Oily substance in Intake!

[SkyNex721]

The PCV system reduces hydrocarbon emissions by scavenging crankcase vapors. It does this by circulating fresh air from the air cleaner through the crankcase, where it mixes with blown-by gases and is then rerouted through a PCV valve to the intake manifold.

To maintain idle quality, the PCV valve restricts the flow when the intake manifold vacuum is high. If abnormal operating conditions (such as piston ring problems) arise, the system is designed to allow excessive amounts of blow-by gases to flow back through the crankcase vent tube into the air cleaner to be consumed by normal combustion.

Maybe that will explain in for you.

[Setanta]

Originally posted by civic1991
Why connect something that relieves pressure form an oil covered area to the intake which inturn connects to the manifold???

Because the easiest option is to burn the gas.

It's a relief system, not something that should run all the time. IT usually kicks in more or worn motors.

[darolh]

Skynex is correct. In the old days the crankcase vent just dumped over the side (In fact my 4 year old tractor does). The Oil filler caps were often vented to the atmosphere too. With the addition of emission controls they are trying to minimize nasty vapors coming from other parts of the engine and not just exhaust. That's why the crankcase gases are vented into the intake to be combusted and so are the fuel tank vapors.

Pure race cars don't use these gadgets as there's no smog regs for them. They use puke tanks to catch oil (and other liquids) so it doesn't get dumped on the tires/track (when the rules say you must).