Tubeless leak around valve stem. Would sealant likely fix?

[makoti]

Had a set of wheels that worked well, until the front developed a braking issue I think was due to sealant build up. Went ahead and replaced the tire, since it had a lot of miles on it. Switched to a Fillmore valve.
Well, I couldn't get a seal around the valve. Tried several times (NO SEALANT YET), retaped twice, same problem.
So I switched valves to something else, an American Classic I had laying around, retaped again. Same, though not as pronounced, problem. Still leaks from the base of the valve, but not gushing out. I haven't put back in the old valve yet, thinking new would be better, but I guess that will be the next step.
Question is: This is without sealant. Would sealant seal this up? I've never had this issue before. Leaks, but never the valve. Sealant would take care of most of those. Any thoughts as to why the rim suddenly won't seal the valve?

[nmrt]

I have had this same issue with....American Classic valves. Most times sealant did fix it. But a few times, I had to retape which solved the problem.

I am not sure why the retaping has not solved the issue. Perhaps it has to do with the interface between the valve and the rim bed. Some (not American Classic) valves come with a few different rim "inserts" to fit different rim shapes. Maybe try using those type of tubeless valves?

Originally Posted by makoti

Had a set of wheels that worked well, until the front developed a braking issue I think was due to sealant build up. Went ahead and replaced the tire, since it had a lot of miles on it. Switched to a Fillmore valve.
Well, I couldn't get a seal around the valve. Tried several times (NO SEALANT YET), retaped twice, same problem.
So I switched valves to something else, an American Classic I had laying around, retaped again. Same, though not as pronounced, problem. Still leaks from the base of the valve, but not gushing out. I haven't put back in the old valve yet, thinking new would be better, but I guess that will be the next step.
Question is: This is without sealant. Would sealant seal this up? I've never had this issue before. Leaks, but never the valve. Sealant would take care of most of those. Any thoughts as to why the rim suddenly won't seal the valve?

[.RJ]

You likely have a leak somewhere else under the tape (and through the rim cavity) thats coming out of the valve hole, as thats the path of least resistance.

[AngryScientist]

Couple points:

1) Once you put sealant in the tire, everything gets more difficult. You've got a mess on your hands if you still need to tinker with the valve or the tape once the sealant is involved. You want the best chance of success before the final step of adding sealant.

2) Some valves (the phot below is just an example) come with different rubber blocks to seal the valve stem that are changeable to best suit the rim bed. Perhaps you need a different shape block to get the best seal?

I have never had a case where the valve stem could not get a good tight seal with the right interface there.

[wtex]

I'd also look at a valve that uses the small o-ring that installs against the external, bottom wall of the rim, and that then gets pressed against the rim as you tighten the valve nut. That could be the difference.

[old fat man]

Originally Posted by .RJ

You likely have a leak somewhere else under the tape (and through the rim cavity) thats coming out of the valve hole, as thats the path of least resistance.

This. More likely that you have a leak elsewhere. A better fitting valve may make up for the leak but you should consider replacing the tape, or installing a tire with a tube to make sure the tape is firmly pressed/sealed and then go back to the tubeless setup.

Also, how does sealant buildup cause a braking problem?

[HenryA]

Originally Posted by wtex

I'd also look at a valve that uses the small o-ring that installs against the external, bottom wall of the rim, and that then gets pressed against the rim as you tighten the valve nut. That could be the difference.

^^^^^^^^^^^^this

On edit, I did a poor job of reading the post. It is the o ring or other shaped rubber that seals on the inside.

[MikeD]

Originally Posted by wtex

I'd also look at a valve that uses the small o-ring that installs against the external, bottom wall of the rim, and that then gets pressed against the rim as you tighten the valve nut. That could be the difference.

The purpose of that o ring is not to provide a seal.

[AngryScientist]

Originally Posted by MikeD

The purpose of that o ring is not to provide a seal.

Correct. If that o-ring were a sealing surface, that would mean you pressurized the rim cavity, which is a big no-no. The seal has to occur at the rim bed interface.

That o-ring merely prevents metal (or carbon) to metal contact at the valve nut and also keeps moisture from entering the rim cavity along the valve stem. Nothing to do with pressure retention.

[ColonelJLloyd]

Originally Posted by old fat man

also, how does sealant buildup cause a braking problem?

+1

[makoti]

Originally Posted by nmrt

I have had this same issue with....American Classic valves. Most times sealant did fix it. But a few times, I had to retape which solved the problem.

I am not sure why the retaping has not solved the issue. Perhaps it has to do with the interface between the valve and the rim bed. Some (not American Classic) valves come with a few different rim "inserts" to fit different rim shapes. Maybe try using those type of tubeless valves?

But in my case, it's two different brands. The Fillmore was much worse, too

[makoti]

Originally Posted by old fat man

Also, how does sealant buildup cause a braking problem?

It was a wad of sealant. When you pressed the deflated tire at that spot, it was firm. If you spun the wheel off the bike, it had a noticeable hop to it. I can only guess it threw off the rotating mass of the wheel, and the brakes chattered.
That's the theory. I can't get the wheel to hold air to test it out

[.RJ]

Originally Posted by wtex

I'd also look at a valve that uses the small o-ring that installs against the external, bottom wall of the rim, and that then gets pressed against the rim as you tighten the valve nut. That could be the difference.

No, this does not help anything seal.

I just had this situation myself on Friday - mounting up a new set of race kings (PSA, with the new 'e-bike' designation on the tires conti have tightened up the beads) that were too tight with 2 layers of tape and I had pushed the tape off the bead mounting the tire. But it wasnt obvious as pulling the tire off allowed the tape to slide back to its original spot. Only after mounting and removing the tire 3 times did it become obvious what was happening.

[jamesdak]

Dealt with my first set of tubeless tires today sorting out a Dura Ace WH-7850 wheelset. Such a mess to "solve" a problem I don't have is the conclusion I came too. Maybe if I flatted more than once or twice a year I'd consider dealing with it. Pulled those tires off, cleaned up the mess, and mounted proper tires and tubes.

[makoti]

Originally Posted by jamesdak

Dealt with my first set of tubeless tires today sorting out a Dura Ace WH-7850 wheelset. Such a mess to "solve" a problem I don't have is the conclusion I came too. Maybe if I flatted more than once or twice a year I'd consider dealing with it. Pulled those tires off, cleaned up the mess, and mounted proper tires and tubes.

Thanks. That's helpful.
I rode today on a brand new tire. A mile from home, hit something, maybe a rock under leaves. Puncture, but no flat. Able to ride home without stopping.
See? That doesn't have anything to do with the post, either.