Joe,
Wait a doggone minute! You've told me you don't know squat about wrenching! If that's the case, how did you hit that whole enchilada right on the head :shock: ?!
Yep, that's exactly right. It was indeed the right rear cylinder and the corner headbolt was hand tight only. Not only is the water passage and cylinder space very close, but the original head gasket on the ZZ4 is junk

. At least when compared to the Fel-Pro replacement (which is stock on the 502).
With this being the case, it should be recommended that checking head bolt torque occasionally ain't a bad idea. Lots easier than the ugly job of replacing the head gaskets and even uglier to clean the mess. That goop of oil and water/coolant mixing makes icecream EVERYWHERE. Quite an ordeal just to clean it all up

. When considering the damage that can be caused to cylinders, pistons, bearings, etc., it makes one think seriously about checking.
Again, very intuitive Joe. Best regards...
Elliot 8)