Royal281

I'm having trouble with my C's driver front tire. It's loosing air and Discount Tire can't seem to find out where the leak is coming from. It has no nail and they said the valve stem is good. They filled it back up with air and put it in a tub filled with water and put weight on it to find a leak and nothing! So they broke the whole tire and rim down and "cleaned" it. It had been leaking slowly when I took it in yesterday, but the sensor came back on today to check the tire pressure. Anybody have any suggestions? Thanks...

vic viper

Fill a flower sprayer with water and a few drops of washing up liquid and spray on the tire, then you should easily see were the leak is.

Royal281

That's kind of what Discount tried... Said you would easily see the leak that way. But will try that out.

Carsy

Could be you have cracked your alloy wheel. I would remove wheel, pump it up to max allowable pressure & place it in a swimming pool or ect.. You should be able to see the trace of fine bubbles.

tanktube67

Is the tire is going flat? If not you may have a defective sensor.

bombardior

omg hey!! i have the EXACT same problem!!! took it in to midas, they could not find the leak. also driver front side tire.

and yes, it is actually losing pressure. it will drop from 35 psi to about 28 psi in like 2 weeks......

i have read somewhere that this may be a TPMS cracked/problem, which i heard can be very expensive to replace and not warranty covered.

JimPap

I had the same problem for better than a year until I tightened up the valve stem cores.

Note, you want to only tighten them slightly until you feel slight resistance. That will tell you that they're seated. Its better to use that special torque tool, but I found that it places the core too deep and its hard to put air (or as in my case nitrogen) into the tire. I found what works for me since I probably over tightened them is to use a special valve stem torque tool to back off the valve stem, add nitrogen/air, then tighten it with the tool till you sense the resistance....not so much that the tool clicks.

I bought my C300 from a Crown dealership who puts nitrogen in all their cars before delivery. My guess is that when they replace air for nitrogen, they didn't get the valve cores in there far enough.

Instead of having to add a couple of pounds every two weeks, its more like a pound every 6 to 8 weeks.

bombardior

hey jimpap
what is a valve stem core if i may ask?

JimPap

bombardio

This is an exploded view of the components that make up the tire valve stem. The part to the far right is a device used to tighten the core. I would not recommend this tool as its too easy to overtighten the core.

The core is the middle shiney piece with the red belt.

http://i.ehow.com/images/GlobalPhoto...F0386_Full.jpg

This is the proper tool for tightening but as I said in my earlier post, just turn the tool till you're sensing some resistance. Don't keep turning it till you hear the popping sound.

http://buy1.snapon.com/catalog/item....&group_ID=1668

bombardior

OH, is the black cap thing on the right what i would take off before adding air to my tire?

JimPap

Yes.....you're new to this, aren't you?

Petje

Had the same thing before my holliday, no leak on the tire.... by me it was the valve, rubber was leaking.

First the guy said, its not your valve. But i asked him to replace the valve and now its gone.

bombardior

yea.. im a car noob.... srsly

whiteongrey

I has similar prob lately - pin hole in sidewall after my wife drove over a curb. It was very difficult to find the leak.

Royal281

Thank you all for replying and sorry I haven't posted an update. I had taken it back to Discount and they replaced the valve stem as well as the TPMS sensor. They did it free of charge, but I believe to rebuild your TPMS kit there is like $10 a sensor. Tire seems to be holding air great now.

bombardior

how much would they have asked to fix at the mb dealership?

Royal281

Oooooh.... Don't know. Didn't even think about taking the car to the dealership for a tire leak. Although it took Discount 2 tries, they're a lot closer to me than a MB dealer. Tire still going strong, no leaks!!!