Strange Crankcase Ventilation

[Dave WM]

I would forsure either get it back to working as designed OR use the open vent. that half way approach just messes things up as ZH  note with oily by products.

[siteunseen]

Here's the latest routing too.  1978 changed to this...

[moozieman]

14 minutes ago, Dave WM said:

I would forsure either get it back to working as designed OR use the open vent. that half way approach just messes things up as ZH  note with oily by products.

I was under the impression that the engine would not run with an open valve cover. Isn't that a vacuum leak?

[siteunseen]

Here's the recall explaining it somewhat.  Wick Hubble's book explains in depth, page 194.

https://howtune.com/recalls/nissan/280z/1977/

[siteunseen]

3 minutes ago, moozieman said:

I was under the impression that the engine would not run with an open valve cover. Isn't that a vacuum leak?

It'll run but lumpy like when you remove the oil filler cap while running.

Yes, vacuum leak.

 

Edited April 8, 2020 by siteunseen

[moozieman]

2 minutes ago, siteunseen said:

It'll run but lumpy like when you remove the oil filler cap while running.

Yes, vacuum leak.

 

So my question.. Why would I want to run it open like dave suggests? and how should I go about removing that cap and getting that pipe back on? Is the hole threaded?

Edited April 8, 2020 by moozieman

[siteunseen]

I have mine done similar to the '78s so I can't say.  I only see those valve cover filters on 240s but I have read about closing all that up and using the small filter.

[Zed Head]

4 minutes ago, siteunseen said:

It'll run but lumpy like when you remove the oil filler cap while running.

Yes, vacuum leak.

Not with the bottom hose disconnected.  There's no opening to the crankcase with the bottom hose plugged. They run poorly because the air gets sucked through the crankcase, through the hose, and through the PCV hose.

[Zed Head]

5 minutes ago, moozieman said:

So my question.. Why would I want to run it open like dave suggests? and how should I go about removing that cap and getting that pipe back on? Is the hole threaded?

Most of your questions are answered.  The plug looks like a core plug.  With a closed system you'll gum up the intake system.  Etc.  Absorb....

One way to remove a core plug is to tap one side inward.  The other side will pivot outward and you can grab it with pliers and yank it out.

[moozieman]

8 minutes ago, Zed Head said:

Most of your questions are answered.  The plug looks like a core plug.  With a closed system you'll gum up the intake system.  Etc.  Absorb....

One way to remove a core plug is to tap one side inward.  The other side will pivot outward and you can grab it with pliers and yank it out.

Yep. I think that answers everything. I just recently found out about that plug and up until this point have had the system "closed" with the stock hose setup and everything. I essentially need to pick one way or another- the stock setup with the crankcase breather + pcv OR have a breather filter on the valve cover and eliminate the pcv. Yeah? Any potential blowby can still be caught?

Edited April 8, 2020 by moozieman

[siteunseen]

If your as bored as I am here's a good read.  Check out the attachment too, CCV Bible.

 

[Zed Head]

Does the engine have a lot of miles?  If you have high blowby you might blow oil out of a little breather filter on the cover.

It will probably run fine just like it is.  The inside of the intake system will just get oily and messy.  I'd just put it back together and think about it for a while.  It won't hurt anything to leave it that way. You wasted money on that PCV valve though, it's not doing anything.