[THEFERMANATOR]

PCV=positive crankcase ventilation valve. It hooks into the engine(normally in the valve cover), and then to the intake. At low loads the engine is at high vacuum which pulls the PCV valve almost closed, but under load the vacuum drops which opens the valve up and allows it to pull crancase pressure back into to be burned by the engine. You must have a vent to atmosphere though for any engine even with a PCV valve. Personally why change it what you have and complicate the system any at all. It's worked this long so why change it(if it aint broke, don't fix it).