How to replace a thermostat housing in a Jeep wrangler?

How to replace thermostat housing in Jeep wrangler?

All liquid-cooled cars, including jeep wranglers, have a small device called a thermostat. In Jeep wranglers, it is located between the engine and the radiator. The thermostat works by maintaining a minimum operating temperature of your wrangler’s engine.

When you start the engine, the coolant and antifreeze mixture is maintained until the engine reaches the specified temperature. Then after the engine reaches this temperature, the coolant will be released to the radiator.

The radiator cools the coolant, which is then directed back to the engine, which keeps it at the recommended thermostat temperature and prevents it from overheating.  

The thermostat, just like any other component on your wrangler, is prone to damage. You might do something that will lead to its damage without knowing it. Here, we’re gonna see how to replace thermostat housing in Jeep wrangler and following are ways in which the thermostat can get damaged.  

  • Engine overheating  

The internal components of the thermostat are only made to handle certain temperature levels that are similar to the engine’s maximum operating temperature. If the engine overheats, it will also cause the thermostat to overheat and will fail after a short while. The internals will get damaged, and you will have to get a new thermostat as you cannot repair a thermostat.  

  • Age of the thermostat

Regardless of how well you maintain your wrangler, some components, such as the thermostat, are not meant to last a lifetime since they are in constant use. The thermostat experiences change in temperature being constantly heated and cooled, and the internal components will wear out due to such conditions.  

  • Improper installation 

Installing a thermostat requires some skill and precision. One step is done wrongly or skipped will result in thermostat failure even before you drive your wrangler.

Some major mistakes are installing the thermostat backward, which puts the temperature sensors towards the radiator and not towards the engine. It will still work, but the risk of overheating the engine is high.  

The other mistake people make installing the bleeder valve upside down, which prevents hot air from bleeding out of the thermostat’s cooling system. This means that the internals will overheat, eventually leading to thermostat failure.  

  • Bad coolant 

The coolant is among the fluids in the engine, together with engine oil and automatic transmission fluid if your wrangler is automatic. When either or both of these fluids come into contact with the coolant, it turns into a sludge that can get inside the thermostat.

When this happens, the thermostat temperature sensors are blocked, and they can’t read engine temperature correctly.  

The engine will overheat if the temperature sensors can’t read temperature correctly due to temperature reading delays. When the engine overheats, the thermostat also overheats, damaging the internals.  

How to replace a thermostat housing in a Jeep wrangler?
  • Factory error  

This rarely happens, but factory error is common among most mass-produced products such as thermostats. But most sellers issue a warranty period for a couple of years if the issue with your thermostat is because of a factory or handling error.  

How to know if the thermostat is Damaged?

There are signs you should note as early as possible before a faulty thermostat causes damage to the engine.  

  • Cabin temperature changes 

If your AC is off when driving yet the cabin is awkwardly hot, this is probably because of an overheating engine. Hot air from the engine gets to the cabin through the vents in the firewall and into the cabin. When this happens, check your thermostat and install it correctly or replace it if it is faulty.  

  • Odd temperature readings 

After starting the engine and letting it run for a while, the temperature gauge should read somewhere between the hot and cold temperature indicators. If it reads either hot or cold, there must be an issue with the thermostat temperature sensors or the temperature gauge itself. Ensure you get both checked just to be sure.  

  • Coolant leaks 

A faulty thermostat will definitely fail to open the valves to let the coolant into the radiator; thus, it will leak when it becomes too much at the valve opening. This mostly happens when the temperature sensors are faulty, or the thermostat is installed wrongly, with the temperature sensors facing the radiator instead of the engine.  

  • Check engine light comes on  

The engine light comes on due to a couple of reasons that might cause an engine malfunction, one of them being a faulty thermostat that will definitely cause the engine to overheat. When it comes on, ensure you inspect everything that might cause the engine to malfunction, including the thermostat.  

Can you drive without a thermostat on Jeep Wrangler? 

Some wrangler owners drive their wranglers without the thermostat, which is possible but not recommended. The role of the thermostat is to get the engine to the required operating temperature then keep it at that temperature by regulating the coolant flow between the engine and radiator.  

The engine will not get to the required operating temperature without a thermostat as the coolant will be continuously flowing.

