Page 468 of 1111
CO0A5±01
P 1111 7
ProtrusionJiggle Valve
± COOLING (2JZ±GE)THERMOSTAT
CO±13
1551 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSTALLATION
1. 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.
2. INSTALL WATER INLET
Install the water inlet with the 2 nuts.
Torque: 9.0 N´m (90 kgf´cm, 80 in.´lbf)
3. FILL WITH ENGINE COOLANT
4. START ENGINE AND CHECK FOR COOLANT LEAKS
Page 470 of 1111

CO0A7±01
CO1242
Radiator Cap Tester
Radiator Cap
30° or More
B01882
Radiator Cap Tester
± COOLING (2JZ±GE)RADIATOR
CO±15
1553 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
ON±VEHICLE INSPECTION
1. REMOVE RADIATOR CAP
Remove the radiator cap from the radiator.
CAUTION:
To avoid the danger of being burned, do not remove the ra-
diator cap while the engine and radiator are still hot, as fluid
and steam can be blown out under pressure.
2. INSPECT RADIATOR CAP
NOTICE:
If the radiator cap has contaminations, always rinse
it with water.
Before using a radiator cap tester, wet the relief valve
and pressure valve with engine coolant or water.
When performing steps (a) and (b) below, keep the
tester at an angle of over 30° above the horizontal.
(a) Using a radiator cap tester, slowly pump the tester and
check that air is coming from the vacuum valve.
Pump speed: 1 push/(3 seconds or more)
NOTICE:
Push the pump at a constant speed.
If air is not coming from the vacuum valve, replace the radiator
cap.
(b) Pump the radiator cap tester, and measure the relief valve
opening pressure.
Pump speed: 1 push within 1 second
NOTICE:
This pump speed is for the first pump only (in order to close
the vacuum valve). After this, the pump speed can be re-
duced.
Standard opening pressure:
93 ± 123 kPa (0.95 ± 1.25 kgf/cm
2, 13.5 ± 17.8 psi)
Minimum opening pressure:
78 kPa (0.8 kgf/cm
2, 11.4 psi)
HINT:
Use the tester's maximum reading as the opening pressure.
If the opening pressure is less than minimum, replace the radia-
tor cap.
3. INSPECT COOLING SYSTEM FOR LEAKS
(a) Fill the radiator with coolant and attach a radiator cap tes-
ter.
(b) Warm up the engine.
(c) Pump it to 118 kPa (1.2 kgf/cm
2, 17.1 psi), and check that
the pressure does not drop.
If the pressure drops, check the hoses, radiator or water pump
for leaks. If no external leaks are found, check the heater core,
cylinder block and head.
4. REINSTALL RADIATOR CAP
Page 473 of 1111

CO0A9±03
B01881
CO±18
± COOLING (2JZ±GE)RADIATOR
1556 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
REMOVAL
1. REMOVE ENGINE UNDER COVER
2. DRAIN ENGINE COOLANT
3. REMOVE AIR CLEANER INLET
4. REMOVE AIR CLEANER AND MAF METER AS-
SEMBLY
5. REMOVE RADIATOR AND ELECTRIC COOLING FAN
ASSEMBLY
(a) Disconnect the upper radiator hose from the radiator.
(b) Disconnect the lower radiator hose from the radiator.
(c) Disconnect the ECM outlet duct from the ECM box.
(d) Disconnect the wire for electric cooling fan from the clamp
on the electric cooling fan.
(e) Disconnect the 2 electric cooling fan connectors.
(f) Disconnect the ECT switch connector for electric cooling
fan.
(g) Disconnect the 2 oil cooler hoses for A/T from the radiator.
(h) Remove the 2 nuts and 2 upper radiator supports.
(i) Lift out the radiator and cooling fan assembly.
(j) Remove the 2 lower radiator supports.
6. REMOVE ELECTRIC COOLING FAN FROM RADIA-
TOR
(a) Disconnect the radiator reservoir hose from the radiator.
(b) Remove the 6 bolts and electric cooling fan.
Page 475 of 1111

CO09X±03
Z07402
Drain Plug
Drain Plug
B01611
Drain Plug
Rubber
HoseConnect
CO±2
± COOLING (2JZ±GE)COOLANT
1540 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
REPLACEMENT
1. DRAIN ENGINE COOLANT
(a) Remove the radiator cap.
CAUTION:
To avoid the danger of being burned, do not remove the ra-
diator cap while the engine and radiator are still hot, as fluid
and steam can be blown out under pressure.
(b) Loosen the 2 drain plugs (for the engine and radiator),
and drain the coolant.
HINT:
To prevent the coolant from spraying over the cylinder block,
connect the rubber hose (inside diameter 6 ± 8 mm) in the mar-
ket to the union pipe under the drain plug.
(c) Close the drain plugs.
Torque: 30 N´m (300 kgf´cm, 22 ft´lbf) for engine
2. FILL ENGINE COOLANT
(a) Slowly fill the system with coolant.
Use of improper coolants may damage engine cool-
ing system.
Use ºToyota Long Life Coolantº or equivalent and
mix it with plain water according to the manufac-
ture's directions.
Use of the coolant which includes more than 50%
[freezing protection down to ±35°C (±31°F)] or 60%
[freezing protection down to ±50°C (±58°F)] of eth-
ylene ±glycol is recommended, but not more than
70%.
NOTICE:
Do not use an alcohol type coolant or plain water
alone.
The coolant should be mixed with plain water (prefer-
able demineralized water or distilled water).
Capacity (w/ Heater):
7.7 liters (8.1 US qts, 6.8 lmp. qts)
(b) Install the radiator cap.
(c) Start the engine, and bleed the cooling system.
(d) Refill the reservoir with coolant until it reaches the ºFULLº
line.
3. CHECK ENGINE COOLANT FOR LEAKS
4. CHECK ENGINE COOLANT SPECIFIC GRAVITY COR-
RECTLY
Page 479 of 1111

