280 Models With Vent Jet

System consists of a sealed oil filler cap, a vent jet in camshaft housing, and a hose connecting either air filter, or purge port to cylinder head cover.

The engine blow-by gases and crankcase vapors are routed from the cylinder head cover to the idle air duct in the intake manifold via the vent jet. From this point gases flow through the intake manifold to the combustion chamber.

In the lower and partial load range, intake manifold vacuum draws clean air from the air filter through the air hose connected to the cylinder head cover, picking up blow-by gases from the engine along the way.

In the upper load range and depending on the blow-by volume, blow-by gases and crankcase vapors also flow to the clean side of the air filter. Together with intake air, they flow via the air flow sensor and intake manifold to the combustion chambers.