1. Check coolant deaeration tank for contamination and correct fill level.
• If coolant level is low, do step 2.
• If coolant level is correct, do step 6.
• If coolant is contaminated with oil, go to “Lube Oil in Coolant” (page 122).
2. Inspect for coolant leaks. Check for external leaks from coolant hoses, radiator, heater core, engine, or cylinder head cup plugs. Check for coolant in oil.
• If any external leaks are found, repair and fill cooling system. Test again for over-temperature condition.
• If oil is contaminated with coolant, go to “Coolant in Lube Oil” (page 109) in this section.
• If no leaks are found, do step 3.
3. Fill cooling system to the maximum coolant level mark.
4. Start the engine.
5. Purge all air out of system by opening the coolant crossover pipe drain valve. Close the port when coolant appears.
6. Test again for over-temperature condition
• If the engine is not running over-temperature, do step 7.
• If the engine continues overheating, do step
7. Install radiator pressure tester with the appropriate adapter.
8. Pressurize the cooling system to 96 kPa (14 psi)
• If coolant is leaking externally, identify the leak and repair.
• If coolant is not leaking externally, but the pressure is dropping, see “Coolant Leak to Exhaust” (page 117) and “Coolant in Lube Oil” (page 109) in this section.
9. Inspect the condition of the following items: cooling fan blade, shroud, accessory drive belt,
accessory drive belt tensioner, cooling fan drive clutch, operation of electric or air fan, and radiator.
CAUTION: To avoid radiator damage, when using high pressure washer, be careful not to damage
radiator fins with wand.
• If vehicle is new or recently repaired, verify the correct part number for any component
related to the cooling system.
• If the radiator cooling fins are blocked due to a build-up of dirt or debris, use a power washer to clean blockage from radiator fins or any debris on the cooling fan and fan drive clutch.
• If no problems are identified, go to “Temperature Electrical System Test” (page 120) in this section.
