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AutoMD Member
AutoMD ... 8/1/2014
2011 Nissan Altima S 4 Cyl 2.5L - Engine
Why is there a greasy substance on the windshield above the defrost vents?
Was thinking maybe heater core bad?
1 Answer
  • CVO
    CVO 8/2/2014
    Check the radiator coolant level, a lack of coolant could be the cause of a bad heater core.
    AutoMD Member 8/2/2014
    Thanks, are you saying that filling it will cure the residue problem, or that the heater core is already bad and causing this problem?
    CVO 8/2/2014
    Perform a cooling system / radiator pressure test when the engine is cold - as a first step to locate if the heater core is bad
    Obtain a loaner tool / free radiator pressure tester from the local auto parts stores such as Autozone, O'Reilly. Follow their instructions and pump it to an adequate air pressure 12 -15 psi or the pressure rating listed on the radiator or reservoir cap. Observe the leaks and perform the repair.
    Note: do not over pressurize beyond the pressure allowed on the radia cap.
    AutoMD Member 8/3/2014
    Thanks, I have seen no puddle on the ground at any time. Wouldn't it be leaking under normal driving if the heater core was bad?
    CVO 8/3/2014
    Check the radiator coolant level. A lack of coolant is considered a leak has occured. A tiny hole in the heater core wouldn't deliberate much of a coolant, but enough to create a greasy substance on the windshield. A heater core with a large hole will flood the floor carpet
    AutoMD Member 8/4/2014
    Checked the radiator first thing morning,it was completely full.
    CVO 8/4/2014
    PRESSURE TEST the cooling system, it will reveal internal leaks in the heater core.A good system should hold 12 to 15 psi for 15 minutes or more with no loss in pressure. If it leaks pressure, there is an internal coolant leak.
    AutoMD Member 8/5/2014
    Care to guess what a heater core repair might cost me?
    CVO 8/5/2014 listed the heater core for 47.00 dollars + shipping, then the repair is 4 hours or a little more.

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