How to Refill the Coolant without a Bleed Tool

Draining and refilling the coolant is one of the easier maintenance tasks you can do on most vehicles. In addition to saving money, doing your own maintenance is a way to monitor the health of your vehicle.

Why Perform a Regular Coolant Flush and Refill?

Coolant loses effectiveness over time, so it’s important to periodically drain and refill the cooling system. In addition, as coolant becomes dirty, and rust and particles can eventually degrade cooling system components, such as the engine and water pump.

Bleeding Air from the Cooling System

If you drain the system and then pour coolant in, there is still air trapped within the hoses and components that hold coolant. That air must be removed. You’ll need to bleed out the air and then top off the coolant to the proper level.
Some car manufacturer refill procedures use a special tool that automatically fills the cooling system and bleeds any excess air. In most cases, if you don’t have the special tool, you can still fill the cooling system and bleed it manually. In rare cases, vehicles need to be serviced with specialized cooling system equipment, due to the complexity of the cooling system. Air will become trapped in the cooling system, and cause the engine to overheat! Check the service information before you attempt the procedure.

Research the vehicle’s cooling system.

How to Refill the Coolant System Manually

Caution
Do not work on the coolant system when the system is hot and under pressure: Coolant can cause serious burns. Do not remove the radiator cap, cylinder block drain plugs, or loosen the radiator draincock, when the engine is hot.

1. Tighten the radiator draincock.

Tighten the radiator draincock. 2010 Chevrolet HHR shown. Image: General Motors

2. Tighten the cylinder block drain plug(s).

Tighten the engine block drain plug. 2010 Chevrolet HRR shown. Image: General Motors.

3. Fill the cooling system with the manufacturer-specified antifreeze. You can find the correct specification in your Chilton DIY subscription or in your owner’s manual. Because specifications change occasionally, such as with new technology, it’s a good idea to check the technical service bulletins in your ChiltonDIY subscription too.
4. Fill the radiator to the top and install the radiator cap. Add sufficient coolant to the overflow tank to raise the level to the FULL mark. Check your Chilton DIY specifications or the owner’s manual for the coolant amount including the overflow tank.

Fill the radiator to the top and install the radiator cap. 2010 Chevrolet HHR shown. Image: General Motors.

5. Run the engine with both the radiator cap and reservoir/overflow tank cap in place. Turn on the heat with the blower on high. When the engine reaches normal operating temperature, shut the engine off and allow it to cool.
6. Top off the coolant level to the reserve/overflow tank as necessary to bring it to the FULL mark. Only add coolant when the engine is cold. The coolant level in a warm engine will be higher due to thermal expansion – that is, hot coolant expands and so the coolant level will appear to be higher.
7. Repeat the procedure and recheck the cooling system level.