1991 Lexus LS400 Q&A
1991 Lexus LS400 Question: How do I know if I need to replace the thermostat on my car?
My cars water level is normal with no change, and I have not observed any leaks, but my car has stated to run warmer than normal. I turned on the heater to avoid it over-heating. I have not allowed it to go into the red on the temp gauge I just run the heater to keep it low. It doesn't matter what kind of driving I do, it now always warms quickly and I run the heater to keep it from getting too hot. - PricelessCJB
An auto repair shop would use a non contact temperature gun to measure the engine's running temperature to see if the running temperature is correct. The thermostat should open at approximately 195 degrees in your Lexus. Feel the top radiator hose, it will be cool to moderatly warm until the thermostat opens at which time the top and bottom hose at the radiator will both be warm. - patrick mannion
You'll have to pay a diagnostic fee to most shops since we pay our technicians to perform the work. It's better to know exactly what the vehicle needs rather than throw a dozen parts at it. With a vehicle your age I would expect you to need a thermostat, hoses and possibly a radiator. The plastic tanks become brittle over time and will fail at the worse possible moment. Have you already replaced your timing belt and water pump? - Hal...