Overheating after thermostat change

2JZINTHETRASH

MEMBER
2000 LEXUS GS 300
3.0L
6 CYL
2WD
AUTOMATIC
135,000 MILES

I just replaced the thermostat because it was stuck open and throwing a CEL, after replacing it the car starts to overheat after I drive it maybe five to ten minutes but once I park it stops gaining temperature and balances out where it is at. I thought there was just air in the system so I burped it four times and now a five, have not driven it yet so do not know if it solves the problem. But let’s just assume I did not and it starts to overheat again, the radiator is full and the overflow tank is full enough that it is draining the overflow. It never overheats while idling before driving. Thermostat and water pump both good, cooling fans kick on, there is enough coolant. I just cannot seem to figure out if I just have a little bit of air in the line or if there is something else. Thanks.

1 Reply

JACOBANDNICKOLAS

MECHANIC
108,192 POSTS

Hi and thanks for using 2CarPros. Com. It sounds like you have everything working the way it should. My only concern is if the thermostat was installed correctly. Here are specific directions for your vehicle. Scan through them to ensure directions were followed. If they were and you still have the issue, chances are you have a sticky new thermostat. These directions also include how to check the part.

2000 Lexus GS 300 L6-3.0L (2JZ-GE)
Vehicle � Engine, Cooling and Exhaust � Cooling System � Thermostat � Service and Repair
SERVICE AND REPAIR
REMOVAL
HINT:
Removal of the thermostat would have an adverse effect, causing a lowering of cooling efficiency. Do not remove the thermostat, even if the engine tends to overheat.
DRAIN ENGINE COOLANT
DISCONNECT WATER INLET FROM WATER PUMP, AND REMOVE THERMOSTAT
a) Remove the 2 nuts holding the water inlet to the water pump, and disconnect the water inlet from the water pump.
B) Remove the thermostat.
C) Remove the gasket from the thermostat.
INSPECTION
INSPECT THERMOSTAT
HINT: The thermostat is numbered with the valve opening temperature.
A) Immerse the thermostat in water and gradually heat the water.
B) Check the valve opening temperature.
Valve opening temperature: 80 - 84°C (176 - 183°F)
If the valve lift is not as specified, replace the thermostat.
C) Check the valve lift.
Valve lift: 8.5 mm (0.335 inch) or more at 95°C (203°F)
If the valve lift is not as specified, replace the thermostat.
D) Check that the valve is fully closed when the thermostat is at low temperatures (below 40°C (104°F) ).
If not closed, replace the thermostat.
INSTALLATION
PLACE THERMOSTAT IN WATER INLET
a) Install a new gasket to the thermostat.
B) Align the jiggle valve of the thermostat with the protrusion of the water inlet.
INSTALL WATER INLET Install the water inlet with the 2 nuts.
Torque: 9.0 Nm (90 kgf-cm, 80 inch lbs.)
FILL WITH ENGINE COOLANT
START ENGINE AND CHECK FOR COOLANT LEAKS

Let me know if this helps or if you have other questions.

Take care,
Joe

Images (Click to make bigger)