1. The thermostat on a 1993 Lexus LS 400 is located on the front of the engine, just below the upper radiator hose.
2. It is held in place by two 12mm bolts.
3. To remove the thermostat, first disconnect the negative battery cable.
4. Then, drain the coolant from the radiator.
5. Remove the two 12mm bolts holding the thermostat in place.
6. Lift the thermostat out of the housing, being careful not to spill any coolant.
7. Inspect the thermostat for damage or corrosion.
* If the thermostat is damaged or corroded, replace it with a new one.
8. Reinstall the thermostat in reverse order of removal.
* Make sure to put a new O-ring on the thermostat before installing it.
9. Fill the radiator with coolant and reconnect the negative battery cable.
10. Start the engine and let it run for a few minutes.
11. Check for leaks and make sure the thermostat is working properly.
