Caution-Frozen Valve Stem Caps
Thread Starter
Super Member
Joined: Oct 2007
Posts: 917
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From: Manassas, VA
10 Cayenne GTS, 07 Porsche 911 Turbo
Caution-Frozen Valve Stem Caps
Yesterday I wanted to check the tire pressure on my wife's BMW X3 that came with a tire pressure monitoring system (TPMS). When I tried to unscrew the first metal BMW valve stem cap it was frozen and the rest were the same. I couldn't even get it off with a pliar and may have stripped the head. So I called the dealer this morning and they said you should not put metal valve stem caps on a car with TPMS because they will freeze/rust in place. Trust me, it's TRUE! You should only use plastic or rubber valve stem caps. I also have AMG metal caps on my SL (my BS does not have TPMS) which explains why they are so difficult to unscrew. Just a heads up to avoid a future and potentially expensive problem.
Last edited by LOVEMYBS; Mar 29, 2010 at 12:24 PM. Reason: spelling
Member
Joined: Dec 2009
Posts: 156
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From: Redondo Beach, CA
2008 MBZ CLK63 AMG Black Series
But they dont make AMG caps in plastic, so how else am I supposed to bling my car?!
Seriously though, thanks for the FYI, and my solution to this issue is to use a little lithium grease on the metal caps, they won't freeze if you do that.
Seriously though, thanks for the FYI, and my solution to this issue is to use a little lithium grease on the metal caps, they won't freeze if you do that.
Senior Member
Joined: Jan 2009
Posts: 327
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From: Isla Verde, Puerto Rico
SRT-6
I've heard of this happening but it's never happened to me. I guess taking the caps off and checking the air pressure regularly is all that's needed. And I don't crank them on as tight as possible. I like the lithium grease idea.
Les
Les
MBWorld Fanatic!
Joined: Jan 2008
Posts: 6,621
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From: Naperville, IL/Chicago
2008 CLK63 Black Series 2012 C63 Black Series 2014 SLS Black Series
Are you talking about fusing or freezing? Threads on an aluminum valve stem cap will fuse to a steel valve stem but a steel valve stem cap should not fuse to a steel valve stem. I suppose it could rust or corrode. Like alloys will not usually fuse together. If you are talking about freezing I'm at a loss.
Senior Member
Joined: May 2007
Posts: 355
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From: Hong Kong/Charlotte
2010 C63
Interesting. I was sitting on the can looking through my new Performance Products catalog a few days ago and saw M-B and AMG valve stem caps being advertised as "ABS plastic!" which they apparently thought was a BFD, but confused me as ABS plastic ain't all that. Now I understand.
Thread Starter
Super Member
Joined: Oct 2007
Posts: 917
Likes: 1
From: Manassas, VA
10 Cayenne GTS, 07 Porsche 911 Turbo
The BMW caps are aluminum and they fused to the steel valve stems. BMW makes plastic caps for their TPMS equipped cars. I didn't know this and paid $85.00 for four steel replacement stems today. My tire dealer will break the old stems, deflate the tires, remove the old stems and then remount and balance all four tires. This has turned into a $200.00 mistake that I never thought could happen. I also purchased lithium grease and will use that from now on.
