How to Change a Radiator Bleed Valve

Position #1 is radiator bleed valve.

Bleed valves are designed to release the build up of air pressure in a car's radiator. Depending on the heat and stress the engine has been exposed to, you may have to replace this valve on a regular basis. If not, then pressure will build, trapping the radiator fluid and not allowing it to flow and cool the engine. You can change the radiator bleed valve with relative ease, and have the option of replacing only the valve or the entire mounting unit.

Things You'll Need

• Drain pan
• Crescent wrench
• Socket wrench
• Socket set
• Radiator bleed valve or complete unit with valve

Instructions

1. Park the car on a level surface, engage the parking brake, and open the hood.

2. Disconnect the negative cable from the battery.

3. Remove the fill cap from the radiator. Open the radiator bleed valve as far as it will go by twisting the key, or knob on the top of the valve.

4. Place the drain pan directly beneath the radiator drain plug. The location of the drain plug will depend on the radiator model; consult your vehicle owner's manual for the exact location. Unscrew the drain plug just enough to begin draining the antifreeze into the pan. Wait until the antifreeze stops flowing before continuing.

5. Remove the radiator bleed valve either by using a crescent wrench to loosen the lock nut at the base of the valve directly above the bleed valve unit, or by using a socket wrench to remove the small bolts that attach the entire unit to the engine support. If you are removing the entire unit, once the bolts are undone you will have to pull the radiator hoses off the unit in order to remove it.

6. Install the replacement radiator bleed valve or unit. Installation is the reverse of removal. Make sure that if you are installing only the bleed valve that you do not force the valve into the unit, or over-tighten the lock nut. When you are done, re-tighten the radiator drain plug, and refill the radiator with antifreeze.

Tips & Warnings

• You can change the valve without draining the radiator system completely, simply remove enough fluid to empty the top hoses.

• Make sure the engine is cool to the touch before beginning, let the vehicle sit for at least a 1/2 hour to cool down.

Resources

• Read this Article in Portuguese
• Autoshop 101