Engine Cooling System: Diagnosis Toyota MR2 W30

INSPECTION

Note. Check the coolant level when the engine is cold.

1. Check Engine Coolant Level At Reservoir The engine coolant level should be between the LOW and FULL line. If low, check for leaks and add "Toyota Long Life Coolant" or equivalent up to the "FULL" line.
2. Check Engine Coolant Quality Remove the reservoir cap. CAUTION: To avoid the danger of being burned, do not remove the reservoir the cap while the engine and radiator are still hot, as fluid and steam can be blown out under pressure. There should not be any excessive deposits of rust or scale around the reservoir cap or reservoir filler hole, and the coolant should be free from oil. If excessively dirty, replace the coolant. Reinstall the reservoir cap.

Inspect Water Pump

Note. Be sure to do checking when the engine coolant is charged.

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1. Remove the drive belt. See «REMOVAL»(ref-173147-S25244969412005031000000) .
2. Turn the pulley, and check that the water pump bearing moves smoothly and quietly. If necessary, replace the water pump.
3. Reinstall the drive belt «INSTALLATION»(ref-173147-S37754241662005031000000) .

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1. Drain Engine Coolant . See 1 under INSPECTION.
2. Remove Drive Belt . See «REMOVAL»(ref-173147-S25244969412005031000000) .
3. Remove Water Pump Remove the 6 bolts, water pump and gasket. Clean up the engine coolant from the water chamber room. NOTE: Do not remove the RH engine mounting bracket and generator when the water pump alone is replaced.

Note. Never rotate the pulley in a condition with a single unit of the water pump.

Visually check the drain hole for coolant leakage. If leakage is found, replace the water pump.

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1. Install Water Pump Place a new O-ring on the timing chain cover. Install the water pump with the 6 bolts. Torque: Bolt A: 9 N.m (92 kgf.cm, 80 in.lbf) Bolt B: 11 N.m (113 kgf.cm, 8 ft.lbf) NOTE: Each bolt length is indicated in the illustration.
2. Install Drive Belt . See «INSTALLATION»(ref-173147-S37754241662005031000000) .
3. Fill With Engine Coolant . See 2 under REPLACEMENT.
4. Start Engine And Check For Leak
5. Recheck Engine Coolant Level

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Inspect Thermostat

Note. The thermostat is numbered with the valve opening temperature.

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1. Immerse the thermostat in water and gradually heat the water.
2. Check the valve opening temperature. Valve opening temperature: 80-84°C (176 - 183.2°F) If the valve opening temperature is not as specified, replace the thermostat.
3. Check the valve lift. Valve lift: 10 mm (0.39 in.) or more at 90°C (194°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.

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1. Place Thermostat In Cylinder Block Install a new gasket to the thermostat. Install the thermostat with the jiggle valve upward. NOTE: The jiggle valve may be set within 10° of either side of the prescribed position.
2. Install Water Inlet Install the water inlet with the 2 nuts. Torque: 9 N.m (92 kgf.cm, 80 in.lbf)
3. Install Front Engine Under Cover
4. Install Generator And Drive Belt . See «INSTALLATION»(ref-173147-S37754241662005031000000) .
5. Fill With Engine Coolant . See 2 under REPLACEMENT.
6. Start Engine And Check For Leak
7. Recheck Engine Coolant Level

Inspect Lock Plate For Damage

Note. If the sides of the lock plate groove are deformed, reassembly of the tank will be impossible. Therefore, first correct any deformation with pliers or similar object. Water leakage will result if the bottom of the lock plate groove is damaged. NOTE: The radiator can only be recaulked 2 times. After the 2nd time, the radiator core must be replaced.

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1. Install New O-Rings And Tanks After checking that there are no foreign objects in the lock plate groove, install the new O-ring without twisting it. NOTE: When cleaning the lock plate groove, lightly rub it with sand paper without scratching it. Install the tank without damaging the O-ring. Tap the lock plate with a soft-faced hammer so that there is no gap between it and the tank.
2. Assemble SST SST 09230-01010, 09231-14010 Install the punch assembly to the overhaul handle, inserting it in the hole in part "A" as shown. While gripping the handle, adjust the stopper bolt so that dimension "B" is as shown. Dimension: 8.4 mm (0.331 in.)
3. Caulk Lock Plate Lightly press SST against the lock plate in the order shown in the illustration. After repeating this a few times, fully caulk the lock plate by squeezing the handle until stopped by the stopped plate. SST 09230-01010 NOTE: Do not stake the areas protruding around the pipes, brackets or tank rids. The points shown cannot be staked with SST. Use wrap vinyl tape around the tip of a pair or similar object and be careful not to damage the core plates. Check the lock plate height (H) after completing the caulking. Plate height (H): 7.4 - 7.8 mm (0.2913 - 0.3071 in.) If not within the specified height, adjust the stopper bolt of the handle again and caulk again.
4. Install Drain Plug Install a new O-ring to the drain plug. Install the drain plug.
5. Inspect For Water Leaks Tighten the drain plug. Install the engine coolant reservoir. Plug the inlet and outlet pipes of the radiator with SST. SST 09230-01010 Using a radiator cap tester, apply pressure to the radiator. Test pressure: 177 kPa (1.8 kgf/cm 2 , 26 psi) Submerge the radiator in water. Inspect for leaks. NOTE: On radiators with resin tanks, there is a clearance between the tank and lock plate where a minute amount of air will remain, giving the appearance of an air leak when the radiator is submerged in water, therefore, before doing the water leak test, first swish the radiator around in the water until all bubbles disappear.

