Cab heat issue

Discussion in 'Trucks [ Eighteen Wheelers ]' started by skman, Dec 2, 2022.

  1. skman

    skman Light Load Member

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    108
    Aug 26, 2013
    Saskatchewan
    0
    I've got a 2008 Western Star 14L with a cab heat problem.
    When sitting an idling (cold winter days) at up to 1000 or so....engine temps will still drop to 130-140. Of course, then my cab heater temps also drop to a point where it feels like lukewarm air coming out.
    It's a big bunk so it starts to cool off in there quite a bit.
    When driving down the highway, it will rarely kick on the fan with the engine temp usually hovering around 185-190 and the cab heat will get warmer but still not great... especially when it's a cold Saskatchewan winter day (even with a full winter front).
    It's always had this problem but I've just learned to live with it. But I have drivers in it and they don't like driving it...lol
    It had a new head put on a few months ago so I don't think that's the issue...as its been like this for years. So I was going to change thermostats to see if that will help.
    Not sure what's in there right now...but which would be the best temp thermostat to keep engine warmer and cab heat hotter??
     
    austinmike Thanks this.
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  3. zinita17601

    zinita17601 Road Train Member

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    Aug 19, 2010
    lancaster pa
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    U may have two separate issues,a bad thermostat and a bad heater valve.
     
  4. Rideandrepair

    Rideandrepair Road Train Member

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    Sounds like one of the two thermostats is stuck open.
     
    skman and austinmike Thank this.
  5. skman

    skman Light Load Member

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    Aug 26, 2013
    Saskatchewan
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    That's what I was wondering...and figured I'd try changing them.
    What temp thermostat would you recommend?
    It doesn't get crazy hot here in the summer, no mountains to climb...but it does get cold in the winter
     
    Rideandrepair Thanks this.
  6. Espressolane

    Espressolane Road Train Member

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    Nov 21, 2009
    Just south of the north 40
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    Usually if a thermostat is stuck open, it tends to cause overheating.
    It does sound like flow to the heater cores is restricted.
    Sounds like a winter front could help out.
     
  7. skman

    skman Light Load Member

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    108
    Aug 26, 2013
    Saskatchewan
    0
    Yeah I've got a full winter front on. Never thought about plugged heater core mainly because I figured it's the engine temps at idle making it blow cooler air. It blows pretty warm air when engine temps are 175-185
     
    Rideandrepair Thanks this.
  8. uncleal13

    uncleal13 Road Train Member

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    Apr 9, 2009
    Humboldt, Sk
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    I had a 2013 4900SF, first two winters here in Saskatchewan cab was cold, side windows would frost up going down the highway, would only clear when stopped.
    Third winter I unhooked the cab heater hose off the heater control valve to flush out the heater core.
    I happened to glance at the port of the valve and saw that it was mostly closed, only open about 1/8”. I knew my cab setting was full heat. I double checked and confirmed it was selected hot.
    I got looking at the valve. The arm were the control cable was attached was mounted into a hole that was too far from the body of the valve so it had lots of leverage but didn’t rotate the valve very far.
    I drilled a hole into the arm about half way down and installed the cable.
    It was now harder to turn the control knob, but the valve now would rotate fully open.
    After that the cab was roasting hot, and the windows stayed clear.
     
    Rideandrepair, ducnut and skman Thank this.
  9. skman

    skman Light Load Member

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    Aug 26, 2013
    Saskatchewan
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    Hmmm...I'm gonna check that out. Thanks
     
    Rideandrepair Thanks this.
  10. ducnut

    ducnut Heavy Load Member

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    Dec 31, 2010
    Paradise
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    Whatever the factory thermostat temp rating is what you want. Though that engine probably doesn’t have near the complexity of the latest stuff, the ECM is still going to expect to see temps in a specific range. I wouldn’t deviate from that.

    It’s common for engines to lose heat, when not doing work. All that can be done is to bump the idle even more or add an auxiliary bunk heater.

    I agree with the others, you definitely need to be looking for heater control valve issues and plugged heater cores. I’ve experienced both. With a truck that old, if the heater cores have never been changed, they need to be.
     
    Rideandrepair Thanks this.
  11. Rideandrepair

    Rideandrepair Road Train Member

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    Thermostats stuck closed, restricting circulation causes overheating. Stuck open, engine will run cold in cold weather, especially at an idle.
     
    slim shady Thanks this.
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