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      07-19-2020, 08:02 PM   #6
BB_cuda
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Drives: 2011 335D Msport, 2013 X5D
Join Date: Nov 2011
Location: Clear Lake, Texas

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Idle car with reservoir cap off and look at the little stream peeing into the reservoir. When you see no bubbles in the stream, it should be purged.

To be fair, I did this for only a thermostat swap versus a motor swap so obviously you have way higher potential for entrapped air. The dealer mechanic told me to run the heater while letting it idle with the cap off to push coolant through that coolant circuit too. Good luck and maybe it is the sensor. I wonder if there is a resistance spec on the sensor to check.
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