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TPMS Valve Stem Caps - Warning!

45K views 79 replies 29 participants last post by  Augster 
#1 ·
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.
 
#2 · (Edited)
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.

CA
 
#7 ·
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.

CA
Absolutely right and that's what happens when we come to think that electronic devices are going to save our *sses. Why should he check his pressures, the TPMS will tell him when the system needs attention! Yeah, right.:mad:
 
#4 ·
Galvanic Reaction. Years ago I was installing the sprinkler system in a Post Office. When it came time for the punch list corrections, one item on the list was a 1/2" brass nipple in the otherwise galvanized piping for the alarm valve. Shaking my head in disbelief, I approached the inspector (Lieutenant, Army Corp of Engineers, newbie) and asked about it. He says that the brass nipple has to be removed due to possible galvanic reaction. I started laughing and pointed out that EVERY valve (drain valve, inspectors test, check valve..) in the system is brass and oh yeah, what about ALL the sprinkler heads, they are brass, what are we gonna do with them? He agreed and the nipple remained. Bottom line, No Electrolytes (salts), No Corrosion, at least in sprinkler systems. :thumbup:

dj
 
#27 · (Edited)
Galvanic Reaction. Years ago I was installing the sprinkler system in a Post Office. When it came time for the punch list corrections, one item on the list was a 1/2" brass nipple in the otherwise galvanized piping for the alarm valve. Shaking my head in disbelief, I approached the inspector (Lieutenant, Army Corp of Engineers, newbie) and asked about it. He says that the brass nipple has to be removed due to possible galvanic reaction. I started laughing and pointed out that EVERY valve (drain valve, inspectors test, check valve..) in the system is brass and oh yeah, what about ALL the sprinkler heads, they are brass, what are we gonna do with them? He agreed and the nipple remained. Bottom line, No Electrolytes (salts), No Corrosion, at least in sprinkler systems.
There's more to it....the higher the proportion of copper or copper alloy to iron, the faster iron will corrode in water, or it's sacrificial anode, zinc [galvanizing]. And vice versa. Copper will be inhibited.

Galvanic corrosion will proceed without salts predissolved in water. Pure water is relatively agressive stuff. Certain salts in high concentration are used to prevent corrosion.

If you have chlorides (road salt), they'll do a number on some metals without galvanic corrosion, in the wet.

Road salt and galvanic corrosion (current flow) will certainly cause corrosion when wet.

All above requires water to complete the corrosion cell. Vasoline prevents water/metal contact, so no, or greatly reduced, corrosion.
 
#8 ·
Captain/DSX,
Please clarify re: "aftermarket valve caps". Are these one and the same as the caps sold under the P/N 36 11 0 009 840 that are available from BMWUSA?
 

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#9 ·
If they are not plastic, and you are worried, do what CA did and Vaseline them. No Worries. :)
Also presumable you check your tire pressure more often than every 2 years. :rofl:

dj
 
#10 ·
Our Acura MDX (and my dad's Honda Rdigeline)--both with TPMS--had a safety recall for this exact issue. The vehicles came with metal caps standard, and Honda just mailed out four replacement gray plastic caps to every registered owner on file, with the instructions to swap them out.
 
#11 ·
It does not take 2 years for galvanic corrosion to wipe out your valve stems. My MDX valve stems froze to the metal caps in one summer stored in my garage basement. The tire pressure checks you all seem so fond of making your selves are not necessary in the MDX because the TPMS reads out in PSI so you can check your pressure any time (and watch them change as the sun hits the tires on a freeway good for 1-2 PSI depending upon the season). So when I put my tires on in the fall, all 4 stems were frozen, and I don't carry Vaseline or any anti-seize for my schrader valve stem caps so don't even start with that.

Cost the boys at TireRack 4 TPMS, mount and dismount, plus my friendly face in their office for an hour!

BTW, who checks air pressure every month? Do you all have leaky valve stems? Tires hold air, then they go flat, why check them all the time? My BMW tires hold air, all the time, every day, it's weird, but I think tires are supposed to hold air.
 
#12 ·
It does not take 2 years for galvanic corrosion to wipe out your valve stems. My MDX valve stems froze to the metal caps in one summer stored in my garage basement. The tire pressure checks you all seem so fond of making your selves are not necessary in the MDX because the TPMS reads out in PSI so you can check your pressure any time (and watch them change as the sun hits the tires on a freeway good for 1-2 PSI depending upon the season). So when I put my tires on in the fall, all 4 stems were frozen, and I don't carry Vaseline or any anti-seize for my schrader valve stem caps so don't even start with that.

