Introduced on 1991, the Renault Clio has a reputation of being a great vehicle for adding bolt-on horsepower products to get extra pep from the engine. Doing so can cause the cooling system to fail; when it does, the engine can warp, rendering it useless. You can avoid this by replacing the thermostat with one that will not allow your engine to overheat.
Remove the radiator hose from the thermostat cover by loosening the radiator hose band clamp with a screwdriver. Drain the fluid from the hose into a small bucket. Once drained, push the hose to the side so the thermostat cover can be easily accessed.
Remove the bolts that hold the thermostat cover onto the intake manifold with an adjustable wrench and set the bolts off to the side. They will be reused when the cover is bolted back into place. Pull the thermostat cover off the Renault Clio and set it off to the side.
Pull the thermostat out of the intake manifold, then pull the thermostat cover gasket off the intake manifold. Throw both items away. They will not be used again.
Set a new thermostat cover gasket onto the intake manifold, then set the new thermostat in place. Make sure the correct end is up; it should be marked to show you which end should stick out of the Clio's engine.
Bolt the thermostat cover into place using the original bolts. The cover should not be over-tightened--if it is, the thermostat cover can crack because it is made out of "cast" metal.
Place the radiator hose back onto the thermostat cover and tighten down the band clamp with a screwdriver. The clamp should be tight to prevent leaks.
Replace the fluid that was drained from the hose by filling the radiator with fresh fluid via the radiator filler cap.