rebild and the samples all come back golden so ill keep doing it that way unless i find a reason to not.