Could someone please enlighten me if my valve is broken? I think this is a Dunlop valve but the core seems completely stuck to the cap. No matter how much I twist and turn the core always comes off and the tire deflates. There is nothing inside the tube in the picture, it leads directly inside the tire. I can inflate the tire when the core is off but then there is no way to reattach is fast enough because there is literally nothing stopping the air. Thank you in advance!

Here is what comes off the tire no matter what I do Here is what the tube looks like when the cap with the core is off

  • Can you remove the cap from the valve core, replace the core in the valve stem (i.e. at the wheel), and pump up the tire? The valve should work fine without the cap, so you can just throw it away. You can buy new valve cores, or you can just replace the tube.
    – Erlkoenig
    Commented Feb 9, 2022 at 19:12
  • 1
    If you replace the tube, consider going to Schrader valves (aka car valves) which will use the same sized hole in the rim. Check your pump can handle them (Guess how I know that!)
    – Criggie
    Commented Feb 9, 2022 at 23:56
  • Hold the lower part (metal) of the insert with one hand while unscrewing the cap with the other. After pumping the tyre don't tighten the cap too hard.
    – Carel
    Commented Feb 12, 2022 at 10:25

1 Answer 1


If you can't get the black plastic cap off of the valve core, you'll need to replace the core. I would take a couple pair of pliers and secure one around the textured part of the core and use the other pair to try and twist off the black cap. Alternatively, you can use a Dremel type rotary tool with a cut blade and score a line through the black plastic cap. You may saw two lines on opposite sides of the cap to improve the releasing of the black cap. In any case, that black plastic cap must come off the core in order for the core to be of any use. Removing the black cap will not affect the air tightness of the system as that is accomplished by a ball bearing or spring loaded rubber within the core itself. It is indeed a Dunlop valve with a modern core you are dealing with. Wikipedia article on Dunlop valve

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