Diesel Models: 190D
The system consists of an oil separator located under valve cover, distribution tube on intake manifold, and return flow tube. California models are equipped with a diaphragm regulating valve located in the oil separator.
When the engine is running, blow-by gases flow through the oil separator, through a connecting hose, and to the distribution tube on the intake manifold. Oil from the separator returns to the cylinder head through the return flow tube.
On California models, the diaphragm regulating valve is used to prevent excessive vacuum from forming in crankcase.