To remove and install the thermostat, with the engine cold remove the radiator cap and then drain the cooling system. For the 1.5-litre and 2.4-litre models disconnect the PCV hose, loosen the hose retaining clamps and pull off the air inlet hose; for the 2.4-litre, remove the air cleaner housing and air intake duct. Next, the hose clamp should be released and the upper radiator hose disconnected from the thermostat cover. The retaining bolts should be removed and the thermostat cover removed. Take note of the installed position, then remove the thermostat. In the case of the 1.8 and 2.0 litre models, release the hose clamp and take off the lower radiator hose from the thermostat cover. Remove the retaining bolts and the thermostat cover. Remove the thermostat, noting its installed position. A visual check can sometimes indicate whether the thermostat is still viable or not; for example, a thermostat with its valve fully opened after removal from a cold engine is obviously faulty and should therefore be replaced. Earlier, we removed Stage 1 to finally Stage 1, retaining bolts, and pay attention not to damage other components. The rest of the components to be removed varies with the engine. After the removal, we clean the mating surfaces of the thermostat cover and housing are clean and flat. The thermostat is installed in the same position as noted with the jiggle valve facing up. Finally, after tightening the retaining bolts to specification, the cooling system is refilled. To test the thermostat, check that the valve is fully closed when cold and then suspend and immerse with a reliable thermometer in a container of cold water (they should not touch the container). Heat the water gradually, observing thermometer reading, the valve should start to open at 82 ± 1.5°C. In order to verify that the thermostat valve opens at least 8.5 mm, heat the water to 95°C. If the en- opening temperature of the thermostat and valve lift are out of specification, the thermostat must be replaced. Check that the thermostat is fully closed when cooled below the valve opening temperature; if not, replace the thermostat.