Got it tore down and no cracked head or block, thank god lol. The gasket was shot on the other hand.

 

New gaskets and its almost back together, just gotta throw the rest on and flush the radiator, hopefully ill be back behind the wheel tomorrow. A week without the xj is hell! Even the gf misses the jeep! Win win situation haha.
Next ima change the oil to get anything left in the motor out. It sucks finding out u have to tear ur motor apart, but its amazing to see it go back together.
I wish I had the time to just tear down the motor to just clean everything (which was nice cuz it needed it) and replace gaskets, but I just can't wait to drive it again!

 

This happened with me, not sure why it originally happens but you have to flush your radiator really really well. Like drain it, run water through it till it starts coming out clear. When I say run water through it I mean take off the radiator cap, drain ****, and the other black cap on top of the coolant line next to the head and shove a hose in the radiotor cap and just let it blow through the whole system till its coming out clear from the other two holes. Then fill it with water and drive it around for a few miles and repeat the last step. Then put a bottle of radiator flush in it, fill the rest with water and drive it through like half tank of gas. Drain and run the hose through it again like twice more, running clean water through for a few miles between the hose flushes again. Then fill with clean coolant again and youll be alright. This "mud" is actually corrosion off the inside of your radiotor, its basically rust particals and coolant mixed together making muddy concistancy.

 

The XJ rad is impossible to visually inspect internally......the tanks must be removed from the core in order to do so. Unless it's pulled apart for inspection, one does not know how many rows (from the bottom up) have been plugged off with solids. Once a row/tube is plugged off, no amount of flushing is likely to clear it, hence the term "rodded out" which is done by rad shops. Just because flush water is freely flowing out and clear doesn't mean all (100%) of the rows top to bottom are flowing freely. The top half of the rad could be flowing freely but the bottom half could remain plugged off. 1/2 of a already ridiculously small rad is not a good thing. The mud/brown crud inside the rad is rust from the cast iron block/head due to weak neglected antifreeze/coolant. The small coolant passage ways in the rad is the natural place for particles to collect/accumulate.