View Single Post
Old 12-22-2009, 10:17 AM
captainaudio's Avatar
captainaudio captainaudio is offline
Worlds Foremost Authority
Location: Upper East Side Manhattan - Lime Rock CT
Join Date: Jul 2007
Posts: 15,821
Mein Auto: M4 Cabrio - Cayenne GTS
Originally Posted by DSXMachina View Post
If your car has TPMS, and they all do since 2005, don't put aftermarket metal valve caps on the stems!
The stems require silver colored plastic caps, or nickel plated metal caps. If you use chrome plated caps, or metal caps made the old way then you may be in for a big surprise. I had to tow in a car today which the customer put metal replacement caps on two years ago. When he tried to remove the metal cap the valve stem snapped off, the core popped out and the tire deflated before his shocked eyes.
We tried every trick we know to get the other three caps off. We couldn't, they had become one with the valve stem. All four TPM sensors had to be replaced.
What is happening is that road salt is getting between the components and causing corrosion to accelerate. Eventually corrosion eats right thru the stem greatly weakening it.
Although I've read about this problem for a while in the trade mags, this is the first time I have personally encountered it.
So, a special advisory to you snow belt 'Festers; don't use those fancy looking aftermarket metal caps. You could get a rude shock one day when you go to add air to a low tire.
I think the main problem here is that he had obviously not checked the air in his tires in two years. As you are aware I use after market metal valve caps. I coat the threads with on the stems with vaseline before I put the caps on. I also remove them once a month to check tire pressures.

I rarely drive in road salt. I had to take the car out yesterday and when I got home it was dirtier than it has never been. It was washed as soon as I got back to the garage and is now happily sleeping under its cover.


Drivers Club at Lime Rock
The Glen Club (Watkins Glen International)
International Motor Racing Research Center
Cayman Club Nor'Easters
Porsche Club of America
Madison Ave. Sports Car Driving and Chowder Society (Only a Vice President)
Sports Car Club of America
Polish Racing Drivers of America (PRDA)
American Mural Project
Simeone Foundation Automotive Museum
Mount Washington Observatory
Society of Automotive Historians

Last edited by captainaudio; 12-22-2009 at 10:19 AM.
Reply With Quote