The 2003 Toyota Matrix is a popular sub-compact coupe that has helped to make Toyota a top-of-the-line foreign auto manufacturer. Due to their popularity there are several repair manuals available that can help you forgo taking the vehicle to a repair garage to have small things like the thermostat corrected. If you have a basic knowledge of engine repair and a few shop tools you can remove and replace that worn out thermostat with one that will properly regulate that Matrix engine.
Pull the radiator hose off of the thermostat housing by releasing the radiator hose retaining clip with a screwdriver and then pull the hose off of the housing. Shove a towel into the radiator hose to prevent getting radiator fluid on the engine.
Remove the two bolts that hold the thermostat housing onto the intake of the 2003 Toyota Matrix. With the bolts removed, lift the thermostat housing off of the intake.
Pull the thermostat out of the intake and then remove the thermostat gasket. The thermostat gasket may stick to the intake. If this happens you must scrape the gasket off with a scraper. If you need to scrape the gasket off you can avoid getting anything into the intake by filling the hole inside of the intake with a shop towel.
Place the new gasket onto the intake manifold and then place the new thermostat into the intake.
Place the thermostat housing back on top of the thermostat gasket and bolt it back into place. If the bolts are over tightened it can crack the bolt tabs on the housing.
Place the radiator hose back onto the thermostat housing and secure it with the retaining clip.
