How to Change a Radiator Thermostat How to Change a Radiator Thermostat

What You'll Need
Screwdriver
Work gloves
Wrench
New thermostat
New gasket
Gasket scraper
Gasket sealer
Old towel or rag
Old container

A radiator thermostat is a heat sensitive valve which controls the flow of coolant from the radiator to the engine. The valve opens and releases the coolant once the engine has warmed to the right temperature. It plays a key role in the overall performance of your car and is vital that you keep your car's radiator thermostat in good working order. Changing a radiator thermostat yourself is a fairly simple task.

Step 1 - Draining the Cooling System

Remember that you should only begin working on your car once the engine has cooled. A few hours after use is usually the safest approach. Put on your work gloves before starting. After removing the radiator cap, drain the radiator of coolant until the fluid falls below the thermostat. This can be done by using a wrench to open the drain valve which you will find at the bottom of the radiator. Drained fluid can be run into an old container and disposed of safely.

Step 2 -Exposing the Thermostat

Follow the radiator's upper hose from the radiator to the engine. This hose connects to the engine via the thermostat housing.
Using a Flathead screwdriver, loosen the screw on the hose, remove it from the thermostat housing and put aside.
You should expect coolant to leak out when you do this so have an old towel or rag handy.

Step 3 - Removing the Thermostat

Use your wrench to remove the bolts on either side of the thermostat housing. This area may be hard to reach due to the location of the thermostat in your vehicle. You may need to use a wrench extension which usually come in lengths of 3, 6, or 12 inches. Once unbolted, remove the thermostat housing from the engine to reveal the thermostat. Take note of the position of the faulty thermostat within the engine before lifting it, along with the gasket, out of the engine.

Step 4 - Cleaning

Using your gasket scraper, clean the thermostat housing and the area where the housing meets the engine. Scrape the surfaces so that they are free of any remnants of the old gasket, along with any other foreign fragments.

Step 5 - Inserting the New Thermostat

Place the new thermostat in the engine. Make sure that you position it in the exact same place that the old one was otherwise it may fail to work. Coat both sides of the new thermostat gasket with gasket sealer. Place one side of the gasket against the thermostat housing and push the gasket into position. Now, place the housing over the thermostat. Bolt the thermostat housing down to the engine and tighten with your wrench.

Step 6 - Replacing the Upper Hose

Re-attach the upper radiator hose to the thermostat housing and using your screwdriver, screw the hose back onto the housing.

Step 7 -  Refilling the Radiator

Use your wrench to close the valve on the radiator before filling it with new coolant. Replace the radiator cap and turn the engine on. Then, switch off the engine and check the fluid level.

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