Leaving a diesel idle in between stops in the cold

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The temps have been around 30 the whole week in Houston and it takes about 15 minutes for my truck to warm up and that's driving it. So then if you [censored] it off for 25 minutes or so it practically cools back down. Then there goes the heater. How many of you just let it idle in between trips when you run in somewhere and it's only going to be 20 minutes or so.
 
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In the past week, we have gotten fifty degrees colder than you, and I still don't do that! I mean it's your truck, and your diesel. Three or five minutes? Sure. But twenty? I'd shut it off. But here, even in the extreme cold, I don't idle for more than a couple of minutes. Why? Fuel dilution, the fact that idling isn't great for the engine, and the fact that the fuel isn't free. That said- stopping in for coffee and a donut? I let it run, if it's truly cold (below zero or so). But grocery shopping or something like that? I shut it off. Of course, do what you're comfortable with! Just a northerner's perspective.
 
New thermostat? You just described exactly what my Cummins was doing, until I changed the thermostat.
 
Originally Posted By: TmanP
Why? Fuel dilution, the fact that idling isn't great for the engine, and the fact that the fuel isn't free.
Maybe not all diesels get fuel diluted. In North Dakota in the winter, I'd let the International TD-9 idle for days - or it would be EXTREMELY hard to start again.
 
I suggest turning it off. Diesels warm up when under a load. Idling is a waste of diesel and shortens the life of diesels. I've run well over a thousand in a fleet, mostly Ford 7.3, and 6.0.
 
Block off 3/4 of the radiator with some card board. It isn't gonna stay this cold forever. That way the truck will get warm faster, and cool off slower when parked.
 
My '82 Benz starts warming up fairly quickly. If more of my daily driving regimen was trips long enough to get it truly warm I'd be more keen on shutting it off when it'll sit for more than a minute or so, but unless it's already fully warm I'll leave it run for up to 10 mins. in some cases. The OM617 is a tough powerplant - I figure a few more minutes on the oil and keeping the oil up in it is better than keeping it below operating temp. + putting it through that many starts and temperature cycles. It seems to burn very little fuel at idle, too, so that takes a little of that nagging idea that I'm burning away $$$ for no good reason.
 
some states have "NO IDLE laws and zones for big trucks , I dont know if they apply to light or medium duty diesel trucks if your going to idle for an extended period of time , bump the the throttle up to about 700 -800 rpms that way you will be having consistant oil pressure to lube up the turbo and you will find it easier to keep your emmissions profiles in line ,, my old 2012 KW T680 with a PACAR motor always had emmissions issues when idling at 600 rpm in the cold or summer , at 800 RPM , NO PROBLEM, and at 700-800 RPM you circulate more warm return fuel from the pump to keep your fuel warm and it prevents cross overs between tanks from freezing or gelling in-20 weather
 
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In the extreme cold, if its only a few minutes I will idle it. If it is more than that I just shut it off. My new diesel starts like a dream in the cold. The seasonal blended fuel has not give me a lick of trouble either so I am not worried about it gelling. Only once, not long after we bought it did we leave it idle for an extended period. I think the ambient was -35C or so and a heavy wind chill. Winter front closed up, idle up to 100orpm and the exhaust brake on. Thing was toasty!
 
A deisel isn't like a gas engine, I d let it run. Deisels are made to start up and keep running. Not for start and go stuff. Let it run, the fuel use is so small. Up North everybody in the winter time let their deisel trucks idle while they were in church. It's better for them.
 
I'd definitely make sure that I'm not turning off in the middle of a regen if you're going to be turning it off. Doing that would be much worse than just letting it high idle.
 
Originally Posted By: Linctex
New thermostat? You just described exactly what my Cummins was doing, until I changed the thermostat.
The thermostats used in Cummins engines tend to fail toward getting lazy. Failure toward closed or opening late is significantly less likely. My old thermostat wouldn't let the engine get past 150° in Florida summer with AC on.
 
In some northern climates (like Siberia) they leave diesel truck motors running 24/7 whether in use or waiting overnight for the next shift to start.
 
Originally Posted By: DoubleWasp
Originally Posted By: Linctex
New thermostat? You just described exactly what my Cummins was doing, until I changed the thermostat.
The thermostats used in Cummins engines tend to fail toward getting lazy. Failure toward closed or opening late is significantly less likely. My old thermostat wouldn't let the engine get past 150° in Florida summer with AC on.
Yeah it might be getting lazy. It's been a while since we've had cold weather. Last year it never even got cold.
 
Its about time to change the coolant again. I change it every 5 years and put a new t-stat in at the same time.
 
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