Billy1111

Hi

I have been running Mavic Comete tubeless for the past few weeks...after a short tweaking of the PSI everything has been great with them.

Today I put some air into the rear then when i tried to put some air in the front sealant started spraying out of the valve.

i rolled the the tire to put the valve at the top and and tried to put air in again and same thing happened! i left the tire as it was and road with no issues

this never happened before filling the tire with air...any idea wtf is going on??

Seattle Forrest

It got into the valve. Happens occasionally. Did you set them up, or the shop?

Billy1111

I did!

chaadster

I take it you mean that you tapped the valve in preparation to attach the pump, and that's when it sprayed sealant? If so, yeah, as @seattle_Forrest said, there was probably sealant in the valve stem.

To avoid this, clear sealant from the stem by giving the wheel a good spin before airing it up, or at least keep the valve somewhere in the lower half of the wheel, like betwee 4 and 8 o'clock, so that sealant drains out of the valve stem.

Seattle Forrest

This has happened to me a few times but I had the shop set them up, so I took them back and they took care of it for me. I think you're going to have to pull the valve out, and I don't know if they can be cleaned or just replaced.

beanbag

I agree with this

Billy1111

thanx guys!

chaadster

I'd just try pumping it up normally; if it sticks and doesn't close, well, then you fix it. If that's the case, just unscrew the core and rub off any sealant on the o-ring at the bottom. The stem pin should toggle up and down freely. It's a very simply device, so I can't imagine what kind of problem could be had, but if the pin isn't free, or pumping is difficult, I suppose there could be solid sealant in the core, in which case I'd just rinse it with hot water, dry, and reinstall.

JohnJ80

^^ this. Learn how to do this.

I've been running sealant in tubeless tires (tubular mostly) for about 10 years now. Very useful to make sure you have a tool to remove cores so you can clean them like this. Also, you can buy valve cores pretty cheaply ($5 for 10 or so) and it pays to have some on hand. At some point, they do get hard to clean out.

But here's the head slapping simple stupid trick I learned this year. When you put your bike away for any length of time, make sure the valves are at the BOTTOM of the wheel (or on the down side of the wheel depending on how you store your bike). Doing this allows the any sealant that may have pooled in the stem to drain out and stay out of the valve. Doing this, you'll have a lot less problems. Sure worked for me and it irritates me I didn't think of it because it's that simple.

Another thing worth looking at are the MilkIt stems. This is kind of interesting because this stem allows you to actually remove the sealant from your tire, check it, see how much is in there etc... But more interestingly, it's got a little flap on the bottom of the stem that actually stops sealant from getting to the valve. Downside is that their valves are proprietary because they have a little piece that fits on the bottom of the valve that pushes the flapper open to allow air out. Regular presta stems will work but it's harder to let air out - not such a big deal for road tires but can be more of an issue for, say, fat bike tires. Either way, you won't get stranded and it pretty much ends the junk-in-the-valve problem.

J.