At what temperature do you leave the truck running?

Discussion in 'Questions From New Drivers' started by Canadianhauler21, Jan 22, 2025.

  1. Canadianhauler21

    Canadianhauler21 Heavy Load Member

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    It's been pretty cold out here lately, about -22F. I was told when i was new that it's best to leave your truck on when it's super cold. Over 15F I just use the bunk heater.

    Is their any benefit to leaving the engine running or is it just a myth?
     
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  3. 77fib77

    77fib77 Road Train Member

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    I keep it running like 1/2 the night below 10'F. I dont really know. I'm my mind. Batteries get colder they lose power. So really cold weather means batteries have 50% of their power? That plus a cold engine means it might not start back up. Then your screwed. But in the mid west that doesn't happen often. I also have a generator in the headache rack and a good battery charger on the truck.

    6 weeks will be March.

    temp-800x545-1.jpg
     
  4. 201

    201 Road Train Member

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    Anything below freezing, but that was an old BC Cummins. Contrary to popular boss lore, idling doesn't hurt the motor. It is important to set the idle up, say 1,000 rpms. Newer motors can start down to 0 I think, but starting a stone cold motor is much worse than a couple hours of idling. With service calls in the hundreds of dollars, seems pretty foolish not to keep it running. A bigger issue would be air brakes in the real cold. Make sure that air dryer is up to snuff.
     
  5. motocross25

    motocross25 Road Train Member

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    I was always told that as well that a cold start is much rougher on an engine than an all night idle.
     
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  6. Frank Speak

    Frank Speak Road Train Member

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    Right, the only thing it hurts is the bean counters butt.
     
    Last edited: Jan 23, 2025
  7. idriveaholden

    idriveaholden Super Heavy Hauler

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    -15 or less Fahrenheit

    Depends how well you truck handles fuel gelling also
     
  8. RustyBolt

    RustyBolt Road Train Member

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  9. OLDSKOOLERnWV

    OLDSKOOLERnWV Captain Redbeard

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    If I’m uncomfortable I fire the engine up. But I don’t have a modern electronic engine like most of you, so I don’t shut it down when it’s below 20 degrees with no way to plug the block heater in.

    I’m the driver, the mechanic, the owner, and the bean counter, I just do my own thing.

    I still run a Big Cam Cummins, I idle it up to about 1200 when it’s real cold, if not it will start wet stacking eventually with this N14 air to air setup…..
     
    Bean Jr., D.Tibbitt, 77fib77 and 2 others Thank this.
  10. AModelCat

    AModelCat Road Train Member

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    Idling is rough on the engine. Can't make enough heat so you eventually start slobbering unburnt fuel into the exhaust. I would never consider leaving a truck running at under 1200 RPM regardless of the ambient temperature.
     
  11. okiedokie

    okiedokie Road Train Member

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    In Artic temps don't set your trailer brakes just the power unit.
     
    201, lual, 77fib77 and 3 others Thank this.
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