Caution: As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the solution in the radiator without causing the solution to boil. Removal of the pressure 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 the engine, fenders and the person removing the cap.

NOTICE: When adding coolant, it is important that you use GM Goodwrench DEX-COOL® or HAVOLINE® DEX-COOL® coolant. If Coolant other than DEX-COOL® or HAVOLINE® DEX-COOL® is added to the system the engine coolant will require change sooner; at 50 000 km (30,000 mi) or 24 months.

Ethylene glycol/water fill ratios have been established to ensure a minimum of 50 percent ethylene glycol in the coolant flush and drain procedure, and ensuring that all engine block drains and air bleeds were utilized.

The cooling system capacity for the 3400 (LA1) engine with front heating system only and base cooling is 9.1 liters (9.5 quarts), and with rear heating and base cooling is 11.6 liters (12.1 quarts. The front heating system only with heavy duty cooling (RPO VO8) is 10.1 liters (10.5 quarts), with rear heating and heavy duty cooling is 12.6 liters (13.2 quarts.The coolant recovery reservoir capacity is 0.99 liters (1 quart) to the COLD mark on the reservoir. The quantities listed in the filling procedure include the additional quantity to displace the air remaining in the coolant system after a static refill.

Using the correct fill ratio and the following procedures will ensure a minimum concentration of 50 percent ethylene glycol in the coolant system and simplify the customer fill task. Refer to Engine Cooling System Specifications for static fill radiator capacities. Every five years or 240,000 km, (150,000 miles), whichever occurs first, the cooling system should be drained and filled using the following recommended procedures.

Important: This procedure significantly increases the amount of used coolant and diluted hazardous waste.

1. Park the vehicle on a level surface.
2. Remove and clean coolant recovery reservoir.
3. Remove the radiator cap when the engine is cool, by:

3.1.	Slowly rotating the cap counterclockwise to detent. Do not press down while rotating pressure cap.

3.2.	Wait until any residual pressure (indicated by a hissing sound) is relieved.

3.3.	After all hissing stops, continue to rotate counterclockwise until the cap is removed.

Important: Recover coolant and store in a used coolant holding tank and submit the used coolant for recycling on a regular basis. This procedure significantly increases the amount of used coolant and diluted hazardous waste.

4. Place drain pan under vehicle to collect all drained coolant.
5. 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.




6. Open the air bleed vent on the thermostat housing (1) and above coolant pump. The air bleed vent should be opened two to three turns.



7. Remove both engine block drains. The front engine block drain is located between the starter and the engine oil filter. The rear engine block drain is located by the engine crank sensor.

Important: Dispose of used coolant in a proper fashion, i.e., 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!

8. Allow the coolant to drain completely.

1. Close the radiator drain valve. Reinstall all engine block drains.
2. Remove the coolant recovery reservoir and empty. Flush the reservoir with clean water, drain and reinstall.

Important: 

•	When refilling the engine coolant system, add three engine coolant supplement sealant pellets, GM P/N 3634621 or equivalent, and GM approved new Ethylene Glycol Coolant DEX-COOL™ GM P/N 9985809.

•

If the cooling system is being refilled ONLY (no flush), a 50 percent ethylene glycol and 50 percent clean water mixture should be used to fill the system. Fill the system until the level of the 50/50 mixture has reached the base of the radiator neck. Wait two minutes and recheck the level of the coolant mixture, add a 50/50 ethylene glycol/water mixture as necessary to restore the coolant mixture level to the base of the radiator neck.

3. Slowly fill the cooling system through the radiator neck using the following procedure:

3.1.	If the coolant system has been flushed first add 100 percent ethylene glycol in the amount listed in the graphic for the appropriate engine application.

3.2.	Slowly add clean water to the system until the level of the coolant mixture has reached the base of the radiator neck.

3.3.	Wait for two minutes and recheck the level of the coolant mixture. Add clean water if necessary to restore the coolant mixture level to the base of the radiator neck.

4. Install the radiator cap making certain the arrows line up with the overflow tube.
5. Close all air bleeds. DO NOT over-torque the air bleed valve. The air bleed valve is made out of brass.
6. Fill the coolant reservoir with a 50 percent ethylene glycol and a 50 percent clean water coolant mixture.

Notice: The Low Coolant warning/indicator lamp may come on after this procedure. If after operating the vehicle so that the engine heats up and cools down three times, the Low Coolant warning/indicator lamp does not go out, or fails to come on at the ignition check, and the coolant is above the full cold mark in the reservoir, refer to Low Coolant Warning/Indicator Lamp in Electrical Diagnosis. If at any time the Temperature warning/indicator lamp comes on, immediate action is required. Turn OFF the engine and allow the vehicle to cool. Do not remove the coolant recovery reservoir cap at this time.

7. Inspect the freeze protection of the engine coolant after the engine heats up and cools down three times using a refractometer or a thermohydrometer to ensure proper freeze -37°C (-34°F) protection. Obtain the coolant mixture for the inspection from the base of the radiator neck, NOT from the coolant recovery reservoir.