Valve stem core stuck open, TPMS?

[cvdell]

Since getting new tires a month ago, I've had 3 instances of a valve stem core being stuck open after I remove the TPMS cap (TST TPMS). I checked the core, it was tight. Removed core and put back in, didn't fix problem. Tire continued rapid deflation. Cores are red band, without filter (no balancing beads were installed, filter shouldnt be needed).

Changing to a new core, which the tire shop did, "fixed" the problem. I now carry a dozen spare cores in case this happens again.

Tire shop (Pete's Road Service) said the TPMS cap might have been on too tight, pushing down too hard, causing the core to be stuck open after cap is removed. Don't buy that idea - problem started w new tire install. Plus, I screw TPMS caps on only right enough to create a seal.

Anyone had this issue? Have a root cause?

[richard5933]

I've had TPMS on our coach for a few years now. The sensors are removed a few times a year to confirm pressures, and they are totally removed before storing for winter. Have had the tires changed out once during this time.

Never have had any problem with a valve stem sticking open.

I'm wondering if they didn't get something on the inside of the valve when installed them - possibly something was in the soapy water that's used to lubricate the rubber as it's pulled through or when the tire is seated?

My first attempt at solving this would be to have the valve stem pointing strait down and then pulling the core out. Hopefully whatever might be inside the tire will find its way out the open core. Don't let the tire go flat - just let 10-15psi out to flush out the valve stem.

There is a tool which can be used to re-seat the seat inside the valve stem so that the valve can seal against it better. Shouldn't be needed on brand-new valve stems, but maybe the batch you have aren't made.

 

If it

[campcop]

If you’ve ever watched a tire shop change tires, you’ll probably notice that the tech just throws the valves and caps on a work station. If he uses the same ones is anyone’s guess.

I have stainless steel caps in my vehicles , if I have the wheels rotated at a dealer, I remove the caps. Most times when I get the vehicle, back I find cheapy plastic valve caps on the wheels.

Edited October 28, 2020 by campcop

[rayin]

34 minutes ago, campcop said:

If you’ve ever watched a tire shop change tires, you’ll probably notice that the tech just throws the valves and caps on a work station. If he uses the same ones is anyone’s guess.

I have stainless steel caps in my vehicles , if I have the wheels rotated at a dealer, I remove the caps. Most times when I get the vehicle, back I find cheapy plastic valve caps on the wheels.

Yes, the plastic ones are merely dust caps, metal ones are designed to hold truck tire air pressure if the valve core fails. I have witnessed tire changers throw used cores on the same table with new ones.

[tireman9]

I have a number of posts on valves and valve cores in my blog. Too much to re-post here. BUT

 

Yes valve cores can stick open and it may be possible the TPMS holding the core open may have contributed to this issue. Just get some new cores at any auto parts store.

Don't over-tighten. Read this post on how tight is tight enough. 3/4 turn after air leak stops.  Use a metal valve cap with an internal gasket if not running your TPMS.

[cvdell]

Thanks for the feedback, think I've figured out what happened. Turns out they did use balancing beads (I don't remember any discussion on that subject, didnt notice that line on the receipt). The problem is they didnt use the special "filtered" cores, so dust/particles from the beads can get in onto the core(s) and hold them open. Have now swapped out out cores for filtered ones, all ok so far.

[cvdell]

On 11/11/2020 at 3:10 PM, tireman9 said:

I have a number of posts on valves and valve cores in my blog. Too much to re-post here. BUT

 

Yes valve cores can stick open and it may be possible the TPMS holding the core open may have contributed to this issue. Just get some new cores at any auto parts store.

Don't over-tighten. Read this post on how tight is tight enough. 3/4 turn after air leak stops.  Use a metal valve cap with an internal gasket if not running your TPMS.

Good information, thank you. Btw - don't think I was over tightening the cores. I pull cores regularly to air down/up the jeep when going off road. Treat RV cores same way (but hopefully not as frequently).

[tireman9]

If something gets in the core the only "fix" is to replace the core itself. There is no opening between the stem and core like n a water faucet so drying to clear the dust by removing the core will not work.

Re over tightening the core. Spec is 2 to 5 in-Oz.   I just tested a neat tool from SLIME.

A Torque limiting tool.

$5 at Autozone.

I tested it and it "clicks" and releases at 3.5 in-oz. Will be posting on my blog soon as a tool I "Endorse".