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Merchant Automotive Engine Coolant Thermostat Kit, Duramax | 2001 - 2010


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Engine Coolant Thermostat Kit, Duramax | 2001 - 2010
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Product Information

Duramax Engine Coolant Thermostat Kit
If you are experiencing your Duromax diesel truck not heating up or overheating, you could be experiencing a stuck thermostat. Over time, thermostats can stick open or closed, causing heating or cooling issues on your 2001-2010 Duramax 6.6L V8 truck. This thermostat kit will include a front and rear thermostat along with the oil fill tube seal and upper radiator pipe seal to complete the install.


The front thermostat on a Duramax Diesel engine is mounted in the forward position of the thermostat housing and is identified by its symmetrical shape. It opens at 185 degrees, allowing coolant to flow to the radiator. 


The rear position thermostat on a Duramax Diesel engine is located toward the fire wall. It's identified by its offset design and has bleeder valves built in. It opens at 180 degrees, allowing coolant to flow to the radiator.



  • Direct Replacement
  • Helps Restore Cooling System Functionality
  • All In One Kit


  • Comes With Needed Seals
  • Front & Rear Thermostat Included
  • OEM Temperature Functionality

What's In The Box

  • Rear Thermostat
  • Front Thermostat
  • Oil Fill Tube Seal
  • Upper Radiator Pipe Seal

Symptoms Of Stuck Thermostat

When a thermostat becomes stuck, it can become stuck open or stuck closed, both producing opposite symptoms. Let’s take a look at what symptoms you may experience from each.


Thermostat stuck open - In the event that your thermostat is stuck open, coolant will always be flowing throughout your cooling system. This means that your truck will most likely take awhile if and when it reaches temperature. The thermostat is designed to stay closed until the coolant has reached operating temperature, then it opens to start cooling.


Thermostat stuck closed - A stuck thermostat will allow the truck to reach operating temperature, but will not open to allow for the coolant to flow through the cooling system. This will most likely result in an overheating issue that could drastically hurt your engine.

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