How to Flush a Cooling System 4.3

by Gregory Crews
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The coolant system in a 4.3 liter engine requires a water and antifreeze mix to keep the coolant system running strong through the coolant lines throughout the engine. Flushing the radiator will flush any debris and sediment that have accumulated through the engine and radiator. It is essential that the coolant system has a 50 percent mix of antifreeze and water. A premixed coolant will help to ensure the mix is accurate.

Step 1

Open the hood for access to the engine compartment. Ensure the truck has been parked for at least an hour so the engine will be cool. Twist the radiator cap counterclockwise and remove it from the radiator. Place it to the side.

Step 2

Place a drain pan under the radiator to catch the coolant. Unscrew the hose clamp on the bottom radiator hose with a flat tip screwdriver. Pull the hose off the radiator by hand. Allow all the coolant to drain into the pan.

Step 3

Place a garden hose into the opening on the top of the radiator. Turn the hose on and allow it to cycle through the radiator. Start the truck and allow it idle while the hose is running. The engine will warm up and allow the thermostat to open. Watch the water as it flows out of the radiator. When the water pouring out of the bottom is clear and clean, the radiator and coolant lines are successfully flushed.

Step 4

Turn the truck off. Tighten the hose back onto the radiator by pushing it back onto the inlet pipe. Tighten the hose clamp with a flat tip screwdriver.

Step 5

Pour in premixed coolant until the radiator is full. Start the truck and allow it warm up. The truck should be warm because it was idling during the flushing phase.

Step 6

Continue filling with coolant. Once the thermostat opens, the level will drop and require additional coolant. Pour until the system cannot hold any more coolant. Tighten the cap back onto the radiator when it is full.

Step 7

Turn the truck off and close the hood.

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