Just bought my latest G/cherokee 4.7L Overland with 48000 FSH miles and noticed a slight misfire. No1 sparkplug sheared whilst trying to remove it so took to a specialist to sort. On removal of the clyinder head the full horror began to show, a piece of the combustion chamber had broken off next to the plug and the piston was at a slight angle which was later found to be caused by the piston skirt breaking up. Obviously the kind man who sold me the problem does not think he should cough up any of the £2000.00 to replace the piston and head ******* Thanks Matey. Has anyone ever heard of this problem before with the H.O. engine, nobody in the UK has.