2000 Freightliner 12.7 operating temp. Running too cold.

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Rideandrepair, Feb 10, 2021.

  1. Rideandrepair

    Rideandrepair Road Train Member

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    852027CA-3BE0-4787-B4A3-44C45C38FA1B.jpeg Trucks running too cold. Besides thermostats, could anything else be the cause? 2000 Freightliner Classic. 12.7. Here’s a pic idling. 21 degrees out. Gets a little bit colder going down the road. Even at 50 degrees outside temp. New 190 thermostats, New radiator, fans not running. Kicks on normally, though a bit early, just below 200 in summertime. I think sensors good, and gauge is accurate, judging by the heat in cab. I must have a thermostat stuck open. Any ideas of other causes?
     
    Last edited: Feb 10, 2021
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  3. Trucking in Tennessee

    Trucking in Tennessee Road Train Member

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    When you put the thermostats in did you get all the air out of the system?
     
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  4. DUNE-T

    DUNE-T Road Train Member

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    My truck runs at the same temp that you have in the pic. Why do you think something is wrong?
     
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  5. swaan

    swaan Road Train Member

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    If thermostat are good then put a winter front on the grill
     
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  6. Rideandrepair

    Rideandrepair Road Train Member

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    Yes, they’ve been in for a while.
     
  7. Rideandrepair

    Rideandrepair Road Train Member

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    Thermostats are 190. I had 180s, but radiator was old. My Detroit’s have always ran below 180 or 190. But never this low.
     
  8. Rideandrepair

    Rideandrepair Road Train Member

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    Haven’t checked or changed thermostats yet. Maybe just the 4 row radiator, doing too good of a job? Seems with 190 thermostats it should get warmer, especially idling. Even at freezing temps.
     
  9. DUNE-T

    DUNE-T Road Train Member

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    Mine also were at 180, I decided to do preventative maintenance on both trucks and replaced them with new based on the engine serial. Now the temp stays at 170 on both trucks. I don't think there is anything to worry about.
    Maybe the newly made thermostats are just different PXL_20210210_204257634.jpg
     
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  10. bad-luck

    bad-luck Road Train Member

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    My first thought would be a thermostat stuck open.
     
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  11. Trucking in Tennessee

    Trucking in Tennessee Road Train Member

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    Old school was to always take them and put them in boiling water. See where they opened. We are getting so much crap from overseas you just don't know anymore. I saw on Amazon they had a regular Stant for $4.95 but a really good one for $11. Geez.
     
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