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StefStemp
StefStemp 8/15/2012
1999 BMW 528i Base 6Cyl2.8L - Body & Interior
My car is overheating and replacing the coolant tank and filling it with coolant did not work. What could be wrong?
There was a noticeable hole in the coolant tank so I of course took it in and a new one was installed but it overheated again before I even got it home
3 Answers
  • HouseCallAuto
    HouseCallAuto 8/16/2012
    Did you bleed the air out by opening the air bleed screw (black plastic screw) on the top of coolant tank?
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  • Mark A.M.D
    Mark A.M.D 8/16/2012
    The system was probally not Bled correctly, Air inside the cooling system will cause an 'Air Lock' and prevent coolant from circulating and cooling. Run the engine with the cap off and coolant level on max and watch to see if any air bubbles come through, Once the engine is up to operating tempreture the thermostat will open and the fans (if electric) will engage. All of the air should be expelled by this stage. Replace the cap and test drive the vehicle, If it still overheats there is obviously another issue at play.
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    Mark A.M.D
    StefStemp 8/16/2012
    Thanks for your quick response. I actually talked that over with the mechanic before i drove it and he assured me he tested the air lock and that was clear. My only thought is it could be a problem with my thermostat
    Mark A.M.D
    Mark A.M.D 8/16/2012
    It definitely is probable, Some BMW models run a thermostat in the bottom of the header tank. Usually these are replaced with a new tank. I would personally take the vehicle back and get them to check it throughly before throwing parts at it.
  • HouseCallAuto
    HouseCallAuto 8/16/2012
    A bad thermostat is not uncommon on BMW.
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