Subaru PCV system diagram

[vik]

Hi,

I was hoping that you Subaru experts out there might give me a hand.
My PVC system is not connected properly. I tried to find a proper routing in a manual, but was not successful. I found following diagrams:

My PCV valve is located in the intake manifold as some of the later engines have it in the block.
If this is correct than from intake there shall be breeders to each cylinder head.
And one which merges with breeder exiting left side of the block (looking from behind Vanagon) and is connected to the PCV vale in the intake manifold.

Is this correct?
Maybe anyone have some actual house routing diagram?
This is closest I could get

pls ignore 4+5 as this is only for ECU
9 (PCV) is on the other side of #1 tube.

Any feedback welcomed
_________________
T3 Syncro camper in progress

[Mikesarge]

You’re correct. The pcv valve operates to allow positive crank case pressure to vent back into the intake, From the heads and case, you’ve described it correctly. I’ll try to take some photos of my ej22 PCV system tomorrow if that’s helpful
_________________
1986 Syncro westfauxlia EJ22
1980 911 SC 3.1

[11BC2]

OP:

What Subaru engine are you using?

[vik]

[wesitarz]

My 02 2.5 has a hose from the crankcase left side that goes to the PCV valve in the manifold. There is a 'T' connection that goes to the intake. There are two hoses from the valve covers that go to the intake.

[vik]

[Sodo]

(will re-post later so wesitarz can finish his assistance)
_________________


'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[wesitarz]

I should clarify, this is the way I hooked it up years ago. I have an early intake from a Legacy or something. It has 2 ports on the underside. The 2 breathers from the valve covers connect together and Tee to one intake port. The other intake port connects to a Tee in the hose between the crankcase and PCV in the manifold. That seems to jive with your diagram.

Currently the hose from the crankcase loops to an oil catch can then back to the PCV valve.

[Sodo]

Sorry this isn't directly to your question, but something to consider as you work out your Subaru PCV.
You don't wanna build an oil-drinker if you can help it.
Here's a related Subaru PCV system note that you might consider.

===========

Oil consumption is a real concern with Subaru powered VWs.
The duty-cycle asked of the engine is extreme in comparison to its former life.
The engines appear to be tough enough, but the RPM and HP output conditions have changed.

Pushing the shoebox they run at a higher-power position in the torque curve.
RPMS higher, torque higher, piston-distance traveled is farther.
The pistons & rings travel much more distance than scooting that slippery little sedan in top gear.

The engines were probably not designed to operate at such high RPMs for long periods, 'cuz the little car would be going 100mph.

Possible the PCV system is not designed for the vanagon duty-cycle, the sustained high RPM, high power output.....

The higher RPM for long periods perhaps overwhelms the systems capacity to control its ventilation system oil.
Look at the baffling system Subaru used to let the oil settle, cool, and rest, it's extensive.
And the oilpan was deep.
The oil had time to relax, rejuvenate, let bubbles out, shaded from the radiance of hot pistons etc.
I doubt Subaru did all that sheetmetal monkeybusiness just to throw a bone to their metal-stamping suppliers.

And there are resonant-cavity issues of the crankcase volume that are perhaps not optimal for the (much) higher RPM than soccer-mom uses in her Forester.

===============

Vik, note that none of your diagrams show how Subaru damped the crankcase pressure pulses.
Subaru piped the system to below the oil level, not open to the pulsing crankcase cavity.
The PCV system oil drain, sealed off from the crankcase pulsations by the mass of the oil insulates crankcase pressure pulses from the PCV system, letting the various valves operate undisturbed..

I had a Subaru pan (by Outfront motorsports) that had retained Subaru's below-oil-level venting.
But my van drank oil back then too, dangit.
I changed to a Smallcar oilpan with an additional 1qt of oil (25% more).
It seems to run longer on a batch of oil before it starts to gulp it.
Which I attribute to the simple fact that there's 25% more oil.

I think some of the baffling needs to be restored.
I have a KillerB windage tray, but Mr Fuji put in a lot more sheetmetal than that.

At the least I'm planning to adapt the sealed oil-pipe tube from the old pan if I ever take the Smallcar pan off. (but not soon)
_________________


'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[kalispell365]

[tates1882]

[Sodo]

[kalispell365]

Thanks Sodo!
_________________
1983 Diesel Vanagon Westfalia chassis with Subaru 2.2l

[Sodo]

I had to remove my cast oilpan to change the Longblock
I don't know why (yet) but at 81k miles #2 cylinder showed 30psi.
And some chunk closed the sparkplug gap, breaking the insulator.
I just put in a 2011 JDM long block from Foreign Engines in Lynnwood, WA.
It's bolted up as of last night.
Today I'm attaching hoses, muffler rebuild etc. Wish me luck.
The Forest air is clean again.....I want to CAMP!

