I'm losing air in a tire. I went to fill it but couldn't get the valve stem cap off. The guy who was there tried to remove it with a wrench. Are these caps locked on in any manner? I'm in a 20177 F-Type.

 

They're not locked. My guess is it is an aftermarket aluminum or metal cap (or plastic cap with metal threads) that hasn't be removed in a while. The dissimilar metals can corrode and the threads fuse together. Honda had a big issue with that years ago and stopped using metal threads on the caps. I would think rotating with a pair of pliers should be able to get it off (although you will probably destroy the cap), or you could try heating it. Worst case scenario is a tire shop can just replace the whole valve stem.

 

Great. Thank you, Thunder Dump. I didn't want to start going at it to find out there was some special way to remove it, like pushing it in, etc.

Will get back out there with a wrench. The pressure has been going down, but very slowly. Maybe there's a nail hiding somewhere.

 

Mix some dish soap & water into a small spray bottle, and spray the valve stem. Any leaks will result in beautiful bubbles.

If that is OK, remove the wheel/tire and inspect it for signs of damage. The soapy water can point out issues with any possible damage (cuts).

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Regards the valve stem cap: apply some penetrating oil first.

I've had tire shops leave the fill valve inside, loose.

 

Thank you! Was able to get it removed. Now we'll see if it holds the air.

 

I had tire leakage issue, turned out the core had loosened. A quick tighten resolved it.
diagram

https://www.discounttire.com/learn/valve-stems

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