Just thought I would check the rear diff. It was a bit low from the factory. When I opened the fill plug it made a vaccum hiss Is this normal? the front one didnt do it. When I check my trucks diff it dont do that. Do you think the diff bellows are working propery Thanks your replys would help.

 

It should be vented, so look for a pluged vent line.

 

mine does it too, it isnt a vacuun its a bit of pressure. Its just because the bellows contract back to there normal relaxed size when there is an escape path for the pressure

 

DA, stupid me I never thought of that. I checked the rear bellow last night is is behind the fuse panel everything was ok. Now you mention that it makes sense. Thanks Peteyz24 also thanks for the reply Hondabuster.

 

Arctic Cats differitals are not vented, that is why they use bellows. Normal for you to hear a hiss depending on pressure or vacumn in diff when temps change.