My MY99 XJR, 150,000, miles started losing a little coolant, then
had steam from one side exhaust and finally hydrolocked. Removing
the plugs I found it was the 2 B cylinder. Anyway, once I got the
head gasket out, it seems to have a strange failure mode. If you
can see from the picturs, the cylinder seal ring is pushed inward
and burned. There is a distinct mark for the edge of the cylinder
or maybe where the piston hit it. One side has a tiny crack. I
had no overheating or major loss of coolant since I have owned the
car (20,000 miles). I believe it might have been a failure to
compress properly when it was orriginally tightened, and then the
heat finally cracked thru- Any ideas?