Cost the boys at TireRack 4 TPMS, mount and dismount, plus my friendly face in their office for an hour!

BTW, who checks air pressure every month? Do you all have leaky valve stems? Tires hold air, then they go flat, why check them all the time? My BMW tires hold air, all the time, every day, it's weird, but I think tires are supposed to hold air.
So tires have two states, full and flat?:dunno:
 
#23 ·
'Last time I stopped by the dealer, they were still selling both sets of caps: metal and plastic. They look the same, but the plastic ones, of course, feel much lighter and won't cause a problem.

To get the corrosion you need metals that are rather far apart on the galvanic series (http://en.wikipedia.org/wiki/Galvanic_series) and water. Pure water is a lousy electrolyte. Dissolve a salt in it, and you're good to go. But there are plenty of other impurities that can make water a better conductor and accelerate corrosion. So... even if you're in an area that never salts the roads (lucky you), I'd still be wary about the whole valve cover thing.

And, btw, I had a flat recently. The RFT didn't look flat at all (naturally). Really. How hard is it to check tire pressures?
 
#24 · (Edited)
Now that I am aware of this issue I immediately went down to the garage and removed the fancy metal BMW logo caps and replaced them with the original cheap plastic ones.

The results were instantaneous and spectacular. My migrane headache went away, my acne cleared up, the interest rate on my IRA doubled and I won $500 in the New York State Lottery. This was particularly amazing since I hadn't even purchased a ticket.

CA
 
#26 ·
Now that I am aware of this issue I immediately went down to the garage and removed the fancy metal BMW logo caps and replaced them with the original cheap plastic ones.

The results were instantaneous and spectacular. My migrane headache went away, my acne cleared up, the interest rate on my IRA doubled and I won $500 in the New York State Lottery. This was particularly amazing since I hadn't even purchased a ticket.

CA
Now you've done it, Captain!
I'm going to have to take a walk on the wild side, invest in a set of fancy BMW logo caps -- just so I can take them back off and see what fate throws my way.
 
#31 ·
This could be a huge quality/satisfaction issue for BMW and people who have fallen victim to this should file a class action. I had the same problem after buying the little logo caps at the BMW dealer at the parts counter. Fortunately a mechanic was able to remove the caps with a pliers for me - but if I had to put air in a tire myself for some reason before that day - forget it, i would never have been able to get the caps off. BMW dealers sell these caps that essentially fuse to the valve stem in their own dealer parts departments. Anything to make a buck I guess....
 
#33 ·
This could be a huge quality/satisfaction issue for BMW and people who have fallen victim to this should file a class action. I had the same problem after buying the little logo caps at the BMW dealer at the parts counter. Fortunately a mechanic was able to remove the caps with a pliers for me - but if I had to put air in a tire myself for some reason before that day - forget it, i would never have been able to get the caps off. BMW dealers sell these caps that essentially fuse to the valve stem in their own dealer parts departments. Anything to make a buck I guess....
Going to court over this? BMW owes some people some new valve caps and needs to replace a few TPMS sensors. They will probably take care of it.

On the other hand sh*t happens.
 
#32 ·
The source of the problem is that the valve stems which used to be brass or steel are now aluminum. Ferrous and red metal can't be used because they act in opposition to the antenna located in the TPMS sensor. For whatever reason, and my RF energy knowledge = { 0, the aluminum doesn't interfere with the signal.
Steel valve caps+aluminum valve stem+CaCl+H20=doodoo. That's the limit of my chemistry, too.
 
#41 ·
The set that I have is definitely made of metal and the TPMS system appears to work fine.

CA
 
#46 ·
Did you ever notice those little floral doohickies they put in the front of the real ones between the ...um...headlights? My friend got a car bra and made an appropriately sized floral thing and fastened it to the middle. If you 'got it' it was hilariousl. Not many people got it though and he took it off.:(
 
#47 ·
So I got the OEM BMW logo caps for Xmas. They are indeed metal, and there's a sticker applied to the back of the package which reads: "Warning: Brass material valve stem caps are to be used on brass stems only! They are not recommended for use with aluminum or aluminum alloy material tire stems. In this application, please use our ABS Plastic material valve stem caps."

So are our stems brass or aluminum? :dunno:These aren't aftermarket-they're Bmw parts.
 
#51 ·
An alternative to Vaseline would be electrical contact cleaner which is readily available in spray cans at Radio Shack. Spraying this inside the caps before they are attached should prevent them from fusing.

