Flushing the Cooling System

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.
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:

CAUTION: DO NOT REMOVE CAP OR OPEN COOLING SYSTEM DRAINS FROM A HOT SYSTEM. ALLOW SYSTEM TO COOL FIRST.

1. Drain coolant. (Refer to "Coolant Check and Replacement".)





2. Remove heater core inlet hose from water pump outlet.
3. Remove heater core return hose from head bridge.
4. Place end of heater core return hose in a container and apply low pressure shop (35 kPa [5 psi]) air to the heater core inlet hose to blow coolant out of heater core.
5. Install heater core inlet hose to heater water pump.
6. Install clamp at 12 o'clock position
7. Install heater core return hose to return inlet fitting.
8. Install clamp at 3 o'clock position
9. Prepare a mixture of Calgon (R) or equivalent (automatic dishwasher detergent), and water at the ratio of two ounces (dry measure) to 3.8 Liters (1 gal.) of water.
10. Remove the engine thermostat to permit the Calgon (R) or equivalent and water mixture to circulate through the engine and the radiator.
11. Fill the cooling system with the Calgon (R) or equivalent solution.
12. Run the engine for 5 minutes.
13. Drain the cooling system.
14. Fill the cretin item with clean water
15. Repeat Steps 11 through 14.
16. Let the engine run 5 minutes.
17. Drain the cooling system completely.

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

18. Install new engine thermostat (refer to "Thermostat Inlet Housing and Element Installation").
19. Install new main water pump (refer to "Water Pump Removal and Installation").
20. Fill cooling system. (Refer to "Coolant Check and Replacement".)
21. Using fresh water to rinse away any coolant that was spilled during service.