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How to service or repair the Leafield Marine C7 inflatable boat valve

After a few years of faithful service, the rubber diaphragm on a RIB/Inflatable Boat Leafield Marine C7 inflation valve can fail as either the rubber material becomes brittle and fails to ‘seat’ properly within the inflation valve, or the spring or plastic diaphragm spindle can fail. Replacing the Leafield Marine C7 inflation valve diaphragm is a straightforward job and the service kits are available from ribstore.

To service your Leafield Marine C7 valve, you will need:

Refer to diagram below of the valve assembly to familiarise yourself with the inflation valve and its components, before you start the job.

  1. Deflate the collar/tube and lay the deflated tube flat so that you are able to place downward pressure on the valve body, whilst being able to grip the section of the valve that sits within the tube, through the tube fabric, to prevent it turning.
  2. Using the C7 wrench unscrew the outer/male section of the valve counter clockwise, ensure that the inner/female section of the valve, inside the tube, remains in place so that it is not lost within the tube once the outer section has been unscrewed.
  3. Retain the large black plastic sealing washer and push and turn the valve diaphragm spindle so that it is locked in the ‘open’ position. If this sealing washer is grey coloured or perished, then this should be replaced – see
  4. Remove the black rubber diaphragm/core seal from the end of the spindle by pulling off the end of the spindle, then return the spindle to the ‘closed’ position and remove the old spindle and spring by sliding out from the front of the valve.

    Leafield Marine C7 Valve

  5. Install the new spring and spindle and then once again lock the spindle in the ‘open’ position. Attach the new diaphragm onto the end of the spindle; ensure the rubber diaphragm is properly attached to the spindle and that the plastic flange on the end of the spindle is visible and has locked the rubber diaphragm in place.
  6. Unlock the spindle and test the diaphragm spring movement. Check that the rubber diaphragm seats properly onto the valve body so that air will not escape once the valve is re-installed.
  7. Take a firm grip of the inner/female section of the valve that sits within the tube through the tube fabric to prevent it turning, and then re-install the outer/male section into the outer/female section by turning clockwise until hand tight. Remember to re-install the black plastic sealing washer with the ridges facing the tube fabric.
  8. Use the C7 wrench to fully tighten the valve. Re-inflate the tube/collar and then test for leaks by spraying some soapy water around the valve and checking for any bubbles. Further tighten the valve using the C7 wrench if any leaks are apparent.

View & Download a PDF Version of this Guide HOW TO replace a C7 valve diaphragm