Rear differential pressure build up

So i put a rear differential relocate kit on today,and when i pulled the factory breather out it was under pressure. Any one else have this, is this normal?

 

normal characteristic of truck

 

Does the cap spin on the breather

 

Probably not pressure unless you just came off of a long drive. More likely vacuum. It's a one way valve so if the pressure is equalized while hot it will be a vacuum once it cools.

 

Yes

 

Drove 60 miles

 

I would see if you cab blow through it. These things are a hold over from the early days of Toyota trucks

 

I did.it was clogged at first

 

Nope, pressure. Truck hadn't been started in a week when I did mine. Bout blew the check valve across the garage.