CO0AC±01
B01881
± COOLING (2JZ±GE)RADIATOR
CO±23
1561 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSTALLATION
1. INSTALL ELECTRIC COOLING FAN TO RADIATOR
(a) Install the electric cooling fan with the 6 bolts.
Torque: 5.0 N´m (50 kgf´cm, 44 in.´lbf)
(b) Connect the radiator reservoir hose to the radiator.
2. INSTALL RADIATOR AND ELECTRIC COOLING FAN
ASSEMBLY
(a) Install the 2 lower radiator supports to the radiator.
(b) Attach the 2 lower radiator supports on the radiator to the
body bracket.
(c) Install the radiator and electric cooling fan assembly with
the 2 upper radiator supports and 2 nuts.
Torque: 13.5 N´m (135 kgf´cm, 10 ft´lbf)
(d) Connect these parts:
Upper radiator hose to radiator
Lower radiator hose to radiator
ECM outlet duct to ECM box
Wire for electric cooling fan to clamp on electric
cooling fan
2 electric cooling fan connectors
ECT switch connector for electric cooling fan
2 oil cooler hoses for A/T to radiator
3. INSTALL AIR CLEANER AND MAF METER AS-
SEMBLY
4. INSTALL AIR CLEANER INLET
5. FILL WITH ENGINE COOLANT
6. START ENGINE AND CHECK FOR ENGINE COOLANT
AND A/T FLUID LEAKS
7. INSTALL ENGINE UNDER COVER
Page 480 of 1111

B01900
CO0AD±03
B00922
ECT
Switch
Connector
B02072
B02073
Ammeter
Battery(+)
(±)
CO±24
± COOLING (2JZ±GE)ELECTRIC COOLING FAN
1562 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
ELECTRIC COOLING FAN
ON±VEHICLE INSPECTION
1. CHECK COOLING FAN OPERATION WITH LOW
TEMPERATURE (Below 83°C (181°F))
(a) Turn the ignition switch ON.
(b) Check that the cooling fan stops.
If not, check the cooling fan relay and ECT switch, and check
for a separated connector or severed wire between the cooling
fan relay and ECT switch.
(c) Disconnect the ECT switch connector.
(d) Check that the cooling fan rotates.
If not, check the fuses, radiator fan main relay, cooling fan relay,
cooling fan, and check for a short circuit between the cooling
fan relay and ECT switch.
(e) Reconnect the ECT switch connector.
2. CHECK COOLING FAN OPERATION WITH HIGH
TEMPERATURE (Above 93°C (199°F))
(a) Start the engine, and raise coolant temperature to above
93°C (199°F).
HINT:
Coolant temperature is the detected value by the ECT switch
on the radiator lower tank.
(b) Check that the cooling fan rotates.
If not, replace the ECT switch.
3. INSPECT COOLING FANS
(a) Disconnect the cooling fan connector.
(b) Connect battery and ammeter to the cooling fan connec-
tor.
(c) Check that the cooling fan rotates smoothly, and check
the reading on the ammeter.
Standard amperage: 8.5 ± 11.5 A at 20°C (68°F)
(d) Reconnect the cooling fan connector.
Page 483 of 1111
CO0AF±03
B02071
± COOLING (2JZ±GE)ELECTRIC COOLING FAN
CO±27
1565 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
REMOVAL
1. DRAIN ENGINE COOLANT
2. REMOVE AIR CLEANER INLET
3. REMOVE AIR CLEANER AND MAF METER AS-
SEMBLY
4. REMOVE ELECTRIC COOLING FAN
(a) Disconnect the upper radiator hose from the radiator.
(b) Disconnect the ECM outlet duct from the ECM box.
(c) Disconnect the wire for electric cooling fan from the clamp
on the electric cooling fan.
(d) Disconnect the 2 electric cooling fan connector.
(e) Disconnect the radiator reservoir hose from the radiator.
(f) Remove the 6 bolts and electric cooling fan.
Page 488 of 1111
CO0AI±03
B02071
CO±30
± COOLING (2JZ±GE)ELECTRIC COOLING FAN
1568 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSTALLATION
1. INSTALL ELECTRIC COOLING FAN
(a) Install the electric cooling fan with the 6 bolts.
Torque: 5.0 N´m (50 kgf´cm, 44 in.´lbf)
(b) Connect the upper radiator hose to the radiator.
(c) Connect the ECM outlet duct to the ECM box.
(d) Connect the wire for electric cooling fan to clamp on the
electric cooling fan.
(e) Connect the 2 electric cooling fan connectors.
(f) Connect the radiator reservoir hose to the radiator.
2. INSTALL AIR CLEANER AND MAF METER AS-
SEMBLY
3. INSTALL AIR CLEANER INLET
4. FILL WITH ENGINE COOLANT
5. START ENGINE AND CHECK FOR COOLANT LEAKS