Coolant: Service and Repair
DRAINING, FLUSHING AND FILLING THE COOLING SYSTEM
CAUTION: As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the ablution in the radiator, without causing the solution to boll. Removal of the surge tank cap while the engine is hot and pressure is high will cause the solution to boil instantaneously - possibly with explosive force spewing the solution over engine, fenders and person removing the cap. Under some conditions the ethylene glycol in engine coolant is combustible.
NOTICE: When adding coolant, it is important that you use GM Goodwrench DEX-COOL coolant. If coolant other than DEX-COOL is added to the system, the engine coolant will require change sooner - at 50,000 km (30,000 miles) or 24 months.
Before draining and recovering the cooling system, inspect the system. Perform any service needed to ensure that the system is clean, does not leak and is in proper working order.
Some coolant manufacturers are mixing other types of glycol in their coolant formulations; propylene glycol is the most common new ingredient, However, propylene glycol is not recommended for use In GM vehicles that were manufactured with GM Goodwrench DEX-COOL. A hydrometer will not always provide a correct measurement of freeze protection when anything other than ethylene glycol and water is being tested. The degree of inaccuracy will vary depending on the proportion of other glycols present in the coolant. Hydrometers test the amount of glycol in a mixture by measuring die specific gravity of the mixture; the more ethylene glycol, the higher the float balls go, and the better the freeze protection. Because ethylene glycol and propylene glycol do not have the same specific gravities, hydrometer readings of mixtures containing propylene glycol give incorrect values. It is recommended that a "refractometer" be used when testing coolant Refractometers test for the amount of glycol in a coolant mixture by measuring the speed of light as it passes through the fluid and are not affected by the specific gravity of the glycol. For proper coolant testing, refer to "Coolant Concentration Testing" in this Section.
DRAINING
1. Park the vehicle on a level surface.
2. Remove the surge tank cap, when the engine is cool, by:
^ Slowly rotating cap counterclockwise about a 1/4 turn and then stop.
^ Wait until any residual pressure (indicated by a hissing sound) is relieved.
^ After all hissing stops, continue to rotate counterclockwise until the cap is removed.
3. Insert piece of 5/16 inch. fuel line tubing (or equivalent) through lower tie-bar and over the radiator drain.
4. Open the radiator drain valve located at the bottom of the radiator tank.
^ For procedures requiring the cooling system to be partially drained, opening the radiator drain valve should provide sufficient draining; and no further actions should be necessary.
5. Remove engine block drain plug.
6. Allow the coolant to drain completely.
Important: Dispose of used coolant in a proper fashion, i.e., in a used coolant holding tank. NEVER POUR USED COOLANT DOWN THE DRAIN! Ethylene glycol antifreeze is a very toxic chemical; disposing of it into the sewer system or ground water is both illegal and ecologically unsound!
Inspect
^ The drained coolant:
- If the coolant is discolored, flush the cooling system.
- If the coolant appearance is normal, continue with the filing procedure.
FLUSHING
Various methods and equipment may be used to flush the system. If using special equipment such as a back flusher, follow the manufacturer's instructions. However, the thermostat should be removed before flushing the system.
FILLING
NOTICE: When adding coolant, it is important that you use GM Goodwrench DEX-COOL coolant. If coolant other than DEX-COOL is added to the system, the engine coolant will require change sooner - at 50,000 km (30,000 miles) or 24 months.
1. Close the radiator drain cock and remove the drain hose.
2. Reinstall engine block drain plugs if previously removed.
^ Use pipe sealer GM P/N 12346004 when installing drain plugs.
3. Fill the surge tank to the base of the filler neck.
Important ON VEHICLES EQUIPPED WITH THE 3.1L ENGINE: Open the coolant air bleed valve on the top of. the thermostat bypass pipe/heater pipe assembly. Once a continuous stream of coolant is expelled from the valve, close the valve.
4. With the pressure cap off, start the engine and let it run until the upper radiator hose starts to get hot.
5. If the coolant level in the surge tank is low, add the proper mix of coolant until the the level reaches the "Split Line".
6. Install the cap onto the tank with hand tight pressure.
^ After servicing the cooling system, an occasional intermittent low coolant light (if equipped) may be encountered during some extreme driving maneuvers. This complaint should be eliminated by removing the surge tank cap and adding coolant to a level just at or above the "Split Line" when the system is cold.