When the engine's cooling system becomes contaminated, it should be flushed thoroughly to remove the contaminants before the engine is seriously damaged. One source of contamination that is damaging to the engine, if not corrected immediately, is a cracked oil gallery. With a cracked oil gallery, oil will be forced into the cooling system while the engine is operating, and when it is stopped, coolant will leak into the lubricating system. If mixed with oil in the crankcase, this antifreeze forms a varnish which quickly immobilizes moving engine parts.

To remove such contaminants from the engine, both the cooling system and the lubrication system must be thoroughly flushed after the engine is repaired.

Caution: In order to avoid personal injury, do not remove the cap or open the cooling system drains from a hot system. Allow the system to cool first.

If the engine has had a failure resulting in the contamination of the cooling system with lubricating oil, or a substance other than a recommended antifreeze has been added, the following procedure is recommended:

1. Drain the coolant. Refer to "Draining Coolant" in this section.
2. Remove the heater core inlet hose from the thermostat outlet.
3. Remove the heater core return hose from the block inlet.
4. Place the end of the heater core return hose in a container and apply low pressure shop air 35 kPa (5 psi) to the heater core inlet hose to blow the coolant out of the heater core.



5. Install the heater core inlet hose to the thermostat outlet.
6. Install the clamp at the 12 o'clock position.



7. Install the heater return hose to the thermostat outlet.
8. Install the clamp at the 12 o'clock position.
9. Prepare a mixture of automatic dishwasher detergent and water at the ratio of 2 ounces (dry measure) to 3.8 Liters (1 gal) of water.
10. Remove the engine thermostat to permit the automatic dishwasher detergent and water mixture to circulate through the engine and the radiator.
11. Fill the cooling system with the detergent and water mixture.
12. Run the engine for 5 minutes.
13. Drain the cooling system.
14. Repeat steps 9-13.
15. Fill the cooling system with clean water.
16. Let the engine run 5 minutes.
17. Drain the cooling system completely.

Notice: If the cooling system has been contaminated by oil, replacement of the thermostat and water pump is required.

18. Install the new engine thermostat. Refer to "Thermostat Inlet Housing and Element Installation" procedure in this section.
19. Install new water pump. Refer to "Water Pump Replacement (In-Vehicle)" procedure in this section.

Important: The vehicle must be level when filling with coolant.

20. Fill cooling system. Refer to "Coolant Replacement" procedure in this section.