Last post on Feb 12, 2011 at 7:22 PM
You are in the Subaru Legacy & Outback
What is this discussion about?
Subaru Legacy, Subaru Outback, Sedan, Wagon
#18 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [pilot1226]
Mar 05, 2010 (5:42 am)
Not that I have ever heard. It is simply a monitor system, and not reactive.
I still think there is a leak somewhere. The problem with a tire bath is that it is a 'no-load' test. Your tire might only leak out a small amount of air during certain dynamic operations, such as hitting a bump or pothole, cornering loads that push against the bead, when hot and the internal pressure exceeds a certain threshold, etc.
It could be a rim problem, where the tire meets the rim, or the TPMS/valve unit itself.
#19 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [fibber2]
Mar 06, 2010 (9:27 am)
Okay, that makes sense. So, if I bring it to the shop where I had the one tire replaced (a Yokohama retailer nearby), what kind of test(s) should I be asking for, and what's a reasonable price for it?
#20 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [pilot1226]
Mar 06, 2010 (10:15 am)
I had a slow leak (1 lb/wk) on my 07 and took it to a tire place. They used a water bath and had trouble finding a leak, but finally found a leak around the tiny gasket used to attach the TPMS unit to the rim. They showed me where it was corroded, but not from rust.
They told me that the material the gasket was made of was reactive to the alloy wheels which caused corrosion and then a leak. They replaced the gasket with one of a different material. They said there was a Bulletin out on the problem.
I don't remember whether the new gasket was silicone or whether silicone was the one that was reactive to the wheels.
I later mentioned this to my Subaru dealer, and they were not aware of the problem.
We've also had slow leaks around the rim due to corrosion from the salt used on the roads here. I don't think your car is old enough for your leak to be due to this problem.
#21 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [snowbelter]
Jan 17, 2011 (1:57 pm)
Another winter is here and sure enough this same issue persists. Only in the colder months - when the temperature outside is around or below freezing (32F), the TPMS light will come on affecting the front two tires. This is persistant, despite rotations. I think there may be some type of problem with the Yokohama tire itself?
When I fill it to 33PSI cold, as the door jamb suggests, it lasts for about 2 days, then the light returns. It seems the front tires will "stable off" around 27PSI and won't lose any more air at this point.
The rear tires have been a solid 30PSI and don't require any air.
But, considering all the quarters I've put into air pumps at the local gas stations, I might as well have bought new tires by now.
Do I have to have the lower-profile tires with the Legacy, or is there a way to get a conventional tire profile for when I get these things replaced?
#22 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [pilot1226]
Jan 17, 2011 (7:24 pm)
That does seem odd. When the temperatures drop however, your air pressures will go down, causing the TPMS light to come on. I would pump em up to 35psi and see if they can stay stable.
Subaru Guru and Track Instructor
Jan 17, 2011 (8:13 pm)
According to TireRack.com, the Yokohamas on the Legacy are Yokohama Advan A82A (Ultra-High-Performance All Seasons) 205/50R17, V rated though I wouldn't be foolish enough to try to push 149mph in Northern Jersey, too much traffic!
Max inflation pressure is 44 psi, so I'm comfortable to inflating it to 35psi in that I won't pop them in highway driving as the pressure increases.
Since the light is on - again - I'll go and hit the nearby pump one last time and we'll see how long it lasts. Driving doesn't seem to affect it in anyway, so the only thing I can think of is some bad contact between the stem and the tube or something along those lines, but it's so weird because it only affects them when they're in the FRONT, meaning the pressure from the engine is really pushing on them.
At any rate, what are your opinions on Michelin Pilot Sport A/S Plus or Pilot Exalto A/S? The Sport Plus is a little bit more money ($10 per tire, give or take), but the treadwear is 500 as opposed to the 400 of the Sport Plus. The Sport Plus is also listed as High Performance, whereas the A/S is "ultra-high."
Thanks, will check back in a few days. If it weren't for this tire glitch, I would say the Legacy is a perfect car for my needs. (Though come spring we will be selling our Nissan and getting a new Outback!)
#24 of 34 Re: Will do. [pilot1226]
Jan 17, 2011 (8:19 pm)
Hey, I'm in NNJ too! If you wanted to come by our shop we could check it out for you and see what's up.
I love the Pilot Sport AS Plus. I got them free with a set of rims recently and drove em for about 6 months. They are actually very amazing.
Subaru Guru and Track Instructor
#25 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [pilot1226]
Jan 17, 2011 (9:12 pm)
This is a long shot, but lets see if it holds water (pun intended...).
You mentioned $1 air pumps. Ever not make a good seal to your schrader valve and see all of the water spray out? Common, as these standalone outdoor compressors are usually poorly maintained.
Ideally, you want a dry tire fill - nitrogen/oxygen. Then the pressure follows the basic relationship of the Ideal Gas Law (linear change in pressure with change in temp). Water changes that, as the relative humidity within the tire rises with decreasing temp, condensation forms, then it freezes. This phase change makes the whole pressure relationship non-linear. Worse, if the water works its way into the bead and freezes, it could unseat the tire and cause a leak.
Granted they use various composition bead sealers and lube when they mount the tire, but you might have a lot more water in there now than you should. I also wonder if this isn't also part of the corrosion problems at the TPMS seal others are reporting.
When you change tires, have them inspect the bead seal area, and wipe everything down before mounting the new tires.
For $35 you can buy yourself a very nice little compressor and stop filling your tires with crud.
Jan 18, 2011 (1:58 pm)
after reading a bit more, I decided to buy the Black and Decker cordless inflator. Seems like a sturdier unit, can be "charged" and also can run off the vehicle's 12V port... There were a few reviews that the cord on the one I previously listed was too short to reach the rear tires (lol!)