Does anyone in this forum have any inking as to the root cause of leaky TPMS valve stems? They are driving me nuts. I probably have experienced 8 stem leaks in three years, half them old OEM stems and the other half previously repaired with new Schrader p/n 20032 stem rebuild kits. I have two Gen II Prii, both with odometers at 185k+ miles, both purchased new. In the first 100k miles neither car had leaky valve stems. I keep in my garage a nifty Harbor Freight tool that breaks the bead on tires, so I can address these leaky stem failures myself. Tire shops refuse to deal with the problem. They love to sell $130 tires, but not fix leaky stems. The stems generally leak through the threads at the top of the lock nut, occasionally at the interface between the lock nut and the rim. These leaks aren't "whistlers". I lose about 5 psi per week. The TPMS sensor itself plays no role in this dilemma. On Prius sensors the TPMS electronic module is a separate subassembly bolted to the bottom of the metallic valve stem. It does not participating in the pneumatic seal. I could omit the electronic module entirely and the stems would still leak. So the vendor for the TPMS sensors is not relevant. However, it is true that I have been buying Dorman replacement sensors when the batteries in the factory sensors die. While I have my hand inside the tire, I wipe down the rim in the area of the valve stem. I never detect corrosion here. I always replace the OEM rubber grommet with a new one from the Schrader rebuild kits. I torque the lock nut down to the 35 inch-pounds printed on the Schrader rebuild kit. Recently I have started lube'ing the threads and grommets with some quasi-liquid stuff called Nylog Blue that HVAC guys use on their hose joints to get tight evacuations when they pump down refrigeration gear. Nylog is a clear, thick syrupy goop that never dries. It seems to help a little, but I've even observed some of the Nylog'ed stems leaking within a couple of months. Any thoughts you might share with me on this are appreciated. FWIW, I have observed that the rubber grommet begins to extrude/flow and deviate from its normal profile when you exceed the torque spec even a little bit. I've wondered if the slippery Nylog is lowering the torque threshold at which the grommet begins to extrude. My gut instinct is that there isn't enough "meat" in the rubber grommet given its importance, but they seemed to work fine for the first 100k miles of the cars' lives. Jim Olson Indianapolis, IN
Not on Prius, but on my old HCH, I have had numerous TPMS troubles including leak around the stem. That was all on OEM Pacific TPMS 7-10 years old. The car was the first with internal TPMS sensors I have ever owned. Not knowing the law well, I have taken the car to a dealer to have them fixed for $$$$. If I had known what I know now about TPMS, I would have simply replaced all TPMS sensors with regular valves and just lived with the TPMS light on the dash. That would have costed me $15/tire at top, instead of ~$200/tire I had to pay to a dealer. How old are your leaking stems? Are they all metal stems? My experience has been TPMS older than 7 years old with metal stems are prone to leak. This can not be fixed with just TPMS service kit which replaces only core, grommet and a nut. And OEM TPMS can not replace just the valve stem without replacing entire sensor. Replaceable rubber stems (or metal stems if you prefer) found in Autel TPMS sensors seems to be the way to go.
My VW Routan (Chrysler minivan variant) has serious OEM valve stem failures on the highway, This is known defect due to salt corrosion over the years on the aluminum collar they used, I believe there is a class action suit against Chyser as this impacted many models. Have not seen or heard any Prius issues like that. I've replaced those bad ones now. I've gone with Denso both vehciles. I bought one Schrader programmableTPMS which was a mistake because the tire place did not know how to program it, and I did not have the neeeded programmer tool.
Well, first time I've read about or even known this to be a problem. My first suspicion is that something is wrong with your Harbor Freight tool or the DIY process you're doing. Second thought is as post #3 suggests try a different brand of TPMS...
I own a generation three Toyota Prius, and Val found one of those valves stems leaking. I read everything on this post and realized, with my Plumbing experience. It’s just a leak that needs to be repaired. I haven’t done it yet, because it’s still wet from spraying Windex on it to get it to make bubbles so I know where it was leaking. After it dries out, I’m gonna go down and get some adhesive caulk or clear silicone and fill the void between the rim and stem. Should be the end of the problem.
Nope. External sealants won't work. There is leakage because the aluminum is corroding. Specifically there is corrosion between the rubber seal of the valve stem and the metal of the hole in the wheel. The only way to repair such a leak is to dismount the tire bead and remove the TPMS sensor assembly. Clean the corroded areas of the wheel and paint with good clearcoat. Install new seal kit for the valve stem (I also use some bead sealant). Usually I also have corrosion on the bead seat area on the wheel. Clean and coat that as well. Refit the tire & rebalance. Posted via the PriusChat mobile app.
I replaced all 4 TPMS sensors on my Prius years ago- I replace them all with good old regular tire valve stems
Totally agree, that’s been our setup with snow tires on our 2010, for about 5 months out of the year. When the stock sensors (on the all-season tire set) finally fail, I’ll just do nothing, and replace with regular valves if-and-when the tires are replaced.
I hated the idea when they came out and still do. When new tires go on a car that has them I always specify good old rubber stems. Having some standard monthly maintenance on a car is not bad. Check fluids, tire pressure, clean windows inside and vacuum the carpets.
