Lexus Thermostat Related Questions

Where is the Lexus thermostat located? Do you need to know if the thermostat needs replaced? The thermostat blocks the flow of coolant to the radiator until the engine has warmed up. It opens up once the engine reaches its operating temperature. Thermostats can fail to open preventing the vehicle from getting any heat or they can fail to close causing the motor to overheat. Not being aware of the engine’s regular operating temperature or how to handle the problems that occur could lead to questions that need answered in a timely manner. Read below where Experts have answered Lexus owner’s questions regarding the thermostat and its related problems.

Where is the thermostat located in a 1996 Lexus ES300?

The thermostat is located behind the tube that runs from the radiator hose that comes up on the driver side of the engine.

How can the thermostat be accessed in a 1999 Lexus 300?

The battery and the air cleaner assembly will need to be removed to access the thermostat housing.

Why is the port on top of the thermostat the best way to fill coolant in a 1993 Lexus LS400?

In order to avoid air pockets, it is best to fill coolant with a funnel using the port on top of the thermostat.

How to check if a faulty thermostat is causing a Lexus LS400 to overheat?

The vehicle could be run without the thermostat. If it continues to heat after removing the thermostat, it proves that the thermostat is not faulty.

Can a defective thermostat cause an ‘overdrive’ to shift out in a 1994 ES300?

The overdrive shifting out is usually traced to a thermostat issue. The overdrive is prevented from engaging when it is less than 177 degrees F. This built in temperature cannot be modified. If the coolant goes below 177 degrees (like if the thermostat sticks open), the ‘overdrive’ will disengage. If the temperature gauge shows lower than normal, it indicates that the thermostat may be 'open' too long. The thermostat will need to be replaced.

What is the procedure to replace the thermostat in a Lexus?

The first step would be to drain the coolant into a suitable container and then do the following:

1. Disconnect the negative and positive battery cables and remove the battery.
2. Remove the air cleaner assembly, as follows:
   • Disconnect the mass air flow (MAF) meter connector and wire clamp.
   • Disconnect the VSV connector for the canister closed valve (CCV) and air hose.
   • Disconnect the three vacuum hoses and loosen the hose clamp.
   • Remove the air cleaner cap.
   • Remove the air filter.
   • Remove the bolts and air cleaner case. 
   • Disconnect the outlet radiator hose.
3. Remove the bolt and water inlet pipe.
4. Remove the 3 bolts and water inlet pipe.
5. Remove the thermostat assembly.
6. Remove and discard the gasket and thoroughly clean the gasket mating surface.

To install:

1. Position a new gasket to the thermostat.
2. Align the thermostat jiggle valve with the upper stud bolt and insert the thermostat in the water inlet housing.  (The jiggle valve can be placed within 15° of either side of the described position.
3. Install the water inlet and tighten the bolt to 71 inch lbs. (8 Nm). Install the water inlet pipe, as follows:
   • Install a new O-ring to the water inlet pipe.
   • Apply soapy water to the O-ring.
   • Connect the water inlet pipe to the water inlet.
   • Install the bolt holding the water inlet pipe to the cylinder head and tighten to 15 ft. lbs. (20 Nm).
4. Install the air cleaner assembly in the reverse of the removal procedure. Tighten the case retainers to 44 inch lbs. (5 Nm).
5. Install the battery. Connect the positive, then the negative battery cables.
6. Fill the engine with the proper type and amount of engine coolant.
7. Start the engine and check for coolant leaks. Recheck the coolant level and add, as necessary.

The Lexus thermostat system is an important component as it tells you how well the temperature is being regulated. When it malfunctions it can cause major engine damage if not attended to as soon as possible. When owners need additional assistance with the maintenance and repair of a thermostat contact an Expert. Verified mechanical Experts are readily available to assist you with all your needs.