Community Forums

pilotspike · 08-13-2016, 04:43 PM

I have installed a TST 507 system on the coach and for the most part it has been perfect. I have one wheel however that refuses to either report, or if it reports its very low or doesn't show an expected pressure increase while driving. This is specific to the wheel as I can swap sensors around and have the same problem.

I spoke with TST and they believe that the valve core is likely a tick too far down in the stem and that I should be able to unscrew it a tad to fix my problems. This makes sense to me as when I remove that sensor I dont get the air 'whoosh' that I would expect. Though I can use a normal tire pressure tool and get valid readings.

My question is this; How do I do this? I haven't messed with valve cores. I know I can put a valve stem tool down in there and unscrew the core to get it out of the stem, but is it possible to screw it out a tad without causing an air leak? I would have expected that it is seated on some type of face in the stem that prevents it from leaking.

John

powderman · 08-13-2016, 05:20 PM

Unscrewing the valve should work, however if by chance the sensor came loose you could leak down. I think a better approach would be to change out the core with a new one.

wam16 · 08-13-2016, 05:44 PM

I had a similar problem on one of my tires. Unscrewed the core 1/4 to 1/2 turn and it works fine. Hope yours works as well.

Allen

lass · 08-14-2016, 07:22 AM

Pilotspike, I had this same situation on my inner dully's and traced the problem to the Haltech 4" extenders. Went thru the valve core adjustment process, no change in reading. Bought new cores and original Haltech extender and still no change. So if you don't find an immediate solution, I recommend buying a set of Wheel Master extensions from CW or TST for $15.00 and fix the problem once and for all.

Had I know this in advance, I wouldn't have wasted months playing around. Its been over a year since the change and is still working as advertised.

wil01 · 08-14-2016, 10:50 AM

I had that problem on one inside rear with the valve extender I had installed when I bought the coach

I replaced that valve stem extender with one from a local source. It worked just fine for about 800 miles. Then I got your exact symptoms.

TST advised they had not had any problems with the extenders they sell. I ordered two of them and installed one on the wheel with the problem. Problem solved!

All valve stem extenders are not created equal. Get the ones from TST and I think your problems will go away.

Replacing the OEM valve stem on an inner rear wheel isn't really easy and much of the success of doing that depends on the skill and interest of your tire shop. Remember that the valve stem should be centered in one outside wheel opening. My tire shop had little interest in doing that.

Remember that the entire valve stem should be solid metal, not any flexible metal or rubber of any kind.

And finally, the tire tech had to make adjustments on that locally supplied extender before it would work even for a short time. No adjustments of any kind have been required on the TST extender.

Good Luck!
Wil

pilotspike · 08-21-2016, 10:33 AM

Didnt fix my problem. I backed out the cores of the extender and couldn't solve the problem. I even managed to back it out enough that it came out in my hand and I had to put it back in.

I talked to TST and they suggested replacing the extenders with the ones that they sold, just as Wil suggested. I know nothing about pulling the simulators off and replacing the stem extenders. Will I need a tire shop for that or is this something a handy man can do?

Maintenance on my other vehicles doesn't intimidate me, but messing with tires that are carrying 20K lbs makes me think twice.

John

Tireman9 · 08-21-2016, 10:53 AM

There are two types of extender hoses. Pressurized and "air less"
The pressurized have an "open" end that screws onto your metal stem on the wheel You should hear a little air leak out as the hose is screwed on. You should tighten the host "finger tight" which is about 1/2 turn to 1 turn after the air stops leaking out at the wheel end. The outer end of the pressurized hoses have a standard valve core. The little pin of the valve core should be just about flush with the end of the hose threads. If the vore has been over tightened and the core pin is too low it will not open when you use a pressure gauge or air chuck or TPMS. All of these items have a pin that is designed to press against the core pin and open the air chamber in the hose.

Airless hoses have a special type of valve core at the outer end. The intent of this pin is to open the tire valve stem core and to allow air into the interior of the hose. The outer end of this special core is like a regular core but if the long extension is bent it may not work properly. When you install this type of hose extender you would not get an air leak when installing it as the long pin would not activate the valve stem core.

find a valve core that is too deep into a valve stem or into a hose extender it should be replaced as it may have been over-tightened and its sealing surface may have been damaged. Simply get a new core and replace it. Do not over tighten. Valve cores should be finger tight (1/4 to 1/2 turn) after air leak stops. Any tire dealer should be able to change valve cores in either a standard valve (rubber or bolt in) or in a "pressurized" hose extender. The special valve core in some "air less" extender hoses may mean the entire hose needs to be replaced. You can contact the vendor of airless extender hoses for more information.
If you ever

wil01 · 08-21-2016, 06:41 PM

Let me add a note about the TST 507 sensor installation that isn't contained in the instructions, but is recommended by TST.

Slowly hand screw the sensor on to the valve stem. Listen carefully as you screw the sensor on to the valve stem. As you proceed, you should listen carefully and should hear air escaping from the tire as you proceed. At that point you should continue to screw the sensor until the escaping air stops. When that happens, the sensor is properly attached to the valve stem and should be just hand tightened after that to secure the sensor.

If you don't hear the air escaping, there is most likely a problem with the valve stem or valve stem extender. If it is a valve stem extension problem, I suggest getting one from TST. I had that problem and the TST valve stem extension solved the problem completely.

If you have the pass through sensors, I suggest that you take a pressure reading on the tire before you install the sensor with a good tire gauge. Then after the installation take another pressure reading. The two readings should be the same. A lower pressure on the second reading indicates a problem with the valve stem or extender.

After you obtain the proper installation, future problems are unlikely to occur.

Good Luck!
Wil

Archer2 · 08-21-2016, 07:17 PM

It is wise to make sure that no part of your body or hand is directly in front of the valve stem as you unscrew the valve core. 110 psi behind a 1/4 inch piece of metal would be a lot like a .22 short round being fired. Better safe than sorry.