Clean the gasket surfaces.
Do not let any debris fall into the thermostat
cavity when cleaning gasket surfaces.
Always use the correct thermostat and never
operate the engine without a thermostat. An
incorrect thermostat can cause the engine to
overheat or run too cold. The engine will
overheat if operated without a thermostat
because the coolant flows back to the inlet of
the water pump instead of through the
radiator for cooling.