Bike Forums - Presta core non-sealing issue

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Presta core non-sealing issue

My new aluminum valves that I am using for my road tubeless wheels are leaky.

i seem to have tightened the rubber “cone” suuficiently but I took the inner core out & put it back in a few times in the course of trying to get a blast of air to seat the bead on the rim.

so far, so good - I finally seem to have been successful with that but the Presta core is now stuck open.

Is is there a way to coax this sticky valve to close properly under pressure?

Tried another valve stem in the place of the leaking one yet? get it to work , 1st, then you can ponder why at your leisure ..

...

What are you using for sealant? Look at the threads of your core for dried sealant, Could be that its preventing the core from fully sealing.

Quote:

Originally Posted by fietsbob (Post 20718713)

Tried another valve stem in the place of the leaking one yet? get it to work , 1st, then you can ponder why at your leisure ..

...

turns out I pinched the aluminum presta core when it got stuck in the threaded Airshot hose. I pulled another presta core from a blown latex tube I had laying around and now it is sealing.

Quote:

Originally Posted by DOS (Post 20719012)

What are you using for sealant? Look at the threads of your core for dried sealant, Could be that its preventing the core from fully sealing.

I’ve never introduced any sealant yet. I never got that far. My objective has been to just do the initial mounting of the tubeless tire onto the tubeless rim and see that the bead is all the way on the shelf on both rim sides and beginning to hold air. I’m now at that point. It does hold air for a few minutes. So I guess now I will pump it up to about 90 or 100 (yet again), pull the presta core (again), introduce 60ml of Stan’s sealant, re-insert the presta core, reinflate and then check for leaks and spin wheel to distribute the sealant.

All this his trial and error has been much busier than normal bike maintenance jobs. At least it is the winter and I’m not missing too much choice riding weather.

Quote:

Originally Posted by masi61 (Post 20719731)

If the bead is seated, no need to pump up again.Just pull the core and add sealant.Then replace the core,spin the tire and pump. If the tire isn’t fully seated, dont insert the core.Pump the tire up without the core so yo are getting as much air into the tire as quicly as possible. If its holding air with the pump head attached to the stem, you should good to go. Then you just remove the head to let the air out so you can add sealant. Generally its a good idea install the core only after you have gotten the bead to seat both because you get air into the tire more rapidly and it reduces chance you will damage the core.

Quote:

Originally Posted by DOS (Post 20720145)

Thanks for your help. All this core in, core out confusion by me is because up until this point I had been unsuccessful. Thanks to the Airshot and my old trusty Zefal Husky floor pump, I think I’m finally understanding the workflow to be successful without so much trial and error. The Airshot has a little thread in connector that fits in the Presta valve minus the core. This set-up did indeed seem to let more air in, quicker the result being that I could hear more definitive popping as the bead was snapping onto the rim shelf around the full perimeter.

Today I plan to do the final step and add the Stan’s sealant. Yesterday I held off on adding sealant as I tested to see if the tire held air for any amount of time sans sealant. It really didn’t - it went from 81 psi down to 30 psi in 3 hours.