Is this how Positive Crankcase Ventilation works on the Z22SE?

Berto

(Apologies if this is well known old news for many of you guys, but I'm new to fiddling with this particular engine ).

This is how I believe it works , please feel free to correct me if I'm wrong.

· There is no PCV valve on these engines.

· Fresh, filtered air from the intake manifold goes into the crankcase thru 'A':

(I believe 'b' and 'c' have no role here, correct me if I'm wrong)

· Ventilation air then goes upwards thru the block and cylinder head and reaches the camshaft cover thru the 'E' passages:

· Ventilation air then exits the camshaft cover thru 'G':

· Ventilation air is finally drawn into the Airbox -> Throttle Body pipe thru 'J':

Did I got it right?

Berto

Some corrections:

· There is in fact a check valve inserted into the intake manifold, between ports 2 & 3 (the rectangular lighter-coloured thing):

. . . .

This valve comes included with intake manifold gasket replacement kits.

A royal PITA if you ask me, for you need to take apart the intake manifold just to check or replace this frigging valve. That sux big time.

· The hole in the cylinder head between intake ports 2 & 3 leads to a passage that goes UPWARDS to the camshaft housing area thru 'F' (not downwards to the crankcase):

** Note: In this particular cylinder head the passage has been blocked with black paste*

Berto

Now here's a superb video on how this style of Positive Crankcase Ventilation system works. The engineer explains the Toyota 2ZZ on board Lotuses, but what he says is (I believe) directly applicable to the Z22SE:

https://www.youtube.com/watch?v=vabonLBYx9s

· Toyota thicker hose from cam cover to pre-throtlle valve == Z22SE hose from cam cover to the airbox ·> TB pipe, pre-throttle valve

· Toyota thinner hose with check valve from cam cover to post-throttle valve == Z22SE passage from cam cover ·> cylinder head hole between 2 & 3 intake ports ·> check valve ·> intake manifold, post-throttle valve

Berto

Hmmmm ... is this thing actually a check valve ...

. . . .

... or just a plain and simple metered orifice?

evocarlos

the z22se is n/a so no need to have a oneway valve the inlet is always in vacuum
the rocker cover is split into to halfs i did have the pics but not on the laptop
@[deleted] did some mods and im sure theres some of his pics of the inner covers removed with the oil separators in place

Berto

evocarlos said:
the z22se is n/a so no need to have a oneway valve ...

Murphy's law:
*

"... A second function of the PCV valve is to protect the engine in case of a backfire, which causes a sudden high-pressure pulse in the intake manifold. This forces the PCV valve closed so that the backfire flame can't reach the crankcase, where it could ignite flammable fumes and cause damage ..."

https://en.wikipedia.org/wiki/Crankcase_ventilation_system#PCV_valve_or_orifice

evocarlos

You would only need a check valve on a boosted engine hence why the pic above of mine you used where the pcv is blocked with rtv to stop blow threw in to the rocker cover during boost
I don't know murphy or his law but I know how the z22se pcv system works and the z20net 😉

evocarlos

Also if you look on the right side of the inlet there is a blow off valve in the event of backfire...

Berto

evocarlos said:
... the pic above of mine you used where the pcv is blocked with rtv to stop blow threw in to the rocker cover during boost ...

BTW after blocking that passage how does that engine vent crankcase when off boost?

evocarlos said:
Also if you look on the right side of the inlet there is a blow off valve in the event of backfire...

Yep that's a nice touch:

I've seen throttle bodies being blown off intake manifolds by backfire, that's why I'm a little apprehensive about TB bolts tightening torques and check valves.

corsaZ22se

crank case vents to the inlet before the throttle body or as some people do to atmosphere/catch tank, this goes for n/a and forced z22se's. 🙂
unlikely you will get back fire's on modern engines with all their electronic's to prevent it. unless something is seriously wrong? :confused::eek:

evocarlos

as dave said the cover is still vented to the inlet so all of the pcv function is moved to the intake pipe
its more likely the inlet would split in half before the t/b came off if backfire was ever the case if it is you shold see about getting the cam timing sorted lol 🙂

evocarlos

red area is from the block and vented to inlet before t/b
yellow area is from the cover vented to the inlet manifold thru the pcv valve
all goes thru oil separators to catch the oil sprites to retain as much oil as possible

adams pic i edited could not find the others i did ages ago

Berto

corsaZ22se said:
crank case vents to the inlet before the throttle body or as some people do to atmosphere/catch tank, this goes for n/a and forced z22se's ...

evocarlos said:
... the cover is still vented to the inlet so all of the pcv function is moved to the intake pipe ...

