Road tubeless valves gunked up with sealant

I have started running a tubeless set-up for my carbon rims and found that whenever I need to pump up the tyres, the valve is stuck and wont undo due to being clogged with sealant. I end up having to take the valve core out and open and close the valve a few times to loosen it off, and then it is fine.

Is this a common problem? or a sign that I have to much sealant in the wheels?

I do get some gunk occasionally on the valves on my gravel bike but they seem to loosen up. I have not had to remove the valve core.

Can happen in many setups. Sealant level may influence it
Also, I try to only inflate when the valve stem is on the top half of the wheel. I seem to get more contamination if I fill with the stem low.


I use regular Stan’s sealant.

Couple things that I have found to help;

-When you put sealant in tire remove the valve core if you fill through the valve, or put sealant in before you fully mount the tire

-When you pump up or let pressure out of the tire never do this in the 6 0’clock position

-Sometimes you have to remove the valve core and clean out the gunk, or just replace the core.

It happens. Like others have said, to minimize gunk accumulation going forward, rotate to 3 or 9 o’clock position, wait if possible, let some air out with your finger, then add air.

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Just buy a 10 pack of valve cores and swap them out when they gunk up

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In addition to the other tips, a straight pick or tooth pick if your valve isn’t too long can easily unclog a valve tube once you have the core unscrewed.


I prepped my MTB today for the upcoming season. One of the things I do is redo the tubeless tires - remove the tires, clean them out, check rim tape, add new sealant, etc.

I also check the valve cores for dried sealant. I’ve found that WD40 and a pin allows me to clean out the dried sealant stuck in the valve core. Restores the valve cores to almost like new.

Course you could also buy a new valve core, but that’s cheating :grin:

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