On-Vehicle Inspection

WARNING: This page is about a different car, the 2007 Toyota Tacoma. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT COOLING SYSTEM FOR LEAKAGE
CAUTION: To avoid the danger of being burned, do not remove the radiator cap while the engine and radiator are still hot. Fluid and steam could be blown out under pressure.
1. Fill the radiator with coolant and attach a radiator cap tester.
2. Warm up the engine.
3. Pump it up to 118 kPa (1.2 kgf/cm² , 17.1 psi) and check that the pressure does not drop.
  HINT:
  
  If the pressure drops, check the hose, radiator and water pump for leakage. If no external leakage is found, check the heater core, cylinder block and cylinder head.
  
  Fig 1: Inspecting Cooling System For Leakage
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
CHECK ENGINE COOLANT LEVEL AT RESERVOIR
1. Check that the coolant level in the reservoir tank is between the FULL and LOW lines when the engine is cold.
  If low, check for leakage and add Toyota Super Long Life Coolant or similar high quality ethylene glycol based non-silicate, non-amine, non-nitrite, and non-borate coolant with long-life hybrid organic acid technology up to the FULL line.
CHECK ENGINE COOLANT QUALITY
1. Remove the radiator cap.
  CAUTION: To avoid the danger of being burned, do not remove the radiator cap while the engine and radiator are still hot. Fluid and steam could be blown out under pressure.
2. Check that there are no excessive deposits of rust or scale around the radiator cap or radiator filler hole.
  If excessively dirty, replace the coolant.
3. Attach the radiator cap.