How much blowby is "normal"

[daschrier]

First post, not sure if this is the right section...anyway.

I have a 2004 sentra 1.8
Everyone pretty much knows how the pcv system works, fresh air into the valve cover/crankcase, blowby out through the pcv and into the intake manifold.

Last few times I've cleaned my CAI piping, there has been some oily residue in the piping, probably from blowby. Most people I talk to say this isn't normal, and that it shouldn't happen with a correctly functioning pcv system. However, in the FSM for my car, it states that under full load and acceleration, vaccum by the intake manifold isn't enough to completely remove all the blowby build up, so gases escape back out of the valvecover side of the pcv system and into the intake.

Since this system was designed this way, is there anything I can do to keep crud out of the intake and from gumming up the TB...maybe an inline fuel line filter?

 

[JTK]

Is it a 5spd? Do you do a lot of WOT between gears? Some oil from the breather sounds normal.

Joel

 

[Master ACiD]

fuel filters are not designed to filter oil vapours from air. fuel filters (in the typical sence) are designed to filter solid contaminants from fuel.

 

[daschrier]

Yes it is a 5speed, and I drive in stop and go traffic every day (Boston), so I do rev up a lot. I wouldn't actually put a fuel filter in the line, just wondering if there was something I could use to catch the oil, unless it's not that big of a deal then I won't worry about it. One of those things you probably wouldn't care about until you notice it, then you get concerned

 

[robbobster]

You can just use a common separator:

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=24;t=002301

 

[Chris142]

Don't forget that when vacuum drops the PCV valve will shut...........Then the vent hose will allow the vapors to be sucked into the intake.