How Do You Properly Run An Oil Catch Can?

[Av8ferg]

Good discussion. Not to highjack the thread but with an EFI system would you just get rid for the PVC valve (put a bolt to fill the PVC inlet on the intake manifold) and route the crankcase vent line line directly to the catch can? Also my pipe exiting my block (on my rebuilt engine) isn’t held in the block by anything. How is the pipe fixed to the block? Here’s a pic and video.



https://youtube.com/shorts/nb9W3agy6zI?feature=share

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[AK260]

Good discussion. Not to highjack the thread but with an EFI system would you just get rid for the PVC valve (put a bolt to fill the PVC inlet on the intake manifold) and route the crankcase vent line line directly to the catch can? Also my pipe exiting my block (on my rebuilt engine) isn’t held in the block by anything. How is the pipe fixed to the block? Here’s a pic and video.



https://youtube.com/shorts/nb9W3agy6zI?feature=share

Sent from my iPhone using Tapatalk

Lemme try again without autocorrect jumble:


Not sure how it’s secured but if it’s a 22mm pipe then it’s easy to fabricate exactly the routing required with some plumbing supplies! [emoji106]

[dutchzcarguy]

16 hours ago, AK260 said:

Not sure how it’s secured

It's a press fit... once opened.... yeah your f*****  🙊

[mailnome]

I wonder if something like locktite would hold that in there well.


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[Av8ferg]

4 hours ago, dutchzcarguy said:

It's a press fit... once opened.... yeah your f*****  🙊

I’m sure someone on the forum will chime in that knows how to refit this.  I can’t be the only one that has this problem.  I imagine you can put a sleeve in there and re-press it in.  Maybe an epoxy weld like JB weld might work too.  I’d rather have a better solution that that.  Any thoughts on the PVC delete for EFI catch can.  Captain Obvious might have an answer for us.  

[Captain Obvious]

I've run into the same thing and I was planning to use the green loctite sleeve retainer. Haven't tried it yet, but I have high hopes for that. And I agree that it's weird that the original pipe was in there so firmly, but pretty much shows no retention at all when pushed back in once it was pulled out.

As for the PCV and catch can thing... With the EFI, things get a little more complicated. You need to either vent everything upstream of the AFM, or vent everything downstream of the AFM. But don't mix the two. Or vent everything completely separate from the EFI system.

In theory, PCV systems change direction depending on the engine RPM and load. So the whole notion of "inlet" and "outlet" is a little troubling for me.

At low load (low blow-by), high intake manifold conditions, the flow goes one way. But at high load conditions when the blow-by is higher and the intake manifold vacuum is pretty much non-existent, theory says that the flow direction reverses.

I guess the "normal" direction is pulled out the large pipe in the crankcase, through the PCV valve, and into the intake manifold. So if I had an "inlet" and an "outlet", I would connect the inlet to the big pipe on the crankcase and the outlet to the valve cover.

[duffymahoney]

Ok, here is my plan. It's a bit complex.  

 

Some pcv grommet from a multi pack, fits the stock check valve and block perfectly.  I might end up moving this upstream, I am a little afraid of it getting oil trapped in it.  Then BSPT adapter to hose barb.  Hose barb to a true air filtering catch can.  Catch can will be a billet version of the mann provent 100 or 150.  Filter media gets 93% of particles prior to hitting my intake.  I plan to change the filter every 1-2 oil changes.  It will mount to existing 240z holes on the fender.  Then from the filtering catch can, to the intake.  This is all just for the lower block PCV.  I haven't decided what to do about the valve cover one.  

[Av8ferg]

Duffy,
That’s a slick idea. Do you have a link to where you got that PCV grommet and valve?
Bruce., Thanks for the explanation and that make perfect sense. So keep the PCV in place to balance the vacuum pressure. I’m think the catch can can accept oil in either direction but not sure. If you had 2 inlets to the can that would function the same I think except you might suck oil back a when vacuum pressure is high in the intake. Since most modern cars using catch cans these days are EFI, I imagine there is an off the shelf solution that considers all the changes in vacuum pressure within the intake. I’ll begin my research and report back my findings.


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[duffymahoney]

48 minutes ago, Av8ferg said:

Duffy,
That’s a slick idea. Do you have a link to where you got that PCV grommet and valve?
Bruce., Thanks for the explanation and that make perfect sense. So keep the PCV in place to balance the vacuum pressure. I’m think the catch can can accept oil in either direction but not sure. If you had 2 inlets to the can that would function the same I think except you might suck oil back a when vacuum pressure is high in the intake. Since most modern cars using catch cans these days are EFI, I imagine there is an off the shelf solution that considers all the changes in vacuum pressure within the intake. I’ll begin my research and report back my findings.


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Stock PCV valve, and a grommet set from my local Napa.  That's it. I bought all they had, I think like 3 boxes of random ones.  

[AK260]

9 hours ago, dutchzcarguy said:

It's a press fit... once opened.... yeah your f*****  🙊

Surely you can flare a pipe for an interference fit and with a bit of BFI* able to make it work?

@Av8ferg - Datsun Spirit provide engines without them being in place - so worth dropping Eiji a note at how he recommends going about it.

(*BFI = Brute Force and Ignorance)

[duffymahoney]

28 minutes ago, AK260 said:

Surely you can flare a pipe for an interference fit and with a bit of BFI* able to make it work?

@Av8ferg - Datsun Spirit provide engines without them being in place - so worth dropping Eiji a note at how he recommends going about it.

(*BFI = Brute Force and Ignorance)

Boggling that his answer is just leave the vapors in the block.  

[AK260]

1 hour ago, duffymahoney said:

Boggling that his answer is just leave the vapors in the block.  

Wouldn't the block pressurise and create oil leaks everywhere?