how to replace thermostate on 1999 Lexus RX300

car overheating and then suddenly cools, sounds verymuch like a bad thermostste

by in Escondido, CA on February 12, 2011
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1 answer
ANSWER by , February 12, 2011
Here is how to do it. If you need the supporting graphics you need to post an e-mail and I can send the whole thing to you. 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. 1. DRAIN ENGINE COOLANT 2. REMOVE AIR CLEANER CAP AND AIR CLEANER CASE 3. DISCONNECT NO.2 ECT SWITCH CONNECTOR 4. DISCONNECT ENGINE WIRE PROTECTOR FROM WATER INLET AND RH CYLINDER HEAD Remove the nut and disconnect the clamp, and disconnect the engine wire protector from the water inlet and cylinder head. 5. DISCONNECT WATER INLET PIPE FROM WATER INLET AND LH CYLINDER HEAD 1. Remove the bolt, and disconnect the inlet pipe from the water inlet. 2. Remove the O-ring from the inlet pipe. 6. REMOVE WATER INLET AND THERMOSTAT 1. Remove the 3 nuts, water inlet and thermostat. 2. Remove the gasket from the thermostat. INSPECTION Inspect Thermostat HINT: The thermostat is numbered with the valve opening temperature. 1. Immerse the thermostat in water and gradually heat the water. 2. Check the valve opening temperature. Valve opening temperature: 80 - 84°C (176 - 183°F) If the valve opening temperature is not as specified, replace the thermostat. 3. Check the valve lift. Valve lift: 10.0 mm (0.394 inch) or more at 95°C (203°F) If the valve lift is not as specified, replace the thermostat. 4. 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 1. PLACE THERMOSTAT IN WATER PUMP 1. Install a new gasket on to the thermostat. 2. Align the thermostat jiggle valve with the upper stud bolt, and insert the thermostat in the water inlet housing. HINT: The jiggle valve may be set within 15° of either side of the prescribed position. 2. INSTALL WATER INLET Install the water inlet with the 3 nuts. Torque: 8 Nm (80 kgf-cm, 69 inch lbs.) 3. INSTALL WATER INLET PIPE 1. Install a new O-ring to the water inlet pipe. 2. Apply soapy water to the O-ring. 3. Connect the water inlet pipe to the water inlet. 4. Install the bolt holding the water inlet pipe to the cylinder head. Torque: 19.5 Nm (200 kgf-cm, 14 ft. lbs.) 4. INSTALL ENGINE WIRE PROTECTOR 5. CONNECT ECT SWITCH CONNECTOR 6. REINSTALL AIR CLEANER CAP AND AIR CLEANER CASE 7. FILL WITH ENGINE COOLANT 8. START ENGINE AND CHECK FOR LEAKS 9. RECHECK ENGINE COOLANT LEVEL Zee