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  1. #1
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    Stan's Clogging Valve cores

    This is becoming a very common and very annoying issue on my mountain bikes. I run tubeless with Stan's and it works great, but after a few months my valve cores become sized-up with Stans and unable to take -in air quickly, or at all, and in my last case, the valve core itself became so clogged, it would not take-in any air, so I went to unscrew it from the rim, and couldn't even do that -- the Stan's had apparently sized the threads. I needed up having to hacksaw the valve core in half to get it out of the rim.

    Any solution to this?
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  2. #2
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    Quote Originally Posted by XCFred
    This is becoming a very common and very annoying issue on my mountain bikes. I run tubeless with Stan's and it works great, but after a few months my valve cores become sized-up with Stans and unable to take -in air quickly, or at all, and in my last case, the valve core itself became so clogged, it would not take-in any air, so I went to unscrew it from the rim, and couldn't even do that -- the Stan's had apparently sized the threads. I needed up having to hacksaw the valve core in half to get it out of the rim.

    Any solution to this?
    why on earth would you have to saw a presta valve core in half to remove it from a rim?!?
    when i remove the cores to add sealant i just pull of any gummed up latex on them before putting them back in. no issues.
    replacement cores are $2
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  3. #3
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    You should probably use tubes if a hacksaw is your solution...


    Seriously, the only way Stans would prevent your valve stem from being removed is if it was leaking on the OUTSIDE of the stem. And even then any corrosion it might cause could be alleviated by a drop of penetrating oil at the valve stem nut.

  4. #4
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    Quote Originally Posted by XCFreb
    so I went to unscrew it from the rim
    wait a minute... your valve cores are screwed into your rim?
    somethin' ain't right...
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  5. #5
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    I think the OP means that he uses valve cores that have a threaded post and attached the threaded ring on the outside..Right?
    Solution: Use a little grease next time you screw down the threaded ring. The grease will displace any latex and not let any get on/under the threads. Next time it gets stuck, try a little vinegar around the outside and either channel locks or vise grips to free it.

  6. #6
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    Quote Originally Posted by Yogii
    I think the OP means that he uses valve cores that have a threaded post and attached the threaded ring on the outside..Right?
    Solution: Use a little grease next time you screw down the threaded ring. The grease will displace any latex and not let any get on/under the threads. Next time it gets stuck, try a little vinegar around the outside and either channel locks or vise grips to free it.
    That is the valve stem, not the valve core.
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  7. #7
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    Quote Originally Posted by shiggy
    That is the valve stem, not the valve core.
    Yeah OK, the valve stem then. -- my bad. What is the valve core?

    I had to remove it from the rim because it was useless; it was so seized by the Stan's that air wouldn't go in at all. The damn thing WOULD NOT unscrew from the rim, even after trying to use an adjustable wrench on it. Not sure if it makes a big difference, but this was a Mavic valvestem. The Bontragers I'm using seem to have a better area to get a grip to tighten/loosten, although they are also having the issue with clogging.

    I'll definitely be sure to put a dab of oil on them in the future to prevent the valve stem from seizing on the rim, but not sure how to prevent the valve from becoming clogged again.
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  8. #8
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by XCFred
    Yeah OK, the valve stem then. -- my bad. What is the valve core?

    I had to remove it from the rim because it was useless; it was so seized by the Stan's that air wouldn't go in at all. The damn thing WOULD NOT unscrew from the rim, even after trying to use an adjustable wrench on it. Not sure if it makes a big difference, but this was a Mavic valvestem. The Bontragers I'm using seem to have a better area to get a grip to tighten/loosten, although they are also having the issue with clogging.

    I'll definitely be sure to put a dab of oil on them in the future to prevent the valve stem from seizing on the rim, but not sure how to prevent the valve from becoming clogged again.
    The valve core (the movable part inside the valve stem) did cog. It is also removable (for both the Mavic and Bonty valves) and can be cleaned as MF has mentioned. The Mavic and Bonty valves are not interchangeable with other than their own rims.

    The nut that holds the valve stems to the rims is round. An adjustable wrench is not going to grip it at all. If you were trying to remove the valve stem using the flats near the end of the valve that will not work. Those are on the valve core (and both Mavic and Bonty supply a small plastic wrench to remove the core) and used to remove the core. Will not loosen the valve stem to remove it.

    I have no idea how you cut the stem to remove it if you could not loosen the nut that was tight against the rim.
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  9. #9
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    Ah hah! I did not know you could remove just the core...that would've been nice to know!

    I will have to get that tool so I can pull out the core on my Bonti wheel and try to de-clog it.
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  10. #10
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    I had the same issue. It was prob 80 percent clogged so it pumped up very slowly with lots of resistance. What I did that worked to free the clog was to slowly pump the tire up to 40 PSI then depress the valve. Basically using the tire itself as an air compressor to blow the clog out far enough that I could pull the rest of it out with my fingers. Pumped the tire back up with no more problems.

  11. #11
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    Every time I park my bikes, I position the tubeless valve stems so that the sealant will hopefully run downward, back into the tires. This is not scientific, just my GUT feeling.

  12. #12
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    I grease the cores before installing them. For very troubled valves I have a sharp pick that fits inside and I just poke out any dries sealant

    sent with a telegraph

  13. #13
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    I remove the core and then stick in backwards into the silca head of my prestaflator hooked to my air compressor and hit it with 100 psi. You have to depress the presta head of the valve to let the air flow out and hopefully push the clogging bits out with the air. If that doesn't work, I go to work with a safety pin to pull the gunk out. Sometimes I'll turn the valve around in the silca head and hit it with high psi that way, too. Whatever it takes to clear out the clog.

  14. #14
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    You should only inflate or let air out of your tires with the valve stem on the bottom. Anyplace else may force sealant into the valve. Also you should not need to tighten the nut on the stem anything more than hand tight. That is why it does not have edges for a wrench. If you could not get the stem out it was probably just twisting in the rim. If this is the issue just use two pairs of pliers to hold it in place.

    When removing the core there is no special tool, just some needle nose pliers to remove. I pull mine every time I up my sealant, or about every 2-3 months.

  15. #15
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    Quote Originally Posted by hoolie View Post
    Every time I park my bikes, I position the tubeless valve stems so that the sealant will hopefully run downward, back into the tires. This is not scientific, just my GUT feeling.
    Correct - not just a gut feeling.

  16. #16
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    Quote Originally Posted by Salespunk View Post
    When removing the core there is no special tool, just some needle nose pliers to remove. I pull mine every time I up my sealant, or about every 2-3 months.
    There is a tool... it looks like this:

    or this

    costs a few bucks, and if you ever use one you will not go back to needle nose.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  17. #17
    Nouveau Retrogrouch SuperModerator
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    Re: Stan's Clogging Valve cores

    Quote Originally Posted by meltingfeather View Post
    There is a tool... it looks like this:

    or this

    costs a few bucks, and if you ever use one you will not go back to needle nose.
    I prefer this type, which come with Mavic UST valves and some other brands, and can be found for next to nothing.
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