Weird tire thing going on. Front left and right rear have needed air every 6 months or so. Of course wife taking 4 friends in the 2017 gmc acadia limited tomorrow. Tpms came on for front left tire. Small air compressor, pumped it up to 38,and watched as the gauge went down to 32 and it stayed there. 3 hours later front left down to 30 and right rear pumped up to 38 down to 32. Senoir safety got an appt at 10.30 am at the dealer, hoping just bad bead seal. 44k on tires and good tread, no obvious damage or punctures. urrent readings from car info which have been been accurate so far.
Take the tire off and spray soap on it. You’ll see the air leakage right away. Or, dip the tire in large bucket and keep rotating it until you can see the leak under the water.
With very slow leaks I’ve sprayed with soapy water and couldn’t find the leak. But after I wait 10 minutes after spraying, the leak is obvious.
I don’t think this is a leak. I think it’s a faulty sensor - perhaps even a faulty valve.
It ended up being 2 bad valve stems.
The dash readings are reliable. It was the pump gauge watching the pressure drop on the front tire maybe over 30 seconds from 38psi and stop at 32. It was 30psi in the am.
Did not want to take any chances as wife going on road trip this aft. It was too odd of an event not to worry.
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So it was the valve stems themselves, with or without the sensor, or the valve core?
It was a kit. 2005-2023 GM Tire Pressure Sensor Kit with Bolt, Valve Cap, and Valve Stem 13598909 | GM Parts Center
Two valve stem leaks on the same car? hmmm … 55+ years of driving, never had a bad valve stem. Curious to wonder why you had two? Hopefully the manufacturer just had a batch of bad valve stems the day those tires were built at the factory. I’ve seen that sort of problem in the tech-world before, an entire batch of faulty fuses.
I’ve had leaking tires of course, but the type you describe were all at the rim/tire interface.
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You just don’t drive enough. Very hard to find the leak on a stem. Soapy water doesn’t do it for a slow leak. On one I had to submerge the tire and after about five minutes a bubble came out of around the stem. Because they stick out they can take some abuse too.
I can see that could happen pretty easily, but I think the OP’s leaks were from the end of the valve stem, valve core/seat problem. Seems hard to understand there could be two on the same fairly new car.
I had a bade valve core once and replacing it solved the problem.
Stuff happens George.
Say the odds of it happening once were 1 in 1000. Rare, but not unheard of. One in a million to happen twice. Ed McMahon magazine sweepstakes chances.
I think I asked if it was valve core but the whole kit was replaced. So could have been leak around the seal in the wheel, damaged stem, valve core, but we just don’t know from Barkys answer. I bought more valve cores anyway. Wasted a couple looking for the leak in my inner tube.
I’ve seen bad valve stems. They’re only a piece of rubber and metal subject to horrendous environmental conditions, spinning around at how many revolutions per minute on the ground in all kinds of weather with who knows what all around. It’s a wonder that they don’t break more often.
The rubber valve stem is a special built valve stem that has a provision for a TPMS sensor to be mounted to the end of it, with the weight of the sensor at speed plus bumps in the road etc etc etc, they tend to bend/flex a little and over time will/can cause them to leak at the wheel…
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Is it generally accepted by car repair folks that the tpms-equipped valve stems are more prone to leaking air than the no-sensor version? If so, sort of ironic, sure, with tpms you can more easily monitor the tire pressure, but it is more likely to go down … lol …
I think it is more accepted that pros just know that checking the valve stem however it is made and attached to the wheel, that it is part of the check when looking for a leak…