Positive Crankcase ventilation

[GeoffM]

Could somebody enhance my knowledge?
I thought that the PCV valve was supposed to put a negative pressure on a neutral crankcase. I had my PCV out while my engine was running, and felt air being blown out. Does this mean my rings are going bad? Or is it this way with everybody?

Side note: There is no PCV grommet in my car. I drove for a few miles, but it worried me. Online, all the local autoparts stores need to order them. Lets say it takes 2 days, can I drive without one?

[accordztech]

The Pcv system is designed to recycle blowby back into the intake manifold. At idle the pcv valve is operating and recycling blowby. While driving the pcv valve doesn't work however the other line that goes into the intake from the valve cover is venting the blowby gas back through the intake pipe/throttle body.

It is OK to run without a gromet for 2 days. Some guys run them with a filter on it to vent into the atmosphere. I personally don't do that

As for negitive pressure in the crankcase its a little more complicated. Less than atmospheric pressure in the manifold is caused by the itake valve and the piston on the intake stroke. Since the throttle body is closed it creates a vacuum less that atmospheric pressure. This is what creates vacuum.

I may be only 95% correct.

[Fleetw00d]

Any airflow past the throttle plate results in some pressure loss, so the pressure in the plenum will always be at least slightly less than the pressure in the intake duct, so theoretically blowby gases will always be drawn through the PCV hose. The hose to the intake duct allows the PCV system to pull filtered air into the crankcase so that the intake isn't pulling a vacuum on the crankcase when the throttle plate is closed. If you have a lot of blowby, it may overpower the PCV system and blow back through the line to the intake duct.

In the end, you are correct, running without a grommet probably won't hurt anything except maybe make an oily mess.