Well I finally got around to messing with my 99 cherokee 4.0L.
It still wont start even with a new battery but I am 100% certain of why that is now.I decided to pull the plugs and look at them as well as try to look into the cylinders.The #3 and #4 plugs were pretty wet and the gap was bridged with a greenish brownish liquid . With a flash light I looked into the #3 cylinder and it if full of what I assume is coolant considering its greenish tint.
I guess I will need to pull the head.Hopefully no other damage has occurred to any other part of the engine.The engine has almost 200k miles on it so I kinda wanted to do a rebuild or at least a swap but I think I will pull the head and see what I can see. It is probably a bad thing but Im guessing that since the jeep has set all winter without running with coolant in the cylinders that the rings are pretty tight so I might get away with just the head gasket.
I am also hoping that since the cylinders are full tat the head is not cracked and just the hg is just blown between between the #3 and #4 cylinders.

Thoughts,comments, warnings about the hg replacement job please feel free to speak out .

 

I'm worried about coolant in the oil pan f-ing your bearings. Better drain that old oil, better yet drop the pan to get it as clean as possible. Good time to plastigauge the bearings, main and con rods.

 

Other than corrosion how much damage can be expected since the engine has not been run much since the condition presented it self? I have had the jeep for about 4 months just sitting.I have messed with it a bit turning it over and trying to get it running but since I have had it it has never actually run.
The kid I bought it from had it over heat on him and he ended up having it towed to his house and parked until I bought it.

I should also mention that although I am sure there must be some coolant in the oil,like I siad it has set not running for a few months and the cylinders are still full of coolant which amazes me that it has not leaked into the crank case by now.

 

Two adjacent cylinders is a common symptom of a bad head gasket. The 0630 head on the 99 is generally pretty hardy.

BUT, whenever you pull a head off after an overheat, it is money well spent to take it to a machine shop and have it checked for cracks and to be sure it isn't warped before you put it back on.....