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Leaky Valve Stem - question

onelfastlride

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My tire has a slow leak. It appears to lose about 1 lb a week. I’ve removed the tire and there is nothing in it, no punctures. The tire and rim are as new as it gets.

If you look at the video, it appears to be leaking around the metal valve stem nut.

Before I have the tire dismounted, from the carbon fiber rim, to replace the tpms sensor assembly………

* Does anyone know how tight the nut that holds the valve stem in place gets torqued to?

I am curious if I tightened it up, could I get the o-ring at the base of the valve stem to seal. I do not want to over do it though.

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Inthehighdesert

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It’s not much. If memory serves right its around ten lbs. I’ve changed valve stems and tpms’s without removing the tire. I’ve gone up a size(thickness) on the orings in the past as well. You may just need to replace the oring. If you mark the tire and wheel for proper orientation it won’t change the balance. Obviously you can rebalance the wheel if you want.
 
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onelfastlride

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It’s not much. If memory serves right its around ten lbs. I’ve changed valve stems and tpms’s without removing the tire. I’ve gone up a size(thickness) on the orings in the past as well. You may just need to replace the oring. If you mark the tire and wheel for proper orientation it won’t change the balance. Obviously you can rebalance the wheel if you want.
Thanks for the information. The car has 6.9 miles on it at this point. I guess the good news is the tire has nothing in it.

I bought a new tpms assembly and I’ve found a few shops around that have a touchless Hunter Revolution tire mounting machine.

Side note: the Ford dealer near me has a Hunter Machine, but they don’t want to do it.
 

Inthehighdesert

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I’m assuming its under warranty, so that’s your call. Personally I’d take it to who is comfortable doing it. It’s such an inexpensive and quick repair but the liability is there for the shops so I get it with the hesitance.


Thanks for the information. The car has 6.9 miles on it at this point. I guess the good news is the tire has nothing in it.

I bought a new tpms assembly and I’ve found a few shops around that have a touchless Hunter Revolution tire mounting machine.

Side note: the Ford dealer near me has a Hunter Machine, but they don’t want to do it.
 
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onelfastlride

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I’m assuming its under warranty, so that’s your call. Personally I’d take it to who is comfortable doing it. It’s such an inexpensive and quick repair but the liability is there for the shops so I get it with the hesitance.
It is under warranty. It won’t be going to the local Ford dealer. I have a new TPMS sensor assembly and I’ll be taking it to one of the two places that I called with a Hunter Revolution tire mounting machine and were confident they could handle it without damaging the cf rim.

I just wanted to see if I could get the o-ring to seal up by tightening it down. With the weight off the wheel I may loosen it up, wiggle it a little, and retighten it. Worth a try before it’s replaced.
 

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Tomster

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I had a problem like this once. Unfortunately if the stem torque doesn't correct the problem the correct fix is to dismount the tire and replace the tpms rubber seals. They are not cheap, and its probably cost effective to just replace the entire tpms assembly. what I did to temporarily fix the problem was to take Teflon tape around the stem threads and stop the air leaking out. Its nothing that I would take on the track, but if you need to buy time until you can replace the tpms, then its probably worth doing.

If it was my wheel and it was under warranty, I'd let ford fix it. They have the hunter machine and they are on the hook to fix it.
 

Cobra Jet

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I had a problem like this once. Unfortunately if the stem torque doesn't correct the problem the correct fix is to dismount the tire and replace the tpms rubber seals. They are not cheap, and its probably cost effective to just replace the entire tpms assembly. what I did to temporarily fix the problem was to take Teflon tape around the stem threads and stop the air leaking out. Its nothing that I would take on the track, but if you need to buy time until you can replace the tpms, then its probably worth doing.

If it was my wheel and it was under warranty, I'd let ford fix it. They have the hunter machine and they are on the hook to fix it.
Not only is Ford on the hook to fix it under warranty, they would also be on the hook to replace the CF rim IF it were to be damaged.

That's the bigger consideration between getting Ford to do it under warranty, rather than some outside shop that "has a Hunter whatever machine".... Just because the other shop has the same machine as Ford doesn't mean their Tech is any better (or worse) than the Ford Tech, but you better read their fine print before signing anything and handing over your CF rim for repair. I say that because the question will be: If the outside shop F's up that CF rim, are they going to pay for the exorbitant cost of a new CF rim replacement? Probably most likely not....
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