How to Fix a Gate Valve That Doesn't Close

Turn off the main water supply valve to your home. Open up the faucet nearest to gate valve that doesn't close. This will drain the water from the line. If the faulty gate valve is on the hot water pipe, turn off the circuit breaker to the water heater.

Drain the water heater before repairing the gate valve if the gate valve is on a hot water line. There is a drain spigot at the bottom of the water heater. Attach one end of a garden hose to the drain and place the other end outside or in a nearby tub. Open the drain valve and allow the water to drain completely.

Hold the body of the gate valve on the neck below the handle with a pair of slip-joint pliers. Turn the nut at the base of the handle and valve body counterclockwise with an adjustable wrench while holding the gate valve steady with the slip-joint pliers.

Pull the handle straight out of the gate valve body. Shine a flashlight into the open cavity of the gate valve. Look for debris or lime scale at the bottom of the gate valve.

Brush white vinegar vigorously inside the gate valve body with a small toothbrush. Allow the vinegar to sit for 15 minutes. The vinegar will loosen the sediment in the gate valve cavity.

Insert a stiff-bristle fitting brush into the gate valve body and twist the brush left to right, scrubbing the lime scale and sediment loose.

Remove the loose debris with a soft cloth. Spray compressed air into the valve to remove small particles as necessary.

Hold the gate valve handle in one hand and turn the gate on the threaded rod 1/4-turn clockwise with your other hand. This lowers the gate slightly. The gate is a circular machined plate that threads onto a shaft at the bottom of the handle.

Thread the handle back into the gate valve body. Hold the body with slip-joint pliers and rotate the handle nut clockwise with the adjustable wrench until it is tight.

Close the drain valve on the water heater and remove the hose if working on a hot water line. Turn on the water supply to the house. Allow the water heater to fill completely before turning on the circuit breaker to the unit.