3

Just replaced a bad inner tube with a new, Presta valve tube. Unfortunately, I seem to be unable to get any air in the tube; I hear air leaving the pump and not going anywhere.

I tried investigating the usual suspects:

  1. The pump is not sealed on tightly enough: Doubtful; several times I was able to lock the pump head so far down on the valve that it took considerable effort to remove it again.

  2. The nut on the valve was closed: Nope. Opened and closed the valve several times, pushed down on the valve enough to hear a minuscule hiss of air. The valve is open.

  3. Wrong pump type: Nope. Managed to inflate my other Presta valve tire just fine.

The only thing I can think of is that the complete lack of air pressure in the tube means there is nothing closing the valve, so the pump has nothing to depress and the sealing nut sits on the air opening. However, that sounds wrong to me.

Any ideas?

  • Is the old tube presta also? Using the same pump, can you get air into the old tube? If you can, this proves that there is no problem with the pump – PeteH Feb 3 '16 at 19:54
  • There are pumps with a 'dual' head for presta and other valves, and sometimes their mechanism to switch between the heads fails resulting in air coming out of the wrong head. But I guess you would have noticed that since you checked everything else so that's probably not it - thought it was worth mentioning for future visitors maybe. – stijn Feb 3 '16 at 20:52
  • 2
    Does it have a separate valve core? If so, did you try tightening the core? – mkpaa Feb 3 '16 at 21:30
  • It's unclear what you're describing. If you hear air going into the tire as you pump, and it does not come whooshing out when you pull the chuck off, then presumably the pump is OK. (Hardly any pumps depend on the Presta valve to prevent air from flowing back into the pump anymore.) Did you perhaps hole the tube while installing it?? – Daniel R Hicks Feb 3 '16 at 21:55
  • 2
    @stijn I have this issue routinely with new tubes. For some reason my stand pump doesn't push air through the presta side. When this happens, I inflate the tube just a bit with my mouth. After that it works normally. – jcbrou Feb 4 '16 at 18:27
4

Perhaps its obvious, but maybe the tube has a leak? Is it an old tube that has perished and is just letting air out as fast as you pump it in?

Perhaps try taking the tube off the wheel, put it in a bucket/tub of water, and then pump. Can you see bubbles somewhere?

| improve this answer | |
  • 2
    Excellent point - even brand new unused tubes can have punctures, which is why you test them before trusting them as your "spare" – Criggie Feb 4 '16 at 5:53
  • The inner tube was fresh out of the box, but I may need to try this. – A.H. Feb 4 '16 at 18:12
  • 2
    You should always slightly inflate a tube before inserting it into a tire. This helps assure that it doesn't get twisted or pinched during installation. – Daniel R Hicks Feb 5 '16 at 3:31
1

If you hear air leaving the pump and it is not going in the tire then you don't have a seal. If you have a seal and valve is blocked then you would not hear air leaving the pumpt

| improve this answer | |
  • Or what brenden said. – paparazzo Feb 4 '16 at 17:48
1

A presta valve on some brands have removable valve cores. If the pump is good, and the tube is not punctured, then there are 2 more options:

  1. The removable core is not seated properly, and needs to be tightened with a valve core tool.

  2. The valve core is bad/leaking, and should be replaced. If it is removable, replace the core only. If it is a one piece valve, replace the tube.

 presta valve with removable core and descriptions

| improve this answer | |
  • 1
    The valve core doesn't appear to be removable (I may be wrong), but I didn't know this about Presta valves. Thanks. – A.H. Feb 4 '16 at 18:22
  • Not all of them appear as obvious as the one in the photo. Check the threaded section below the valve tip. If there are 2 flat sections on this threaded area (you can just see them by the top red arrow above) then it unscrews. If the threads go all the way around with no flats, then it does not. – zenbike Feb 6 '16 at 0:13

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.