Why does my inner tube have brown liquid inside? Now with internal photo I flatted the front wheel going up a climb the other day - I heard the pop and the PSSSSHH, and I could see a geyser of pale "steam" or vapour coming out the puncture.

I swapped out the tube for the spare and continued, but noticed the tube was wet inside the tyre.  It hasn't rained on my bike for months.

When I got home I patched the tube, and noticed a lot of dampness around the hole.  When inflated it bubbled like a mud pool.  The tube also felt squishy and I couldn't push all the air out when stowing it later.

I guessed there was some water inside, so the tube was left hung up with the presta valve at the bottom and unwound.

8 hours later this is what it looked like underneath:


Bigger photo of the pool - this is 10 hours of draining time:  Quantity is about 5-6 dessert-spoons full (estimated)


The liquid was runny not viscous, and was clearer on top with the colour sunk to the bottom.   The coloured bit looks like mud, or a suspended powder

The tube is labelled as "CST 700c 19-23" and a long number  There is no mention of any sealant or puncture resistance to this tube.

Why does my tube have brown liquid in it?

EDIT:  I removed the valve core and tried to purge the goop using a rolling motion.  It didn't work so I junked the tube.  I cut it open to see what was blocking the open valve, and it looked like this:

Not the best photo sorry, but its a jelly-like mass with many black dots like grains of sand.  I suspect these are suspended fragments of butyl rubber from the inside of the tube.


TL;DR?  Squishy tubes are bad - buy a new one.
I've seen that color before. If you are filling from a compressed air tank, make sure the tank has been bled recently. More frequently in humid areas air tanks will get condensation inside. Normal maintenance is to bled the water out of the tank. The condensation rusts the inside of the tank and can eventually cause tank failure. When you put an air line on them the air comes out but a little vaporized water goes too. That gets in your tubes and builds up over time if you use the same filling source. Avoid by placing an in-line filter on your air hoses as well. Test by blowing air over your hand from a safe distance. If it's wet or damp you have found the culprit.

Experience case: They didn't bleed the compressor at the beach shop I worked at. I bled it when we upgraded to prep it for storage. One gallon of water came out of that little six gallon tank. One-sixth of the volume for air was taken up by the water and it was the cloudy brown milky color too.

Also, respectfully agreed. White liquid is often stop flat liquid filled into a tube as a flat preventative. Stop flat can be neon green in color too.