1998 Jeep Cherokee Erratic overheating with AC on

JESTER723

MEMBER
1998 JEEP CHEROKEE
6 CYL
2WD
AUTOMATIC
110,000 MILES

I changed the lower radiator hose recently after it burst. Since then the temp needle will creep to 220 then shoot to redline, after I turn off AC and turn up heat the needle will fall quickly back to 220. I changed the sensor and the thermostat. I've been told there's air in the system and to bleed it. When I open the radiator cap (cold), it is full and the reservoir is full, when I start the engine the coolant immediately rises and flows out the radiator. I pulled into a shop on Monday and the radiator temp was 40 degrees higher at the top than the bottom and the heater hoses had a big temp difference too. I'm thinking there's a restriction in the radiator. Does that sound right or is there something else that could be happening?

1 Reply

BLUELIGHTNIN6

MECHANIC
16,542 POSTS

Hello and thanks for donating

many things can cause engine overheating such as inoperative radiator fan(s), stuck thermostat or cracked head gasket. The first place to start diagnosing overheating is with the thermostat. Remove it and test to ensure it is opening properly. Also make sure radiator fan(s) come on properly. If it is OK, and coolant is full, then there may be blockages in the coolant system or the cylinder head gasket may be bad. With a bad head gasket, you would normally see coolant mixed into engine oil or vica versa.