In this video, you will find the exact location of the thermostat and its housing on the 4.0L V6 engine. If your engine is overheating, your heater is blowing freezing cold air, or you are getting ready to replace a leaking factory plastic housing, knowing exactly where it sits will save you a lot of time and effort.
How this video helps you: On the 4.0L Cologne V6 engine, the thermostat is housed inside a notorious plastic assembly located right at the top front of the engine block, tucked directly underneath the intake manifold throttle body and behind the alternator. This quick and clear visual guide points out its precise position. You can see how the upper radiator hose and heater bypass lines connect to it, and get a clear view of the mounting bolts and temperature sensors so you can plan your teardown easily.
💡 Pro Tip: The factory composite (plastic) thermostat housing on this specific 4.0L engine is highly prone to cracking, warping, and leaking fluid into the “valley” of the engine block over time. If you see a puddle of coolant pooling under the intake manifold, this housing is almost always the culprit!
Common symptoms of a bad Thermostat or Leaking Housing: The thermostat regulates the flow of engine coolant to maintain the perfect operating temperature. When the thermostat fails or the housing cracks, you will see these warning signs:
- Engine Overheating: If the thermostat gets stuck in the closed position, coolant cannot reach the radiator, causing your dashboard temperature gauge to spike into the red zone within minutes of driving.
- Engine Running Too Cold / Slow Warm-up: If the thermostat is stuck open, coolant constantly cycles through the radiator. The engine will struggle to reach its normal operating temperature, and your dashboard heater will blow lukewarm or cold air on chilly days.
- Visible Coolant Leaks & Sweet Smell: A cracked plastic housing will slowly drip engine coolant down the front of the block. You will notice a sweet smell after driving or spot a green/orange puddle forming right underneath the water pump area.
- Check Engine Light (CEL): If the engine takes too long to warm up because of a stuck-open valve, the computer will trigger code P0128 (Coolant Thermostat Regulating Temperature Below Thermostating Range).
Watch the video to see the exact location and spot those common leak points before you start working!