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How to Change a Thermostat in a 2001 Toyota Tacoma V6

by Rex Molder

The 2001 Toyota Tacoma's cooling system uses a thermostat that attaches to the engine via the lower radiator hose. When the engine is cold, the thermostat remains closed to help the truck quickly reach operating temperature. Once warm, the thermostat opens, allowing coolant to flow through the engine. A thermostat that is malfunctioning can cause the vehicle to take too long to warm up or can cause the vehicle to overheat; in either case, it should be replaced.

Drain Radiator

Wait for the engine to cool down to prevent burns caused by hot coolant. Open the hood and use a socket wrench to disconnect the negative battery cable.

Open the radiator cap. Place a container beneath the radiator drain plug located at the front passenger's side of the radiator. To prevent spillage, attach a piece of 3/8-inch tubing to the drain plug.

Turn the drain plug counterclockwise to open it. The valve may be tight require the use of pliers to open it. Open the radiator cap to allow air to enter the system, making the coolant drain faster.

Move the container underneath the engine block drain plug, just below the oil filter. If coolant doesn't drain when you remove the plug, insert a screwdriver into the hole to break the seal.

Close the radiator drain plug and replace the engine block drain plug when the coolant has completely drained.

Replace Thermostat

Locate thermostat housing by following the lower radiator hose to where it connects to the engine.

Unscrew the two nuts that hold the housing to the engine with a socket wrench. Pull the housing off the engine. The housing will likely be stuck to the engine so you will need to gently tap it with a rubber mallet to break it free. Once you detach the housing, some coolant will spill so be prepared for that with a drip pan.

Remove the thermostat and ensure the attaching surface of the thermostat housing is clean. If traces of the old gasket are stuck to the housing, use a flat head screwdriver to remove the residue.

Insert the new thermostat into the engine with the spring facing towards the engine. Ensure that the small pin attached to the outer rim of the thermostat is positioned at the top.

Reattach the housing and replace the two nuts.

Replace the coolant. Fill the radiator then fill the overflow reservoir to the full mark. If the drained coolant is in good condition, you can reuse it.

Reconnect the negative battery cable. Start the vehicle and let it run with the radiator cap off until the thermostat opens. Turn on the truck's heater and set it to the hottest temperature. You can tell when the thermostat opens by touching the top radiator hose. Once it feels hot to the touch, the thermostat is open, and coolant is flowing.

Turn off the engine and add coolant to the radiator until the fluid reaches the rim of the radiator filler neck. Squeeze the top radiator hose to push air out of the system and add more coolant if necessary. Replace the radiator cap.

Start the engine and let it run several minutes while you check for leaks.

Tips

  • If you have a torque wrench, tighten the thermostat housing nuts to 168 inch-pounds. If you don't have a torque wrench, tighten the bolts until they are snug but do not apply excessive pressure to avoid stripping the bolt threads.
  • There is no need to detach the lower radiator hose from the thermostat housing.

Warning

  • Antifreeze is extremely toxic. Clean up any spills and place the container where pets cannot drink it.

Items you will need

References

About the Author

Rex Molder began writing professionally in 1999 and specializes in automotive, technology and travel articles. His articles have appeared at iPad- and SEO-related websites. Rex holds a Bachelor of Arts in Asian studies from University of North Carolina-Chapel Hill.

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