If the base of the valve isn't round, since it's rotated it may no longer be seated in the channel of the rim.

 

I didn't turn it that far, I don't believe. They're black and shorter, but have a similar nut on them. The "overtorquing" was a bit of a joke because you can't generate much torque with one of those little "wrenches," but I did try to tighten it pretty good and may have slightly turned the stem, enough to break any sealant seal, possibly, not enough to turn it out of the channel if of that configuration,

 

You can get like 100 brand new presta valve cores on Amazon for like $2.
=sParty

 

This sounds like the good ole days when I used to spend fleabay bucks on cores and pretty anodized caps. Best I can find now is $8 for 20 and similar on fleabay. Any linkages?

 

what sealant?

I ditched orange seal because the big honking glitter shards kept getting jammed in my valves and tearing up the rubber seal on the core.

and yeah, buy a big supply of spare cores for cheap, and put a few in every spot you might need 'em.

 

I'm not sure what it came with (new in March), but I have put two "rounds" of Stans in it since. Due for a third and I have Orange Seal on order.😁

 

It also might be because your rim tape is old and it doesn't hold on well anymore, or it slid somewhere, and/or the Spoke nipple hole is exposed. That happened to my dad's bike, Spent 6 hours trying to put the tire on (not joking), and then eventually, I found out.

 

I got in a high speed wreck this year after my tire went flat on a downhill run, and I didn't realize it until ripping around a turn and folding over. The culprit was the little o-ring or whatever it is is at the base of the valve core. It had a tiny crack in it. I had just installed that valve core that morning and didn't realize it wasn't any good until it was too late. The tire would seem to hold air, then all of the sudden it'd be flat. I seemed to discover this at the worst time, like in turns or leaving the lip of a jump. Thankfully, I only crashed the one time before packing it in.

I've also had a valve stem crack. A chunk at the very top actually fell out, but it held air fine when everything was tightened down. I almost always carry a replacement valve core and will take a spare valve stem with me on bigger trips.

If I were you, I'd start by replacing the valve core and move from there.

 

Yeah, this had occurred to me. That little seal may not be any good, cracked, cross-linked, whatever.

I suspected that the cores may be leaky because the nuts have stuck on them front and rear, indicating that some sealant may be leaking up through it and "gluing" the nut. They don't clog in any conventional way, are visibly clean when removed, and I never had problems airing the tires, but the durned nuts would stick.

So, new cores and get that sealant refreshed. Thanks folks!

 

It is time to refresh the sealant, but I don't know the condition/haven't looked.

This is the obvious answer. Check conditions and refresh your sealant.

 

I'm a firm believer in the dust covers no-one uses and is seen as uncool to use.
In my sample of 1, the valve cores last longer before getting blocked when they aren't getting filled with dirt all the time, which combined with the sealant causes everything to clog up quicker. Although, I also just bought a 10 pack of valve cores and replace as often as needed.

 

My buddy refuses to use valve caps and it bothers me!

OP - I had this happen once after screwing in the valve core. Doing that loosened the the lock nut. Really annoying getting to the trail with no air in the tire. I had to tighten the lock ring/nut to seal the valve on the inside.

 

Any questionable core gets discarded ASAP by me. I don't even entertain cleaning it or anything. Just put a new one in and go from there.

 

Caps stopped their multiplication when I started running tubeless. I can honestly say I've never seen a core stem get bent like that! Outrageously 'lucky'!

 

Well, this morning I used the last couple of ounces of Stans in the tire, but couldn't find my cores. Aired it up and it leaked very slowly from 20 down to something close to nothing.

So, picked up some cores this afternoon and replaced and aired up again. We shall see.

The allegedly leaky core below and an example of the replacement cores above.

It appears that the seal in the lower, leaky one is a bit less "robust" than those on the uppers.

 

Like, cool, Bro!

 

If I were to suspect a valve core of leaking, I might just spray it with soapy water.

 

^^^ This. Soapy water is very useful. I use it to lubricate the bead when seating the tire, and if there are any leaks on the rim/tire interface you'll know. I have also started to put all my tubeless under water after I set the bead the first time with a new valve or tape set up. You'll see bubbles from the valve steam if it's the core or from the base of the stem if it's the stem/rim interface leaking. This way you'll know what to address.

 

Years ago, one of my friends bought a brand new GF Rumblefish and was taking his first ever mtb ride with us. He needed air in one of his tires so I unscrewed the dust cover off the Presta valve and tossed it over my shoulder without even thinking. His reaction was priceless.

 

Well, crap. It didn't hold air overnight. Back to the drawing board. Nothing happened that should have disturbed the tape, except maybe the slight twisting of the valve stem, but I would think that did not much more than break any sealant seal around it.

My only other guess at this point is the bead is leaking, so I may need to overpump. Thankfully, the sealant is out for delivery, so I can fill that up. I may need to do some soapy water immersion or spraying.. Dammit.

Which brings to mind another issue. In the past, I have refreshed, about every 90 days, with a small Stan's bottle of sealant and that's about 2 oz. I see that Orange Seal recommends 4 oz. And now I have the recurrent issue of mixing Stans and OS. I had satisfied myself that refreshing a tire with OS would be ok, now I may be looking at adding OS to fresh Stans. 😬😬

 

Well, crap. It didn't hold air overnight. Back to the drawing board. Nothing happened that should have disturbed the tape, except maybe the slight twisting of the valve stem, but I would think that did not much more than break any sealant seal around it.

My only other guess at this point is the bead is leaking, so I may need to overpump. Thankfully, the sealant is out for delivery, so I can fill that up. I may need to do some soapy water immersion or spraying.. Dammit.

Which brings to mind another issue. In the past, I have refreshed, about every 90 days, with a small Stan's bottle of sealant and that's about 2 oz. I see that Orange Seal recommends 4 oz.

How much sealant is in the tire now?

 

Ever since I started using Problem Solvers Big P Nuts and Super P Nuts on my stems, I've had zero problems with my stems sealing. Just sayin'.

 

I use those things, too.
=sParty

 

Water emersion or soapy water, bubbles will tell you where the leak is, then fix that. Also be sure to ride the bike with the new sealant in. Doesn't need to be far, maybe a half mile or so. IME that seems to help the sealant do its job.

Sorry for the repeat.

 

Well the higher pressure and bouncing it around made it hold pressure for two hours, so I rode for 8 miles this afternoon.

So, I'm guessing that my turning of the valve stem, slight as it was, probably unsealed it and lack of fluid sealant kept it from sealing back up. Or maybe just going flat disturbed enough things that the lack of sealant couldn't "fix."

Anyway, all seems well now. Thanks again for all the input.

One moral of the story seems to be the importance of refreshing sealant. I'm just a few weeks past 90 days in cool/cold weather, but here I am having tubeless problems.