How to replace a thermostat housing in a Jeep wrangler?

The engine will never get to the required operating temperature meaning that it will burn more fuel, especially if you are driving in winter weather conditions. You’ll notice a high rise in fuel economy because of this, and you’ll definitely want to have the thermostat installed.  

How to replace the thermostat in jeep wrangler? 

Removing the air intake hose, temperature sensor, and radiator hose.

  • Open your wrangler’s hood and secure it with the hood latch. Ensure your engine is cool before you start working around the engine bay.  
  • Remove the engine cover, then remove the air intake hose from the air filter box by removing the two bolts and clamps that secure it into place.  
  • Remove the thin radiator flow hose from the clips near the bolts you have just removed. You can remove the hose completely, but there is no need to.  
  • Remove the air intake hose completely, which will reveal the temperature sensor under it, then remove the temperature sensor by pressing the tab on the wiring harness.  
  • Find a container to drain the coolant into and place it under the upper radiator hose clamp that attaches to the thermostat. Find a thick dry piece of cloth to cover the timing belt, then open the radiator cap to release any pressure in the cooling system.  
  • Using a pair of pliers, squeeze the hose clamp on the thermostat housing and push it down towards the radiator hose.  
  • Carefully remove the radiator hose and direct it toward the container you had laced underneath to drain the coolant.  

Removing the thermostat 

  • Using a wrench socket and extension, remove the bolts holding the thermostat to the engine block reposition the container near the thermostat as more coolant with drain when you remove it from the engine block.  
  • After removing the thermostat, check if the gasket came out with it and if it didn’t remove it from the engine block as the new thermostat already has a gasket mounted on it.
  • Ensure you clean off the gasket pieces, then wipe the thermostat mounting point with a clean cloth to prevent leaks. 

Installing the new thermostat  

  • Insert the new thermostat and replace the top and bottom bolts that secure it onto the engine block but do not over-tighten them.  
  • The bleeder screw on the thermostat is tightened, so you have to loosen it a bit.  
  • Push the radiator hose into the thermostat, then push the clamp to the near end of the hose that is on the thermostat.  

Mplus Coolant Thermostat Housing Fits 12-17 for Jeep Wrangler / 18 for Jeep Wrangler JK 3.6L

  • This premium quality thermostat has high quality, durable and reliable housing under extreme conditions with high resistance against temperatures.
  • The functions of this thermostat will get the engine to heat up to its optimum temperature as quickly as possible, and then keep the engine at its optimum temperature for a long time.
  • Also, it is perfectly compatible for Jeep Wrangler JK 3.6L V6 engine and comes with 2 years or 40000 miles warranty.

Filling in coolant into the radiator 

  • You now have to fill in the coolant. If you bought the non-concentrated one, you don’t have to mix it with water, but if you have the concentrated one, ensure you mix it with distilled water in a 50/50 mixture.  
  • Ensure you measure it correctly using the recommended capacity measurements in the owner’s manual, then fill it into the radiator using a funnel. Fill the radiator until you see coolant on the neck of the radiator the close the radiator.  
  • Tighten the bleeder screw on the thermostat but do not over tighten it, then remove the container that has the old coolant.  
  • Reinstall the air intake hose and ensure you get all the screws and clamps.  
  • Get into your wrangler, start your engine, let it run for a while, and check underneath for any leakages. Check the temperature gauge, and if it stays in the middle between hot and cold readings, you are set to go.  
  • Open the radiator cap and add in more coolant as the level will drop when the engine reaches operating temperature. Add coolant until it reaches 1 inch below the radiator cap opening.  
  • Leave the engine running for a while, and you can also rev it gently. If the coolant level doesn’t drop, close the radiator cap.  
  • Turn off your engine, let it cool down, and check the coolant level again. If there is a drop, add more coolant.  
How to replace a thermostat housing in a Jeep wrangler?


Engine cooling is among the factors determining your engine’s durability. The thermostat plays a huge role in regulating engine temperatures. Failure to ignore signs of a faulty thermostat and you might find yourself with a broken-down engine due to overheating damages the engine’s internals.

When filling up the radiator with a new coolant, ensure you get the recommended type and viscosity for your engine, as different wrangler engines have different coolant recommendations.