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Halfpint 8/7/2019

2004 Jeep Liberty Sport 6 Cyl 3.70L


Jeep still overheating 6 cylinder 3.7 L, 04

I recently replaced my radiator. Soon after my Jeep continues to overheat. I have replaced the water pump, electric fan, thermostat, thermal temperature sensor, flushed it numerous times, burped it every time. Heater ,AC works. no coolant leak or smell. Driving 15 to 25 minutes mostly when I go uphill it seems to overheat. I'm pretty sure my thermostat is opening because when I replaced my water pump jeep warmed up, the coolant started circulating as I kept adding more. The only thing I can think of is that I tried to find a thermostat that was a little below the 210 average temp of a Jeep Liberty, and I went for one that said 195 Fahrenheit. Would this make my Jeep overheat, even to the point where it's a 3/4 to max heat on my gauge? I also hear a very slight ticking sound behind my AC / alternator... kind of similar to win a car ticks when it's needs an oil change, but I just recently did that as well. I appreciate any input thanks! (Forum will not let me enter a 3.7 L 6 cylinder)

1 Answer


Jimm 8/7/2019

Loss of coolant because of a coolant leak is probably the most common cause of engine overheating. Possible leak points include hoses, the radiator, heater core, water pump, thermostat housing, head gasket, freeze plugs, automatic transmission oil cooler, cylinder head(s) and block.

Make a careful visual inspection of the entire cooling system, and then PRESSURE TEST the cooling system and radiator cap. A pressure test will reveal internal leaks such as seepage past the head gasket as well as cracks in the head or block. A good system should hold 12 to 15 psi for 15 minutes or more with no loss in pressure. If it leaks pressure, there is an internal coolant leak (most likely a bad head gasket but possibly also a cracked cylinder or engine block).

It is important to pressure test the radiator cap, too, because a weak cap (or one with too low a pressure rating.

1. Perform a cooling system / radiator pressure test when the engine is cold - as a first step to locate the leak.
Obtain a loaner tool / free radiator pressure tester from the local auto parts stores such as Autozone, O'Reilly, NAPA, Advance Auto, or PepBoys. Follow their instructions and pump it to an adequate air pressure 12 -15 psi or the pressure rating listed on the radiator or reservoir cap. Observe the leaks and perform the repair.
Note: do not over pressurize beyond the pressure allowed by the radiator cap, then test the radiator cap as well.

2. Air pockets trapped in the cooling system can cause the engine to overheat. Some cooling systems have air bleed valves built into the system to aid in the removal of air pockets. Advice: For many cooling systems, the method of removing air pockets is to start the engine and allow it to run with the radiator cap off or loose until all the air escapes from the neck of the radiator. For some systems this method is not sufficient, and the manufacturer has installed air bleed valves usually near or on the thermostat housing.


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