Personally I want both PCV lines (pre and post throttle plate) operational at all times. And I want my check valve on the post throttle plate PCV line. Regardless of NA, SC or turbo.

Food for thought

corsaZ22se said:
... unlikely you will get back fire's on modern engines with all their electronic's to prevent it ...

^ Exactly my thoughts right before that TB entered Low Earth Orbit. Damn be Murphy.

evocarlos said:
red area is from the block and vented to inlet before t/b
yellow area is from the cover vented to the inlet manifold thru the pcv valve
all goes thru oil separators to catch the oil sprites to retain as much oil as possible

adams pic i edited could not find the others i did ages ago

^Thanks for the pic and explanation Evocarlos.

Here are more pics of cam cover innards (L61): http://www.j-body.org/forums/read.php?f=40&i=185338&t=185338

I hate riveted cam cover baffles , no way of cleaning them without lots of extra tinkering.

evocarlos

Ive fitted the b207 head and the supercharger inlet pcv valve now lines up
with the l61 head and the lsj inlet the pcv hole and valve don't line up that's why it was blocked off or you get oil running down the back of the inlet since then we have started to drill a hole 45* to link the pcv hole to the valve on the 2.2 supercharger conversion
The lsj valve and z20net are one way so they're shut during boost
Don't want any of that 22psi getting to the engine lol

dewismotorsport

Sorry not been online for a while. As Carl says there are pictures of my mods to the breather system in my build thread.
My pcv is blocked off and all breather pipes will be going to a 3 litre catch tank.

Berto

OK, suspecting that my engine was needing it badly, and inspired by the example of Dolby and other enterprising Z22SE / L61 owners , I've bypassed the post throttle plate PCV line.

For a start I've fitted 3.5 mm Ø barbed fittings:

. .

The effects have been instantly noticeable, engine feels more "free breathing" and responsive, and revs happier.

Idle has not been altered, ticks stably at the same rpm & l/h than before.

My conclusions:

1) The frigging metered orifice between intake manifold ports 2 & 3 is partially obstructed / totally clogged up (courtesy of 15 years of crap dumped inside the intake by the EGR ), and/or it can't cope with the amounts of blow-by from this relatively high mileage engine (193K km ~ 120K miles).

2) Engines love crankcase vacuum with a passion.

Next I'm going to experiment with thicker 5 mm Ø barbed fittings and some PCV valve (that functions like a variable size orifice, smaller Ø at idle, larger Ø at WOT) ...

... . from another engine of similar displacement.

Would love to tinker with an adjustable PCV valve, but they aren't cheap.

Berto

A PCV joke :

I've got such a strong vacuum through the oil fill tube that you can hardly get the cap off and it will suck your hand to it. What is going on?

How did my ex wife get in there?

corsaZ22se

if you want vacuum in your crankcase why not fit a vacuum pump like BMW do on their high revving n/a cars so the dirty air does not go back into the intake manifold without first being filtered?
my z22se pcv was clean all bar some oil staining after 117,000 miles, as was the rest of the engine.

Berto

^ The vacuum pump in valvetronic bimmers is for the brake servo, not for crankcase ventilation. (They need it because valvetronic dispenses with conventional throttle plates. No throttle plate = no vacuum inside the intake manifold, like in diesels).

There are vacuum pumps specifically designed for crankcase ventilation, but that's hardcore stuff tailored for balls-out racing cars. Grossly overkill for my application, a daily driver for the street.

Besides I already have a free source of vacuum inside the intake manifold downstream from the throttle plate, plenty enough for the task.

Oil contamination in the intake can be minimized with 2 catch cans, one on each PCV line:

https://www.youtube.com/watch?v=Zo4SltHUGd4

And just for the record , leaving aside the crap inside the intake manifold courtesy of the now ostracized EGR, my engine isn't too dirty:

. .

corsaZ22se

i'm not talking about the BMW brake servo pump. they also fit a vacuum pump on the M3 evo and other models.