Originally Posted by Overland1
What was causing the specific cylinder head problem (assuming it was cracked), and was it resolved in the newer Jeeps?
One of the issues was the valve seats on one cylinder (I forgot which) would fall out because the head was getting a hot spot from the design of the head itself. There is no exhaust manifold so the hot exhaust gases have to flow right past the next cylinder. That next cylinder would get so hot the aluminum expanded too much and the steel valve seat would lose press fit.