Corroded Stem Caps


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Old 11-24-12, 04:06 PM
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Corroded Stem Caps

My wife's car has corroded tire air valve stem caps. So far, I've tried dousing them in WD40 and removing, but no luck. Normally we'd just cut them off, but of course they have TPMS sensors that would be about $400 to replace all of them.

So I'm looking for general ideas on getting the cap off without damaging the sensors. My only idea at this point would be to use a Dremel and carefully cut off the cap, or at least get it so I can pump something in there to fight the corrosion.

Ideas?
 
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Old 11-24-12, 04:27 PM
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Welcome to the forums! What are the caps made of? Have you tried a pair of pliers or wrench to extricate them? Never heard of plastic or stainless steel seizing up like that. Oh, yeah, WD40 is technically not a lubricant nor is it an antiseizing compund. It is a water displacement product. Use PB Blaster products for freeing up frozen nuts. They have several products, so you'll have to choose the right one for your application.
 
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Old 11-24-12, 05:34 PM
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silly may sound, but you sure do loosen them the right direction?
Just looked at my Camry, she has TPMS rims, and caps are simple g'ol plastic.
Take pictures. Something ain't right.
 
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Old 11-24-12, 05:40 PM
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Thanks for the warm welcome. Not sure what type of metal they are, but they're chrome. I have tried a couple hand tools including a wrench and a vice grip, no luck. Good point on the WD 40, I guess I knew that, but its all I have at the moment.

Looks like PB Blaster is the one I want, I'll pick some up and give it a go.
 
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Old 11-26-12, 04:50 PM
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Job Done

Thanks everyone for your help. I was able to get the caps off with some PB Blaster, a vice grip and wrench.

I attached some pictures of what I was dealing with. Basically metal caps that had bonded themselves with the air stems.
 
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Old 11-26-12, 05:02 PM
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Whoa, that's serious. I guess the new ones will have a dab of lube on it when you put them on, or use plastic ones.
 
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Old 11-26-12, 06:34 PM
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Yeah, no kidding, lesson learned. Don't use metal caps, or if you do, check them often.
 
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Old 11-26-12, 06:58 PM
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They must have been bi-metallic couple, resulting in galvanic currents, resulting in oxidation.
 
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Old 11-26-12, 06:59 PM
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Or they could have rusted on..........you learned too many big words, Igor!
 
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Old 11-26-12, 07:05 PM
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Well, they used to chrome atop of copper or brass blanks. Soft metals are easy to shape. As a result, you have copper and steel stem. Bimetallic couple. Why would rostfrei steel and another rostfrei steel cap rust together otherwise?
Yes, I actually had 11 chemistries back in life.
 
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Old 11-26-12, 07:07 PM
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Yeah I had some "pretty" parts on older hot rods that were chromed copper or bronze, which had galvanic reaction and froze solid. You know I was kidding, right??
 
 

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