2006 Jeep Liberty Overheat 3.7L

Maintenance/Repairs
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1

I have a 2006 Jeep Liberty 3.7L that has a temperature gauge on the dash that reads an overheat when driving. The oil looks normal, there is no white smoke, no bubbling from reservoir. I have replaced the following:
Radiator
Thermostat
Water Pump
Coolant Temperature Sensor
Coolant Reservoir Tank

I am not leaking any coolant and the reservoir level has been fine. I have let the vehicle idle for 20+minutes, with no overheat. When I drive it around, the temperature gauge will read an overheat. When I stop the car and pop the hood, the engine is not overheated and both rubber hoses to/from radiator are flowing the coolant. The only thing that will bring the gauge down is turning on the heater full blast. Could this be the gauge itself being bad? Could it be a short in a wire somewhere? I had thought maybe a head gasket, but have no symptoms of a head gasket. Any ideas are welcome as this is getting more expensive than its worth to troubleshoot this vehicle.

2

Check the color of the transmission fluid. If the transmission fluid is black the transmission is running hot.

Since the cooler for the transmission fluid is inside the radiator, an overheating transmission can cause the engine to overheat.

Tester

3

Try a pressure test and new radiator cap.

4

The electric fan is running, correct?

5

Yes, the fan turns on just fine, but the gauge still reads the engine as hot.

6

Most of the time these “I’ve changed everything” overheating stories end up with a new head gasket or two.

7

When you say the gauge reads the engine as hot, do you mean the needle is in the red? How far up the gauge is the needle? Most Chrysler products I have owned, the normal highway temp is 5/8 to 2/3 up the gauge.
Why did you replace all those things without a good diagnosis? I have never seen real overheating without loosing coolant.
Get is hot and pull over and read various spots on the red with a laser temp gun. Pressure test the system and get a dip kit to check for exhaust in the coolant.
Do this after checking your tans fluid as Tester suggested.

8

Have you bled the air out of the system? Air will cause it to overheat. Running the heater is like adding an extra radiator.

9

Other’s here with similar problems are sometimes able to fix it by simply replacing the radiator cap. It may not be holding pressure like it should. A radiator shop could test the current cap, or you could just replace the cap and cross your fingers. You could get lucky.

10

These 3.7s have a reputation of being problematic(I’m waiting for mine to self destruct) really a few design issues with these engines,but some remanufacturers claim to have solved all the design shortcomings,so I wish you the best and hope its not cylinder head problems-Kevin