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1. Install Electric Cooling Fan To Radiator Install the electric cooling fan with the 2 bolts. Torque: 5 N.m (51 kgf.cm, 44 in.lbf)
2. Install Radiator Assembly Install the 2 radiator lower support bushings. Place the radiator assembly to the body. Install the 2 radiator upper supports with the 4bolts. Torque: 12.5 N.m (128 kgf.cm, 9 ft.lbf) Connect the 2 radiator hoses. Connect the 2 electric cooling fan connectors. Install the 2 spear wheel carrier extensions with the 2 bolts and 2 nuts. Torque: 8 N.m (82 kgf.cm, 70 in.lbf)
3. Fill With Engine Coolant . See 2 under REMOVAL.
4. Install Luggage Compartment Trim Box Cover And Tool Box
5. Start Engine And Check For Leak
6. Recheck Engine Coolant Level

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1. Check Cooling Fan Operation With Low Temperature (Below 83°C (181°F)) Turn the ignition switch ON. Check that the cooling fan stops. If not, check the cooling fan relay and ECT sensor, and check for separated connector or severed wire between the cooling fan relay and ECT sensor. Disconnect the ECT sensor connector. Check that the cooling fan rotates. If not, check the fuses, cooling fan relay, ECM and cooling fan, and check for a short circuit between the cooling fan relay and ECT sensor. Reconnect the ECT sensor connector.
2. Check Cooling Fan Operation With High Temperature (Above 93°C (199°F)) Start the engine, and raise coolant temperature to above 93°C (199°F). NOTE: Coolant temperature is the detected value by the ECT sensor on the water outlet. Check that the cooling fan rotates. If not, replace the ECT sensor.
3. Inspect Cooling Fans Disconnect the cooling fan connector. Connect battery and ammeter to the connector. Check that the cooling fan rotates smoothly, and check the reading on the ammeter. Standard amperage: 5.7 - 7.7 A Reconnect the cooling fan connector.
4. Inspect ECT Sensor . See «ENGINE COOLANT TEMPERATURE SENSOR»(ref-133221-S39622789122002021900000) .
5. Inspect ECM Check the voltage between ECM terminals FAN and E1. See «PIN VOLTAGE CHARTS»(ref-133223-S14204756582002021900000) .

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1. Remove Tool Box And Luggage Compartment Trim Box Cover
2. Remove Electric Cooling Fan Disconnect the 2 electric cooling fan connectors. Remove the 2 bolts, 2 nuts and 2 spear wheel carrier extensions. Remove the 2 bolts and electric cooling fan.

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1. Remove Fans Remove the nut and fan.
2. Remove Fan Motors Disconnect the wire and connector holder from the fan shroud. Remove the 3 screws and fan motor.

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1. Install Fan Motors Install the fan motor with the 3 screws. Torque: 2.55 N.m (26 kgf.cm, 23 in.lbf) Install the wire and connector holder to the fan shroud.
2. Install Fans Install the fan with the nut. Torque: 6.18 N.m (63 kgf.cm, 55 in.lbf)

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1. Install Electric Cooling Fan Install the electric cooling fan with the 2 bolts. Torque: 5 N.m (51 kgf.cm, 44 in.lbf) Install the 2 spear wheel carrier extensions with the 2 bolts and 2 nuts. Torque: 8 N.m (82 kgf.cm, 70 in.lbf) Connect the 2 electric cooling fan connectors.
2. Install Luggage Compartment Trim Box Cover And Tool Box

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1. Inspect No. 1 Cooling Fan Relay Remove the R/B No. 4 cover. Remove the No. 1 cooling fan relay. (Marking: FAN No. 1) Inspect the No. 1 cooling fan relay continuity. Using an ohmmeter, check that there is continuity between terminals 1 and 2. If there is no continuity, replace the relay. Check that there is no continuity between terminals 3 and 5. If there is continuity, replace the relay. Inspect the No. 1 cooling fan relay operation. Apply battery positive voltage to terminals 1 and 2. Using an ohmmeter, check that there is continuity between terminals 3 and 5. If there is no continuity, replace the relay. Reinstall the No. 1 cooling fan relay. Reinstall the R/B No. 4 cover.
2. Inspect No. 2 And No. 3 Cooling Fan Relays . See «COOLING FAN RELAY»(ref-138690-S04365877302005031000000) .