What is this tube in my trunk?

[bigburrrd]

Hey everyone,

I have an '89 325i and I was putting taking the negative wire off my battery to do some work and I noticed there was a bunch of standing water in the battery tray and below. I wet vacced it out and also found this tube with a plastic fitting on the end. I got the car about a month ago and am just doing general maintenance, it's in great condition and I'm baffled as to what this could be. Does anyone know what it is and possibly if its related to the leak?

http://imgur.com/UqqP68e

(I don't know how to embed photos in the post so bear with me)

Thanks!

[Todd Black 88]

It's the vent that attaches to the battery itself, if your battery has a vent. The clear piece on the end is from a battery, mine doesn't have that.

[e30_world]

☝��☝��☝��batt vent. I have the same batt, should plug into the top middle right side

[bigburrrd]

Thanks for the quick responses! I never would have guessed it was a battery vent.

[Das Delfin]

You want to use the battery vent because it collects sulfuric acid in the form of a vapor. Usually people don't know to hook this back up and this is why the battery tray is always rusted out

[Cephas]

Yes, it also vents hydrogen which is a byproduct of charging a flooded cell battery. Hydrogen happens to be incredibly explosive (Hindenburg).

The tube in your pic wont fit your battery. Luckily for you, interstate has a vent kit that they give away that will connect the oval shaped one on your battery to the round one already in your trunk.

This vent must be installed. You risk rust or worse without it.