How to Inject Tyre Sealant into a Presta Valve Tube

I have lots of nice water based tyre sealant for so many things from wheelbarrow, bicycles, motorcycles to cars that use standard (schrader) valves. The method is to remove the core, pour in the sealant, replace core, turn wheel to puncture at bottom for liquid to gravitate to hole, and seal it.

The catch with Presta valves is you typically can’t remove the core, aslo known as the valve needle.  This instruction starts off when you have a Presta tube.

  1. Unscrew the valve tip nut by hand
  2. At its outer limit, use small tactile grippy nose pliers to continue unscrewing, effectively stripping the 0.2mm of retaining cap on the valve needle (core).
  3. Carefully trap/remove the tiny stripped sharp strand(s) of metal so they don’t find the nearest skin or tube to stab.
    Pay special attention to the needle tip, as we want to lose this inside the tube for easy low pressure filling, before fishing it out again.
  4. Use an air pump to barely inflate the tyre, so the valve needle pops into the tube.
    You can raise the tube and hear/feel it has fallen at the bottom.
  5. Use a syringe with 4mm coupling fuel safe hose (or any method that works for your syringe diameter) to load the syringe, and transfer the load via the valve into the tube.
    Inject at the valve high, so that it gravity drops to the low point of the tube, otherwise it will pour out.
  6. After the desired sealant volume has been injected, reach for the bottom of tube to fish out the valve needle.
  7. Finger pinch shut the tube near the valve.
  8. Raise the bottom of tube above the the valve area, so the needle drops down nearer to the valve.
    You still have the tube pinched so the sealant doesn’t run out the valve.
  9. Feel for the narrow end of the needle, and thread it into the valve base.
    Lower the rest of the tube, and with the valve at high point, tap it on a bench to release the valve needle back out.
  10. Re-attach the valve needle nut.
    Walla! You now have a no cost/adapters Presta valve tube with tyre sealant.

Remember to let the wheel rest with the valve at the top before you do any inflating or deflating. This way the sealant can gravitate to the bottom and won’t explode out. Do it once so you know what I mean. Alternatively, add red food colouring to the sealant, and you can have blood/gore movie effects when it explodes out of the valve :)

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