What burns white onto the head? (not exhaust)

IwantMKIII

WVU MAEngineering
Jun 12, 2007
2,477
0
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Perkasie, PA
Is this coolant or oil? Ive notice it on the rear passenger side of the head(cylinder 6) around the EGR cooler. Very white, caked on powder. My suspicion is in the 90* coolant elbow there but don't see anything visiblibly. I only ever notice smoke coming off the exhast mani towards the accumulation.