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My rear tire Presta valve began giving me some problems this morning. I noticed that the top screw (typically unscrew/screw this to inflate/deflate) was screwed too tightly to the valve pin thread and subsequently to the core. With a pair of pliers I was able to get the screw off but with it came the thread from inside the valve. I know how to screw the core back into the tube thread, but can't figure how to get the valve thread to attach/stay inside the core so that I can put it all back together and inflate the tire?

Have attached a picture showing the tire stem, the vale core, and pin thread/screw so you can understand how things have come apart.

Any thoughts on how to get the thread back together with the valve core?

enter image description here

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  • Replace the core with one from a spare tube. To remove the core from the spare use one of the circular style spoke wrenches -- a fairly large slot in the wrench will engage the top of the core without being blocked by the knurled tip of the plunger. (Though if there are parts of the old valve rattling around in the tube it would be wise to replace it, as the loose parts will probably eventually cause the tube to fail.) Sep 4 '16 at 2:11
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The brass rod (I believe its technical name is the "plunger rod") is broken. You can probably find the lower part hanging out in the tube somewhere. Getting it out may be tricky, but you should probably do so before replacing the core.

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  • Thanks. Any tips on how best to get the plunger rod out? Alternatively is there significant danger in simply replacing the core and filling the tube up with the plunger inside?
    – ccdrm
    Sep 3 '16 at 19:08
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    I believe that with the tube out, you should be able to hold the tube with the stem at the 6 o'clock position, shake it so the broken plunger drops down there, grab it with your fingers through the tube wall and work it through the valve stem. That's the best I can come up with. Sep 3 '16 at 19:42
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When I have a dead tube where a patch doesn't work, I check the valve and save the core if its removable.

Your quick fix is to replace the valve core, cos the tube is probably fine.

Of course with the valve like this you can't inflate it, and you can't ride it, so swapping the tube for a spare, and fix/test it at your leisure.

(actually I save the complete valve most of the time... Schrader valves make for great water bottle rockets, a fun kid project for summer. )

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