What's the purpose of this hose?

 

As the rear end gears mesh over a period of time they build up heat which causes the air to expand inside the rear end so they provide a vent to allow the pressure to equalize with the outside air pressure. One end of this hose connects to the vent port on the rear end and the other end is pushed up into a sheet metal cavity directly above it.

 

If you remove the hose and plug the port it will probably blow the seals out of the rearend in other words, it's got to breathe.
jon

 

Thanks, I was looking at replacing the hose because it's seems to be the original and looks pretty bad so just was curious as to what it did.

 

Mine was plugged with dirt when I started driving my car after sitting for 18 years. Blew the rear axle seals leaking nasty gear oil all over my newly rebuilt brakes. I fixed that with a new fitting and a new vent hose and new axle seals (after rebuilding the brakes again). It does serve a purpose
I fixed that issue with a new fitting and new vent hose (after rebuilding

 

I just ordered a new vent hose and rear brake hose. Since I am currently replacing all the brake lines i figured it would be a good idea to replace these as well.