Blown out, yeah you need to check that rear axle vent.
If the vent has a hose, check the end of that, because those dirt dobber bees just love a small hole like that to build their nest in & then the rear end cant vent off the pressure once hot.
Maybe check where the hose goes through something, like a pull tye holding a bunch of hoses, wires & tubes together. Ol hose get hot & close up & then not vent.
Neil