Truck won't heat up

Discussion in 'Engine & Performance' started by mok4200, Dec 8, 2016.

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  1. mok4200

    mok4200 Junior Member

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    Truck will not heat up, has brand new heater core and I'm on my 4th thermostat. All started after replacing my plenum gasket. All parts from dodge. Made sure to burp the system and checked all fluids. Any ideas?
     
  2. Ramtech2319

    Ramtech2319 Member

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    Year , engine please
     
  3. mok4200

    mok4200 Junior Member

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    Oops, 2001 5.2l auto 4x4
     
  4. dudeman2009

    dudeman2009 Senior Member

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    If the truck is refusing to get up to operating temperature, you need to verify the gauge reading by either feeling a radiator hose with your hand, or a thermometer. If the radiator hose heats up after about 10 minutes of idle, replace your coolant temp sensor. If the radiator hose doesn't heat up, you need to check for flow from the water pump. That requires taking out the thermostat and running the engine with the radiator cap off. You may be able to test it without removing the thermostat, but there is no guarantee. With the engine running, look into the radiator cap hole and watch the coolant level as you rev the engine by hand. The level should drop when you rev the engine and rise when you let off.

    If it doesn't remove the thermostat and try again, or if its already out, you are looking at a new water pump. You could try flushing it before replacing the water pump.
     
  5. mok4200

    mok4200 Junior Member

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    I drove it around for 30 mins and the heater hoses were hot but not too hot to hold onto. I'm going to try to replace the upper and lower rad hoses then try to take out the thermostat and see what happens, thanks for the advice
     
  6. dudeman2009

    dudeman2009 Senior Member

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    The heater core hoses wont be HOT if the core or one of the adapters/lines is plugged or you're running a thermostat at 180* or less.

    Whats important is the upper radiator hose. We might be on different pages here. Is your cab heat not getting hot, or is the engine coolant not getting hot?
     
  7. mok4200

    mok4200 Junior Member

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    Both. Last week I got a "too cold for too long" engine code and after that I put in my dodge thermostat, same result. The cab also has very very mild heat, would guess maybe 90 degrees blowing. The upper radiator hose I should replace, when I was changing thermostats it was pretty flexible..
     
  8. dudeman2009

    dudeman2009 Senior Member

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    It is a slight possibility, if someone just put straight water in at some point and ran it like that for awhile, that there is a type of scale buildup that is preventing heat from transferring to the coolant. At this point, i'd put in a coolant flush additive and run it without the thermostat until it gets up to operating temp for at least 20 minutes, or about 100 miles, whichever comes first. The flush and reverse flush the engine block and forward flush the rest.
     
  9. alanack6795

    alanack6795 Member

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    Make sure you are installing a Mopar T stat and its being installed the correct way. The thermostat is the ONLY thing that can cause this issue
     
  10. mok4200

    mok4200 Junior Member

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    Spring is in the down position, and it is direct from the dodge dealer. I'm going to take it out soon, and then put it in boiling water to make sure it is opening.
     

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