DD15 low coolant temperature

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by DrFlush, Nov 22, 2021.

  1. DrFlush

    DrFlush Road Train Member

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    I have a 2014 Cascadia with a DD15. Coolant temps won't go above 150 idling, thermostat is working properly and sensors are reading accurate. Anyone have any ideas?
     
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  3. Opus

    Opus Road Train Member

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    Mine hangs at 100 +/- always.
    Same truck, same engine.
     
  4. Opus

    Opus Road Train Member

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    My bad....200
     
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  5. DrFlush

    DrFlush Road Train Member

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    Mine use to, now I have a aftertreatment mil but no codes and low temps.
     
  6. Goodysnap

    Goodysnap Road Train Member

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    Maybe I’m missing something here…….How do you know the thermostats are working properly?

    It sounds like they are opening too early to me. Shoot the rad pipes with a temp gun. Upper hose should be cool until they open. Engine fan is off?
     
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  7. Opus

    Opus Road Train Member

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    Was going to say, but I was so far off the first time, I was reluctant.
    That said, the gauges in my Cascadia are so completely unreliable I wouldn't sweat it unless something else tells you that something is wrong.
     
  8. jason6541

    jason6541 Road Train Member

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    Have you tried bumping idle up while idling to 900 what they call for. I would say thermostats May be faulty or bad gauge reading. Only way to know for sure is pull t stat and test them.
     
  9. DrFlush

    DrFlush Road Train Member

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    Temps were shot at inlet and outlets already. Fan is off but free wheeling some. Idle was at 900 and then 1300. Same results. Took the old thermostat and put it in an oven, actually opened and closed perfectly. Cardboard in front of the radiator brings temps up but its been 50 out. Shouldn't have to block the radiator at that temp.
     
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  10. Rideandrepair

    Rideandrepair Road Train Member

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    Need to boil stats, check water temp with a thermometer when they open, and close. Sounds like one is sticking open. Might even have 160’s or 170’s. Sometimes once they get too hot, they will work erratically. So I’ve heard. Get some 180s or 190s if so. Whatever it calls for. If they check out. Should be good. Maybe gauge or sensor? Sometimes an early sign of head gasket trouble, especially if you’re losing heat to the cab. Should still get warm/hot at 150. Can’t trust the gauges.
     
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