axle breather blocked?

[sid1]

i went to change my rear diff oil today when i released the filling nut there was a distinct whooze of air as if it was under pressure. is this normal or do i have a blocked breather.if so is it just a case of removing it and cleaning

[Albannach]

I don't think you'll be successful cleaning it, I'd just replace it.

It's a one way valve, by the way, it lets air expand outwards but won't allow it back in. Are you sure it was a positive pressure you felt?

[sid1]

not sure as to wether positive or negative if its blocked shouldnt it be a positive gush. just remembered i did have a leak of diff fluid onto rear brake drum sometime back which has resolved

[Albannach]

not sure as to wether positive or negative if its blocked shouldnt it be a positive gush. just remembered i did have a leak of diff fluid onto rear brake drum sometime back which has resolved

If the diff is hot and the breather is blocked, there will be a positive pressure; if it's working properly and the diff is cool (and all the seals are sealing) there will be a negative pressure. If it's failed completely, the pressure will be equalised, so no sook or blow when you remove the plug.