Vent or Valve in Valley of Block?

[HOdbleFman]

What is the black rubber plug in the valley of the engine block? It is located near the thermostat housing and has a rubber hose connecting it to the intake manifold. Is it just a crankcase vent? Does it ever need replaced?

 

[FE 065]

It's your PCV system, at least it is on m 2002. Engine vacuum pulls crankcase vapors out of the engine through that hose and into your intake manifold. The air in the crankcase is replaced by air coming into the crankcase through the hose on the left side airbox, into front of the valve covers, then down the crankcase in a continuously recirculating system.

There's nothing in there to wear out basically.