CA
 
#52 ·
Got an idea that might work. What about the nylon tape you put on threaded pipes for plumbing jobs?
 
#58 ·
Of course the low tech solution would be to simply unscrew the caps and screw them back on periodically.

Or of course you could also hire someone to do it for you.:rofl:

CA
 
#59 ·
Get the dealer to do it. He'll probably charge you $50 per tire, while assuring you that only BMW dealers know the right computer codes to do it, and I'll reminding you that the tire stems are not covered by BMW's 4-year maintenance program.
 
#60 ·
I am a new BMW owner and just got my 09 335i in May of 2009. The first day the temp really dropped here I start up the car and it said I have low tire pressure. I took it to the local tire shop and he, also a BMW owner, said that a drastic weather change can cause this??? Anyway....as he was removing the caps to check the pressure...one of the caps broke! I am due for my first service next week so I am going to see what exactly broke.

This car is really different than anything I have ever owned and its a learning curve for me....lol.
 
#61 ·
FWIW: Valve Stem Cap Update

Just got back from running across the freeway to the dealership to acquire the roundel valve stem caps. I took the P/N off the BMWUSA website (36 11 0 009 840). The parts guy queried me as to year and model before he retrieved the caps. He told me I had the wrong P/N which is for the metal caps which in his words, "will mess up your TPMS".
He said he had the right caps in stock and came back with P/N 36 11 0 421 544 which are most definitely plastic caps that have little o-rings in them. The verbiage on the back of the package states the caps "feature an 'O-ring Seal', insuring consistent tire pressure and a clean valve orifice when removed."

Yippee! TPMS Safe and Stylish!!
 
#62 ·
Interesting. I have a set of those Roundel stem caps that I never ended up putting on my '06, but did put on my '09. I take them off all the time when checking pressures. I can not imagine going months, much less years, without checking it. I even check my lug nut torque!
 
#63 ·
Hundreds of dollars of TPMS equipment is totally wasted on you and others like you who can be depended on to properly maintain their vehicles. All these gadgets and gizmos like TPMS and 'electronic dipsticks' and coming soon, the 30K oil changer interval, are designed to protect people from themselves.
I have hundreds of customers who NEVER check their tire pressures. Ever. One of them was the guy who snapped off the valve stem when he tried to remove a seized on cap. Oops.
 
#64 ·
I just noticed on my wife's MB that the front caps are metal but very short whereas the rears (we just replaced the tires) are plastic. The fronts are also relatively new. I used 2 different places to mount and balance the front/rears and I wonder if one got it right and the other.... She does not report any TPMS problems and since we are giving it back soon and I do unscrew them to check the pressure I'll let it ride.

My 911 came with plastic caps, but I am missing one:eek:
 
#65 ·
I have the BMW Fancy caps I purchased from Tisher.

I have had them for two winter now without problems.

the bigger problem in the northeast states is that they have started to use liquid salt products. Many may say "all salt melts yadda yadda" -- yes, but this liquid stuff is horrible and if it splashes on your car before it has had chance to be diluted with snow, it does leave a mark and have already seen how it can crust on and leave dull finish where is stayed on the car too long. Has not happened to my bimmer but I have seen it on a few at my work parking lot.

I spray off my car with a hand sprayer before putting in the garage. The nasty liquid stuff is going to cause a whole host of new problems because its going to get into places not fully protected!
 
#66 ·
Just checked my tire pressures when I put on my new valve stem caps... Uniformly 1lb loss since the last check (early November), which I attribute mostly to temperature differential. I know, I should do this on a monthly basis -- but time flies by sometimes. :nono:
 
#69 ·
Just checked my tire pressures when I put on my new valve stem caps... Uniformly 1lb loss since the last check (early November), which I attribute mostly to temperature differential. I know, I should do this on a monthly basis -- but time flies by sometimes. :nono:
Ummm, yeah ... at least :p
 
#67 ·
Now that DSX has enlightened me about metal valve caps I have had to change my plans.

Obviously plastic is completely unacceptable to a person of my impeccable taste. Of course I certainly did not want the metal caps to fuse to the valve stems. I pondered this dilema and then the solution came to me. GOLD! I contacted Tiffany's (I go there every morning for breakfast) and arranged to have them make me a set of 24 Carat Gold BMW Logo valve stem caps.

If anyone else is interested send $800 in cash to:

CaptainAudio Enterprises
PentHouse
Trump Tower
5th Ave.
New York, NY 10021

CA
 
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