Draining and Refilling the Coolant System

Whenever the cooling system experiences a major loss of coolant such as a broken hose or any time engine service is performed which requires draining of the system, the following procedure should be used.

IMPORTANT: BLOCK DRIVE WHEELS, place transmission in PARK (automatic transmission), or NEUTRAL (manual transmission) and set the parking brake.

1. Remove radiator cap when engine is cool by:

- Slowly rotating cap counterclockwise to detent. (Do not press down while rotating).
- Wait until any residual pressure (indicated by a hissing sound) is relieved.

- After all hissing ceases, press down on cap while continuing to rotate counterclockwise.

CAUTION: To avoid the danger of being burned, do not remove radiator cap while engine and radiator are still hot. Scalding fluid and steam may be blown out under pressure.

2. Remove thermostat by using the wire handle to lift it out of the housing.

3. With the thermostat removed, reinstall the thermostat housing cap.

4. Open radiator drain valve and block drain plugs to drain coolant. Open coolant pipe plugs.

5. Close valve. Reinstall drain plugs and add sufficient water to fill system.

6. Run engine, drain and refill the system, as described in steps 4 and 5 a sufficient number of times, until the drained liquid is nearly colorless.

7. Allow system to drain completely. Then close radiator drain valve tightly, and reinstall block and coolant pipe drain plugs.

8. Remove recovery cap leaving hoses in place. Remove coolant recovery tank and empty of fluid. Flush tank with clean water, drain and reinstall.

9. Add sufficient water and ethylene glycol coolant meeting GM Specification 1825-M, to provide the required freezing and corrosion protection - at least 50% solution -37 degrees C (-34 degrees F).

Fill radiator to the base of the radiator fill neck and add sufficient coolant to the recovery tank to raise the level to the "FULL" mark. Reinstall recovery tank cap.

10. Run engine, with radiator cap or thermostat housing cap removed, until normal operating temperature is reached. (Radiator upper hose becomes hot.)

11. With engine idling, add coolant until level reaches bottom of filler neck and reinstall thermostat and cap and radiator cap making certain arrows line up with overflow tube.

CAUTION: UNDER SOME CONDITIONS, THE ETHYLENE GLYCOL IN ENGINE COOLANT IS FLAMMABLE. TO HELP AVOID BEING BURNED WHEN ADDING COOLANT, DO NOT SPILL IT ON THE EXHAUST SYSTEM OR HOT ENGINE PARTS.
It is the owner's responsibility to keep the freeze protection at a level appropriate to the temperatures which may occur in the area of vehicle operation.

- Maintain cooling system freeze protection at -37 degrees C (-34 degrees F) to ensure protection against corrosion and loss of coolant from boiling, even though freezing temperatures are not expected.

- Add ethylene glycol base coolant that meets GM Specification 1825-M, when coolant additions are required because of coolant loss, or to provide additional protection against freezing at temperatures lower than -37 degrees C (-34 degrees F).

- NOTICE: Alcohol, methanol base coolants, or plain water are not recommended at any time.

Engine cooling, the protection level should be maintained to at least -37 degrees C (-34 degrees F).

Dealer Service Bulletins and Service Manuals are available through HELM, INCORPORATED, P.O. Box 07130, Detroit, MI, 48207, or by calling HELM at 1-800-782-4356.