Engine Cooling System: Diagnosis Toyota Sequoia I

INSPECTION

1. Check engine coolant level at radiator reservoir . The engine coolant level should be between the "LOW" and "FULL" lines at normal temperature (20°C(68°F)). If low, check for leaks and add "TOYOTA Long Life Coolant" or equivalent up to the "FULL" line.
2. Check engine coolant quality . WARNING: To avoid the danger of being burned, do not remove the radiator cap while the engine and radiator are still hot, as fluid and steam can be blown out under pressure. Remove the radiator cap. There should not be any excessive deposits of rust or scale around the radiator cap or radiator filler hole, and the coolant should be free from oil. If excessively dirty, clean the coolant passages and replace the coolant. Reinstall the radiator cap.

Scheme 1

1. Remove engine under cover.
2. Drain engine coolant: WARNING: To avoid the danger of being burned, do not remove the radiator cap while the engine and radiator are still hot, as fluid and steam can be blown out under pressure. Remove the radiator cap. Remove the 3 drain plugs on the engine and radiator, and drain the coolant. (Scheme 1) Close the 3 drain plugs. Torque: 12.7 N.m (130 kgf.cm, 9 ft.lbf) for engine
3. Refill with engine coolant: Slowly fill the system with coolant. Use of improper coolants may damage engine cooling system. Use "TOYOTA Long Life Coolant" or equivalent and mix it with plain water according to the manufacturer'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 ethylene- glycol is recommended, but not more than 70%. NOTE: Do not use an alcohol type coolant or plain water alone. The coolant should be mixed with plain water (preferably demineralized water or distilled water). Capacity: 11.6 liters (12.3 US qts, 10.2 Imp. qts) Install the radiator cap. Bleed the cooling system. Start the engine, and open the heater water valve. Maintain the engine speed at 2,000 - 2,500 rpm, and warm up the engine. Stop the engine, and wait until the engine coolant cools down. Refill coolant into the reservoir until it is "FULL".
4. Check for engine coolant leaks.
5. Check engine coolant specific gravity correctly.
6. Reinstall engine under cover.

INSPECT THERMOSTAT

Note. The thermostat is numbered with the valve opening temperature. (Scheme 2)

Scheme 2

Scheme 3

Scheme 4

1. Immerse the thermostat in water and gradually heat the water. (Scheme 3)
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. (Scheme 4) Valve lift: 10 mm (0.39 in.) 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.

INSPECT FINS FOR BLOCKAGE

Note. If the distance between the steam cleaner and the core is too close, there is a possibility of damaging the fin, so keep the following injection distance. See STEAM CLEANER TO CORE DISTANCE . If the fins are bent, straighten them with a screwdriver or pliers. Never apply water directly onto the electronic components.

If fins are clogged, wash them with water or a steam cleaner and dry with compressed air. (Scheme 5)

STEAM CLEANER TO CORE DISTANCE

Scheme 5

Scheme 6

1. Remove radiator cap.
2. Inspect radiator cap. NOTE: Push the pump at a constant speed. 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) If air is not coming from the vacuum valve, replace the radiator cap. NOTE: This pump speed is for the first pump only (in order to close the vacuum valve). After this, the pump speed can be reduced. Use the tester's maximum reading as the opening pressure. If the opening pressure is less than minimum, replace the radiator cap. Pump the radiator cap tester, and measure the relief valve opening pressure. Pump speed: 1 push within 1 second For opening pressure, see «Radiator Cap Opening Pressure»(ref-170116-S06669976862005010300000). Radiator Cap Opening Pressure Application Specification Standard 74 - 103 kPa (0.75 - 1.05 kgf/cm 2, 10.7 - 14.9 psi) Minimum 59 kPa (0.6 kgf/cm 2, 8.6 psi)
3. Inspect cooling system for leaks: Fill the radiator with coolant and attach a radiator cap tester. see scheme 19 Warm up the engine. 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.