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I'm new to tubeless tires. I have a road bike with 700/26 tires. I am refreshing the sealant in my tires. I removed the valve core no problem. I am using a syringe and loaded it up with 2 oz. of sealant. When I insert the plastic hose into the tire it goes in about and inch or so - it looks like the length of the valve.

When I plunge the syringe to insert the sealant, it backs up to the top of the valve and takes a while to drain into the tire. If I squeeze the tire a little bit it blows a bubble out the top of the valve and makes a mess on the floor. I'm not getting 2 oz. of sealant on the floor, so it seems to be getting into the tire but it takes it's time.

Is this normal? Does it normally take about 10 minutes to slowly inject 2 oz. of sealant? This happens in both front and rear tires. The bike and the tires are brand new from a dealer. Should the injector hose only go in about an inch? I would expect it to go into the tire, so maybe 1.5" or more.

Thanks for any advice. I just didn't know what to expect.

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    It doesn't sound like this your problem, but worth pointing out just in case that it's helpful to ensure the wheel is rotated so the valve isn't right at the bottom, as depending on how much sealant you're adding, the tyre volume can fill up to the valve level and overflow. For a typical dose into a 25mm road tyre I find turning the valve to about the 8- or 4-o'clock positions ensures the sealant flows nicely into the tyre.
    – BigglesZX
    Commented May 13 at 14:29

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That is not normal. You should be able to put the syringe fully through the valve stem and into the interior of the tire.

You have something blocking the inside of the valve stem, and it is most likely some solidified sealant. You can try to push the syringe through the built up sealant to clear the blockage. You can also use something else. I have a "sealant level dipstick" (a thin, plastic stick) that came with some sealant that I use. After removing the valve, I can assess how much sealant I have in my tire by putting the dipstick into the valve stem and drawing it back out, revealing my sealant level just like a dipstick used to check the oil level on an automobile engine. Using something like this that is durable enough and stiff enough to push it through the plug.

Once this is cleared, your sealant should flow through the valve stem and into the tire.

Note, it is fairly common for a bubble or two of sealant to pop back out after filling, but just a little bit.

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    I use a 1.5 or 2mm hex wrench (long side of an Allen key) to open up a blocked stem. It can work to infuse some air too. I like using a hand pump so I can push air quick and hard. A drop or two of lubricating penetrating oil can help prevent a clot within the stem, but I've found the opening at the end of the rubber seal is where the blockage usually forms.
    – Jeff
    Commented May 12 at 19:57

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