OK enough of that (off-topic).

====== Back to PCV system =========

Here's how I restored the calm-air drain from the Oil Separator cavity.
Does anyone know why the aftermarket oilpans would omit this feature from the (highly engineered) PCV system?
This oil drain that uses the oil mass to insulate the PCV valve from crankcase pressure vibrations is used on every EJ motor since the beginning of time.

Is there a 'reason' to omit this part of Subaru's engineering?
Or was it just a brain fart? (co-fart by pretty much "all" aftermarket oilpan producers?).

It seems reasonable that at some RPM, the crankcase pressures could flutter the PCV valve poppet.
And we are running these engines at a different sustained RPM than Subaru did - pushing their slippery little sedans.
Perhaps the PCV system is not optimized to run at steady 3600RPM (65-70mph) on the freeway.
And as blowby increases with age, theres more/higher crankcase pressures/pulses etc.
_________________


'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[Jake de Villiers]

Hey mister, how much was that JDM engine? Did you re-do the head gaskets and check the rings or just cowboy it?
Enquiring minds need to know!

I also find it weird that guys like SmallCar completely ignore the OEM baffles in the bottom of the pan. It must have to do with not having to warranty the engine...
_________________
'84 Vanagon GL 1.9 WBX
'86 Westy Weekender Poptop/2.5 Subaru/5 Speed Posi/Audi Front Brakes/16 x 7 Mercedes Wheels - answers to 'Dixie'
@jakedevilliersmusic1
http://sites.google.com/site/subyjake/mydixiedarlin%27
www.crescentbeachguitar.com
www.thebassspa.com

[Sodo]

I need to stay on the PCV system topic that Vik is working on.
_________________


'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[Phoxxanator]

[Sodo]

That's a great suggestion...but I've adopted this unorthodox oil-control mod 'between engines'.
I don't have any before/after data.

Someone who has a running EJ with the calm-oil-drain could perhaps do a before/after for us?

It might be a difficult test.....Flutter would be a resonance condition,
a fleeting condition.
The PCV valve poppet could flutter only at some specific RPM and loading.
Or some blow-by condition at later engine age. etc etc.
or.....if it flutters at all

This is just a theory, and a wild one at that.

Note KillerB's aftemarket oilpan omits the sealed oil drain of Subaru's air-oil separator,
and offers 'additional' aftermarket separators.
I'm curious what was KillerB's reasoning to omit a crankcase oil-control feature that Subaru has added to every EJ for 30 years.
Maybe they are basically omitting the Subaru separator as being 'too small' etc and replacing it with a bigger one for higher RPM and sloshing, turbo crankcase pressures etc. (racing)
Gotta wonder too if all the other oilpan producers are just blindly copying other producers who have omitted the sealed drain.

Where omitting the sealed drain then requires a larger oil separator?

Agreed racing/rally cars and RV usage could have have synergies but each crossover mod should be examined on a case-by-case basis.
_________________


'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[Syncro Jael]

Sodo, a couple thoughts I have.

When my EJ22 had a ringland failure it was blowing oil out both the valve cover hoses into the intake. This is backwards of the airflow of the diagram shown above. I always noticed that my intake hose was wet on both previous EJ22 engines. This was coming from the valve cover breather hoses.

Now I have added a large Radium air/oil separator that "tees" both of those breather hoses and back to the intake. I have noticed earlier in cold winter months that catch can will produce a substantial amount of milky oily mixture. During the summer there has been nothing in that catch can.

I also have another Radium air/oil separator that comes from the PCV hose on the top of the block, through the catch/can then back to the PCV valve and intake. This catch can creates much more milky oily mixture than the valve cover breathers in the winter. Summer driving it very rarely has anything in it and if it does it is not milky, just nasty smelling oil.

I do not have to add any oil between 3000 mile oil changes. In fact it does not use any discernible amount of oil.

I have the RMW pan, EJ25 Hybrid with EJ22 heads, KEP conversion, and use a full 5 qts of Mobil1 0-40 Oct-May and Mobil1 20-50 June-August.
_________________
1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat)

[Sodo]