Valve Stem Failure -- Fact or fiction??

[Rollingon]

A friend of mine had an interesting experience last week. He had a rear tire go flat on his truck while driving on the Interstate, and took the remains to the local Firestone dealer. The store manager, who seemed very technically savvy, pointed to the valve stem and said "See those cracks in the rubber around the base? See the dust in those cracks? Your valve stem cracked, eventually started leaking, and the tire went flat." He said that age, stress from centrifugal force, and high pressure make it tough on truck valve stems.

My friend was not trying to get a warranty settlement on his destroyed tire, so the manager had no motivation to give him a song-&-dance story. They were new stems when he changed tires 3 years ago, so old age shouldn't be a factor. It sounds like a reasonable story particulary with the dust as evidence.

Does anyone have some solid knowledge on valve stem failure? Is there a particular type of high pressure stem that would prevent this? failure?

[chipper]

Does anyone have some solid knowledge on valve stem failure? Is there a particular type of high pressure stem that would prevent this? failure?
------------------------------------------------- :rolleyes:
Yep! Metal valve stems.

[mdadgar]

Yep! Metal valve stems. Those have been known to shear under stress (like in racing). Probably OK in this application (hell, I use 'em on my race car) but keep in mind that they are not a panacea and valve stems should always be replaced along with the tires.

- Mark

[DmaxMaverick]

Metal stems are great for street/show only. If you do any off-roading or drive in deep snow, they are a risk. Even snow packed against the wheel can cause them to shear off.

I've had a rubber stem start to leak and the cracks were obvious. I've found that the shorter stems are less prone than the longer stems. When I have tires installed, I request the shortest stems available, and have had no problems since. The rubber still checks, but I've not had one fail. I also use a slip-on decorative sleeve. The rubber doesn't check under the sleeve, and it remains flexible to prevent shearing.

[2jranch]

I was always told that any tires that run over 45 PSI should have the steel valve stems. Any time I have had tires replaced on 3/4 or larger truck I have sprung for the steel stems. Considering that you put 80PSI and then load the truck with a few thousand lbs., I would say cheap insurance.

[jbplock]

Interesting article on Valve Stems...

Customer Pays With Cheap Stems (http://www.babcox.com/editorial/tr/tr20134.htm)

I never thought much about this before... When ever I buy tires from Sams Club they always insist on using metal valve stems on truck tires...

smile.gif

[madmatt]

I've had both twist off in my hand while just removing the cap to check air pressure. I run flush stems in my Welds. You do have to carry an adaptor to air'em up but you don't have to worry about cuttin' a stem off while workin' your rig.

[Rollingon]

Thanks everyone for the replies. I'm learning more about valve stem than I ever thought I'd want to know. But since it's a safety issue with me (particulary when towing) I'm interested.

Jbplock's link stated that there are cheapie valve stems being imported that have inferior rubber not meeting USA standards, which age and crack quicker. Maybe my friend got those when had new tires mounted 3 years ago. How do you keep this from happening? At a tire shop we're pretty much going to get whatever they buy from their supplier. Where can we buy quality stems ourselves, then take them to the tire shop?

It appears there are several types of stems. One is the type that is secured on the wheel by a nut run down the threaded stem. This type is mostly steel, with thin rubber gaskets providing the air seal. These require a fairly large flat area around the stem hole on the wheel (which my factory alloys don't have) so they may limited to racing and specialty wheels. Another type is the familiar rubber "push into the hole" stem. There's more than one version of these - those with a metal sheath around the shank of the stem, and those without a sheath.

It's not clear what might be the best for us. Leaking is caused by cracks in the rubber where the stem fits into the hole, so a sheath may not do any good down there. It adds weight, which means more centrifugal force flexing the rubber in the hole.

Anyone have any great words of wisdom???

[jbplock]

Originally posted by Rollingon:
Anyone have any great words of wisdom??? Not great words :D but maybe you could ask your installer for the part number and brand of valve they use, then look up the specs to see if they meet the requirements refered to in the article (pressure & ozone).. You could also ask to see the package the valves come in to check for country of origin etc.. Seems like a reputable & knowledgeable dealer would welcome these kinds of questions.. ??

Quoted from http://www.babcox.com/editorial/tr/tr20134.htm

"Frank Banzanhof of Schrader Bridgeport International Inc., Muskegee, Okla., a manufacturer of OE valve stems, says many import stems are made of natural rubber rather than EPDM, a tougher synthetic rubber used in most quality valve stems. EPDM has a much broader temperature range than natural rubber, and remains flexible in the coldest weather. It also resists ozone and chemical attack that deteriorates natural rubber.

[Jim Brzozowski]

jbplock, good info about quality standards there, I thought I should mention one thing though. ISO-9000 can only be depended on to offer what the documents submitted for certification say you are going to do during manufacturing. I think its a good thing, its just that unless you know what the specs and standards are that a particular manufacturer uses, it doesn't help much. ISO-9000 only certifies that your are going to do what you said you are going to do. Of course if you are familiar with a companies standards its great reassurance.

[jbplock]

Good point about ISO 9000 Certs! Just because a company can pass an audit dosn't mean they always follow the process when the auditors aren't looking. :eek:

[trbankii]

Not just that they can do something else when nobody is looking, but that they can do exactly what they documented. They could document exactly how they are going to make a crappy part, make the crappy part, and achieve ISO cert because they made the crappy part they documented...

When I first came to that understanding, the whole ISO business lost a lot of value in my eyes. People see ISO cert and think it means that the item is quality. Just means they did what they said they were going to do and you really have to look at their documentation to see whether it is good or not... :rolleyes:

[carco]

We service a fleet of Ford E350-450's that use a valve stem of metal bonded to rubber. The problem we have is they leak between the rubber and metal or sometimes completely blow out. Tire work or replacement means new valve stem. One of our problems is that the drivers are to chk their own tire pressure regularly. Some drivers have a hard time bending and twisting the stem to chk and fill the tire, compromiseing the stem's integrity. Personally, I do not like this stem design and when possible replace with a metal stem. GM also uses this stem, why when one manufacturer uses something of lesser durability all other mfgs must use it also??? You would think one company would learn from another. bob.....

[hd90rider]

Put the short steel valve stems on mine over 200,000 miles agao. No probs.