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Int’l Durastar cabin heat not working well.

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by wlhequipment, Oct 29, 2022.

Page 1 of 2
  1. Oct 29, 2022 #1
    wlhequipment

    wlhequipment Bobtail Member

    49
    19
    Aug 16, 2022
    denver, co
    0
    Hi folks
    I have a 2006 4300 with bad cabin heat. Thermostat gets to 170, and the heat coming out is just barely warm. Never gets hot. I’ve replaced the blend door actuators, all doors open and close. Filter is removed for now. All other functions seem to be working. Heater core was just cleaned and flushed out. Hoses going to and from heater core are about the same temp, but they don’t seem as hot as they should be. According to the owner, that’s how it’s been for years. Any ideas?
     
    wlhequipment, Oct 29, 2022
    wlhequipment, Oct 29, 2022
    #1
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  3. Oct 29, 2022 #2
    BoxCarKidd

    BoxCarKidd Road Train Member

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    A little different but are those not similar to a radiator with a common header on each side?
    Flow is not through a continues line. Impossible to surely flush them out.
    I washed some cores out that I know had stop leak used in the system. Used a hot water pressure washer back and forth in both heater hoses ( no spray tip ). Blow or go. They did not explode and cleared out.
    Worked on a new 1986 Pet with that problem. The heater hoses were hooked up backwards. Still do not understand that myself.
    Thank one of your hoses is 5/8.s and the other is 3/4,s so that would not be your problem.
     
    BoxCarKidd, Oct 29, 2022
    BoxCarKidd, Oct 29, 2022
    #2
  4. Oct 29, 2022 #3
    Lazer

    Lazer Road Train Member

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    Have you changed out the valve(s) on the block?
     
    Lazer, Oct 29, 2022
    Lazer, Oct 29, 2022
    #3
  5. Oct 30, 2022 #4
    wlhequipment

    wlhequipment Bobtail Member

    49
    19
    Aug 16, 2022
    denver, co
    0
    I don’t know specifically how the radiator works inside. To be honest, I took that whole rack to my radiator guy for cleaning and testing when I inframed the engine. I think it’s possible the heater core hoses are backwards, I think they’re the same size, but I don’t see how that would change anything, and I really don’t see how the hoses could be connected to the wrong place on the engine, but I’ll certainly double check.
     
    wlhequipment, Oct 30, 2022
    wlhequipment, Oct 30, 2022
    #4
  7. Oct 30, 2022 #5
    wlhequipment

    wlhequipment Bobtail Member

    49
    19
    Aug 16, 2022
    denver, co
    0
    What valves?
     
    wlhequipment, Oct 30, 2022
    wlhequipment, Oct 30, 2022
    #5
  8. Oct 30, 2022 #6
    BoxCarKidd

    BoxCarKidd Road Train Member

    4,525
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    Aug 26, 2014
    0
    Bad heater valve? Hose from valve goes to top of engine.
     
    BoxCarKidd, Oct 30, 2022
    BoxCarKidd, Oct 30, 2022
    #6
  9. Oct 30, 2022 #7
    Lazer

    Lazer Road Train Member

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    Jan 22, 2017
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    The water valves that the heater hoses connect to on the engine.
     
    Lazer, Oct 30, 2022
    Lazer, Oct 30, 2022
    #7
    BoxCarKidd Thanks this.
  10. Oct 30, 2022 #8
    wlhequipment

    wlhequipment Bobtail Member

    49
    19
    Aug 16, 2022
    denver, co
    0
    Hah! When you guys said there was a valve, I got all excited and ran out there. There’s no valve I can see. I attached a couple pics of where the hoses exit the engine. Did I miss it? I swear if there’s a valve I missed, I’m going to feel pretty dumb :)
     

    Attached Files:

    wlhequipment, Oct 30, 2022
    wlhequipment, Oct 30, 2022
    #8
  11. Oct 30, 2022 #9
    Lazer

    Lazer Road Train Member

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    Jan 22, 2017
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    Follow both heater hoses from the firewall area, to the engine block. There ‘should’ be a water valve on at least 1 of the engine(block) connections.
     
    Lazer, Oct 30, 2022
    Lazer, Oct 30, 2022
    #9
  12. Oct 30, 2022 #10
    Lazer

    Lazer Road Train Member

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    Jan 22, 2017
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    You mention temp gets to 170? Is that as high as it ever gets? If so, the engine is running too cold, a new thermostat may be in order. Diesels nowadays run 195-205 degrees. That 25-30 degree differential can make a lot of difference as far as cabin heat.
     
    Lazer, Oct 30, 2022
    Lazer, Oct 30, 2022
    #10
    BoxCarKidd Thanks this.
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