Tire Valve Core - Montana Owners Club

**scottz** · 04-30-2021, 01:10 AM

Are all tire valve cores the same? I have an interesting problem. Went to the shop today and found one of my tires flat. This is the same tire that I replaced the valve core in a while back. The reason the valve core was replaced? After adding air, it would not spring into the closed position. So, today I added air using my Milton inflator; got it up to 110psi, pulled the inflator off and same problem. This is the second valve core to do it. Ok, I put a third new valve core in; same thing. Now I'm starting to suspect the Milton inflator is somehow damaging the valve cores so I used a different air chuck; same results with third core; will not seal. A little experimentation found that if I unscrewed the valve core a few turns, it would pop closed. Then I could tighten it back up and it would hold. That is the condition now; I'll check for a flat in the morning but not hopeful.

I cannot swear to it (blaming it on old age memory loss), but I think I had a similar issue on a different tire, but only replaced the valve core once and all is well.

So here is the question. Are all valve cores equal? Maybe I have some junk and need to look for better ones. I did a Google search and did not find much.

I just had another thought; I use the 507 TPMS with cap style (not flow through) sensors. When these are on, the valve core is continuously held open. Could this be causing an issue? I don't really think so, because a lot of people use this system and I have never heard of a problem. I don't leave the sensors on all year; I take them off for the winter.

I guess my next step is to try to find some high quality valve cores or replace the valve stem on that wheel.

Anyone else experienced this? Suggestions?

RMcNeal · 04-30-2021, 04:17 AM

I have the EEZRV TPMS with similar sensors to what you have with the TST. I leave them on all year with no issues. I only remove them to add air when needed. My guess is the core you are using may be off spec a bit. If you can back off a little and get it to seal, then the spring may be weak or not seated correctly, etc. I don't think it is being caused by the TPMS sensors though. I'd look into getting new cores and see if that fixes the problem.

Montana Man · 04-30-2021, 07:05 AM

At this point I would replace the whole stem assembly.

JandC · 04-30-2021, 08:22 AM

I had a stem fail last year while on the road. My TST system alerted me and I was able to get off the road and change the tire out. My valve stems were less than two years old and even though we are full timers I take my button sensors off if I am stationary for 2 weeks or longer.

**scottz** · 05-05-2021, 09:30 PM

Update. I pulled the old old valve core (#3) out of the trash and see why it was leaking, but no idea what caused the damage. See photo #1.

Since the one I had in there (left rear tire) had stuck once, I did not trust it and replaced it. I pulled the core out and found the orange extension cap on the valve core; see photo #2 (top). Now, this is where it starts to get weird. I am 100% sure that cap was not on the core I installed a couple days ago. The one I installed was like photo #2 bottom; got a whole pack of them. Thinking senility was setting in, I figured I must have worked on the front left not the rear left. Pulled the core out of the front tire; also has a cap on it. I'm not so far gone that I could be on the wrong side of the 5th wheel.

So, two questions:

1. What is that cap on the end of the valve core?

2. Which one of you guys got into my shop and changed it?

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