[bethesdaForte]

The driver's side front tire on my 2019 Kia Forte FE with 16500 miles on it keeps loosing air. I took it to NTB and they pulled out a nail and patched it. The next day, the pressure went down from 32 psi to 20 psi. I took it back to NTB and they kept the car for a whole day. They couldn't figure out what was wrong. They dunked it in water and couldn't find any leaks. They checked the seal to the rim and it was fine. Any idea what is happening? I hope I don't have to replace the tire.

 

[joachimkazmaier]

Going by elimination:

• leak patched
• seal to rim checked
• no other leaks detected on tire

Right?

Have they checked the valve? If not, you can check that by yourself quite easily, either with your saliva or some water. You do not need to remove the wheel for that, but roll the car, so that the valve points upward, then put 40 psi, and with the dustcap removed, put water in the cavity of the valve. You'll see right away if it leaks. Another possibility, is that the valve stem is leaking air. For that, just grab the valve and wriggle it, with some force but not brute force. You would hear 'pfft' if the valve stem is shot. Imho, that's very early, unusual to have a leaking valve stem after 2 years, but nothing is impossible.

Good luck

 

[ForteSX2.4]

Use soapy water to check for leaks around the valve stem...window washer fluid works well. The soap will bubble up if there is a small leak. Check it with the cap removed. ...and don't forget to check the valve stem cap - if the rubber seal is missing OR twisted the cap can caused the valve to be depressed - had that happen before.

 

[joachimkazmaier]

Use soapy water to check for leaks around the valve stem...window washer fluid works well. The soap will bubble up if there is a small leak. Check it with the cap removed. ...and don't forget to check the valve stem cap - if the rubber seal is missing OR twisted the cap can caused the valve to be depressed - had that happen before.

That would actually be my guess, that the valve core is a bit bent and does not fully return and is leaking there. Easy fix, @bethesdaForte, buy the valve core and the key to remove it. Combined probably around $5.Plus pumping the air back

 

[ForteSX2.4]

I put some of those "Kia" valve stem caps on my daughters Koup years ago and one of her tires kept going low. Every time I checked the tire with soapy water NOTHING showed up (of course, I was taking OFF the cap off to check for leaks). FINALLY I looked in the stupid "Kia" cap and saw that it had a center casting flash in it that was pushing the stem in when you screwed it on. Talk about "driving" people crazy looking for a leak!!!