1998 discovery. had exhaust gas coming through expansion tank and suspected HGF. Took head of and saw white milky blobs on top of two pistons, also a hard brown substance that looks like it ran down the bore about 2 inches, any idea what this is or is it part of the HGF. A bit of corrosion on the head itself, hope its still useable.

changed head gasket, and all is well. didnt bother getting the head skimmed as there was no warping on the head.