Overheating Jeep Grand Cherokee

If the pressure inside the radiator rose enough to crack it, the radiator cap (rated 18 psi) might have been the cause. To reach 220 F even with the fan coming on suggests that the thermostat may have been installed backwards. The thermostat coils should face the engine. To determine coolant flow, the heater hoses will heat up first. To get a blast coolant when opening the cap may be trapped air. I leave the radiator uncapped while running the first time and watch for circulating coolant. It would not be unusual for a water pump that old to have all the impellors corroded away...not pumping. There was even a concern over 2000-2002 Jeep six engine developing a cracked head between #3 and #4. I would try again after purging out the air, and check the radiator cap. That's all I know for sure.