Question about 2004 Chevrolet Monte Carlo

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I just replaced my 3.4 liter motor in my 2004 monte carlo and I need to figure out why the other motor over heated and blew a head gasket. Before I replaced the motor the heater was blowing cold air and now its blowing warm air out the passengers side and cold air out the drivers side. At normal running temps 1 hose to the heater core is hot and 1 is cold. I've backflushed the core and put a hose to it to make sure there was no blockage. The coolant sensor is working fine and I've got adaquate coolant. I want to replace the heater core but if that dont solve the problem then ill be back to square 1.

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A little tip is to "vent" the topmost hot hose whith the engine running to clear any trapped air in system.....loosen the clip,whilst under pressure,wear rubber bloves cos it bloody hot.......

Posted on Sep 10, 2010

  • U2_fan Sep 10, 2010

    I did bleed the system really good so all air is out. The more I read about other people with the same problem the more I am believing its just a poor design. People are spending thousands of dollars trying to get the system to work right with no results. Is it common to hear the sound of water sloshing when I take off from a stop light?

  • geoff hunter Sep 10, 2010

    the water sloshing about is in the heater matrix,which is lower than the topmost hose,
    so you still have air in the system....try removing the topmost heater hose,


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Hi, this may be the car thermostat. this normally is housed near the top of the engine. usually a hump with a large water hose clamped to it (some have small water hose also). do your car have climatized heating. if the settings for the driver is warm the passengers setting may be cooler. gerry

Posted on Sep 10, 2010

  • U2_fan Sep 10, 2010

    I've replaced the thermostat and yes I have climate control. Passengers side works on either setting but drivers side is just cold air.

  • gerald white Sep 10, 2010

    hi, then the problem is the HEATER COTROL FLAP is not working


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