06 Cayman Valve Stem Issue

06 Cayman S owners without TPMS may have experienced a problem that I have had where the valve stem covers keep getting cut. Must be the centrifugal force of the high speed Cayman? Having already replaced two of these cheesy covers and with a third defective valve stem cover I decided to try another BMW solution. What do you think? These covers will not get cut. BMW part number 36-12-1-120-779 Retail price .95 US

u could get a chrome set of 4 from autozone for $1.99

mpollard - I have those on the 5-series wagon - they're great, but I've yet to have that trouble with the valve stem caps in 18k miles on the Cayman S. Good find! brad

Those are great, and the price is right. We use the inexpensive metal caps on all our cars for that very reason; the plastic ones break, and even split up the sides. And even though the metal ones may attract folks with sticky hands, the loss is manageable.

Mpollard, One of my valve stem caps did exactly the same thing and they put a new one on when I had it serviced. I bought the chrome caps with the Porsche logo in the tip, but someone told me not to use them because they might flex enough under force to scratch the rim! So I took them off. Russ

All 4 of mine split so I just took them off. I've been running without valve stems for a month now. I keep meaning to replace them but I keep forgetting. Any reason why I might need them on there?

To keep the valves clean. Avoid unintended deflation.

I haven't had any plastic caps split yet, even running autocross and track. It is fairly easy to over-tighten the caps and split them. Just tighten them down until you feel some resistance and stop there. For tracking, metal shafts (stems) and caps are recommended. The owner's manual warns us not to use metal caps (which surprised me), but they should work fine paired with metal shafts. Metal caps have rubber gaskets at the ends to prevent sudden loss of air through the valve stem. The use of caps is always recommended to prevent debris from entering the stem, possibly working against the valve core enough to cause a sudden loss of air.

Below: More photos of these caps. Still researching what the problem could be with the metal caps on rubber valve stems, especially when BMW has been using them for some time. Perhaps Porsche was cautioning aginst the use of logo valve caps which might weigh more and add to the unsprung weight? To be in compliance looks like I need to get the Porsche valve stem sleeve/cap 000-044-600-00-M100. Photo attachment below. Not to be confused with these.

The problem with the old valve stem caps is that you overtightened them. They'll look okay when you first put them on, but they'll crack later due to fatigue and temp changes. As mentioned earlier, the "cure" is to only put them on snug, not super tight. P.S. Around here, there are some knuckleheads that will actually steal the metal valve stem caps -- have had two sets stolen off the wagon. For that reason, I was actually a little relieved the CS came with plastic caps.

Stealing stem caps is getting popular among kids. Happens all the time. There are places that sell locking caps. Just google and you will find a bunch of them.

Adding weight to the end of the valve stem will increase the centrifugal force that the valve stem experiences at high rotational speeds. That force will bend the stem towards the rim. I would think that the stem can take it, but they (the people recommending against it) may be worried that in time the stem will crack or fail.

mpollard: in your last post... That last picture with the metal valve cap. Is that just a cap, or is that a stem replacement as well? (ie. can i have those put in my car now, or do I have to wait until my next set of tires?)

That is a one piece metal sleeve.

Valve stems Called a Crested Valve Cap by Suncoast ($14.95 for 4 including stems). Is this the sleeve/cap you stopped using, Russ?

Exactly the same thing happened to two of mine. I bought a package of 4 black plastic replacements for 95 cents at Discount Autoparts.

I just weighed the plastic cap that came with the car and the BMW metal valve stem cap on a kitchen scale, admittedly not a scientific instrument. Neither cap moved the scale measure.

I was thinking about the same solution, however I was worried about the added weight:crazy: If it happens to me, I'll deffienetly implement the BMW solution. Do I detect a pattern in your latest solutions ?

You detect my recent visit to the BMW Parts Department where I finally picked up some items that I have been thinking, for the last couple of months, might work on the Cayman. Sometimes it helps to expand beyond one manufacturer's parts bin

If you guys would just read the manual, you'd find the torque spec for valve caps...........wouldn't you??

I think Boothe makes a soft socket for tightening the caps.

valve stem caps The breaking of the plastic caps comes from tightening them too much, not centrifugal force. I've broken them on all kinds of cars and vans. Some of those "metal" ones are actually plated plastic by the way. Best solution, as stated above, is the cheap pack of caps from the local Autozone, Advance Auto, Pep Boys, etc.

Page 215 of the owner's manual: "Valves Rubber valve stems must be replaced every time a tire is replaced. For metal valves, the installation and replacement instructions must be observed. Use only genuine Porsche metal valves. Protect the valve inserts against soiling with valve caps. Soiled valve inserts can cause a gradual loss of air. Use only plastic valve caps. "

i wonder why porsche sells the color crested metel ones mpollard pictured, if the manual says use plastic only? i have the color crested ones and they have scuffed up my wheels a little bit. they are also terrible for track use because they get too hot to remove and adjust pressure. i've had several cars and have tightened the valve stem caps all the same and have never had this problem.

I still think the four caps delivered with my car are prone to easily being cut by the edge of the valve stem. Replacement plastic caps have not cut. When I finger tighten the original caps there never seemed to be a point at which I met resistance from the rubber part of the valve stem. The metal caps are shorter, so are smaller in size. This might explain why the weight is about the same as the plastic OEM caps? Below is a photo of an Audio R10 wheel at Laguna Seca. Looks like a TPMS valve stem...with a plastic cap!!

DO NOT use metal valve stem caps if you have TMPS The metal (I assume aluminium alloy) of the TPMS stems will be affected by bi-metalic corrosion when used with metal caps. This can cause the caps to "weld" to the stems. This is why the manual calls for plastic caps. It is also important that the tire shop you go to only use TPMS compatible valves when tire changes are done. Not an issue with non-TPMS stems as the brass threads of standard stems are not susceptable to the corrosion. I suppose application of anti-seize would work, but what a mess...