What would cause a 2001 jeep wrangler 4 Liter to overheat bubbling gurgling and spewing coolant into and out of the overflow tank?

Answer 1

Thermostat stuck closed or only partially open: check upper radiator hose when Jeep is at normal operating temperature (180-200 degree F). If upper radiator hose is cold, thermostat is stuck closed, warm it may be partially open or need of replacement. Hose should be hot. Check for leaks in coolant system, especially in the rubber hoses. If coolant is bubbling & overflowing as if under pressure & does this more so after you turn the engine off, this could be a leak in the coolant system which is causing the coolant system to dry in air like a vacuum, causing the system to be more pressurized. Also check&/or replace Coolant Tank cap as it might not be releasing the excessive pressure in the coolant system. Or, headgasket leak could be causing build of pressure of combustion to get into the coolant system and/ or similiar. Also check to see that Radiator Fan is turning on when engine gots hot (around 195-210 degrees F) If not, check and test the fan & Fan Relay. NOTE: I saw quite a bit of this on an outing where the drivers put their jeep through a mud hole and coated the radiator. An hour or so later they were overheating because they fins of the radiator were unable to cool through the coating of mud.