How Do I Fix a Broken Gate Valve Restricting Water Flow?

Written by robert sylvus
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How Do I Fix a Broken Gate Valve Restricting Water Flow?
Gate valves are designed to operate fully opened or closed. (old valve image by Vonora from

An operator who fails to fully open or close a gate valve shortens the valve's life expectancy. A gate valve uses a disk that slides up and down seats (the sealing edges that hold the disk in place) inside of the valve's housing to stop water. A threaded stem, with a handle on top, operates the disk. When the disk restricts water it vibrates against the housing. Eventually the vibration creates damage. Failure to fix broken internal gate valve parts can cause unrepairable damage to the gate valve's housing.

Skill level:

Things you need

  • Bucket
  • Adjustable wrench
  • Open-ended wrench set
  • Rag

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  1. 1

    Turn off the water pressure to both sides of the gate valve by turning off the valve at the water meter and opening a faucet.

  2. 2

    Place a bucket under the gate valve.

  3. 3

    Hold the gate valve's housing still with an adjustable wrench. Loosen the compression nut holding the gate valve's stem in place with the proper sized open-ended wrench. Any remaining water pressure in the water lines will force water through the loose compression nut. Allow the water to finish leaking before continuing.

  4. 4

    Loosen the gate valve's bonnet, the part of the gate valve where the stem enters the valve's housing. Some bonnets screw into the valve's housing. If this is the case, hold the housing still with the adjustable wrench and turn the bonnet with the proper sized open-ended wrench. If the bonnet bolts to the housing, hold the housing still with the adjustable wrench and remove the bolts with the proper open-ended wrench.

  5. 5

    Lift the bonnet out of the gate valve's housing. The disk should exit the housing with the bonnet.

  6. 6

    Clean the valve's seats (the grooves the disk follows inside of the valve's housing) with a rag. Inspect the seats. If the seats are damaged, replace the valve. Damage includes broken or chipped edges, large grooves that allow water to pass and obvious wear. If part of the seats shine and the rest of the seats have a dull appearance, double-check the shiny area for vibration-caused wear. Large amounts of wear will cause the disk to hang up.

  7. 7

    Inspect the disk. Replace an out-of-round disk or one with broken, grooved or worn edges. A slot, located along the top of the disk, locks the disk to the bottom of the valve's stem. To replace the disk, slide the stem out of the slot.

  8. 8

    Open and close the stem fully with the stem's handle. Replace the stem if it sticks or does not turn freely. Most stems unscrew from the bonnet.

  9. 9

    Reassemble the gate valve. Slide the bonnet with its stem and disk back into the housing. Lightly tighten the bonnet. Open and close the gate valve with the handle several times. If the valve fully opens and closes without sticking then hold the gate valve's housing with the adjustable wrench and tighten the bonnet and the stem's compression nut with the proper open-ended wrenches.

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