Losing coolant when heating is on - 2.0 TDI 140PD BKD


Registered User
Jun 26, 2014
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So as the title says, after owning a notorious BKD for 3 years and lived in belief that my cylinder head is porous, I discovered that I am not losing coolant unless I turn on heating / blowing.

With heating off, the coolant level stays the same for hundreds of miles, whereas when I turn it on, it disappears after only 300 miles or so.

Could it be the small radiator in the cabin? If so, can it be replaced without removing all the plastic bits from my interior (as a couple of people told me all of the front plastics of the interior including speedometer area need to go out in order to do this)?