2.3L ('83-'97) crankcase ventilation

[Dennis Hudson]

Still tracking down the bugs on my 83 2.3 lima. Confused about crankcase ventilation. There is a unit that pushes into the crankcase drivers side. I think it is a separator. I routed this to a pcv valve and then to my catchcan and then to the aircleaner.
I just put a small air filter on the valve cover, but now see that oil and air are coming out of it. This cant be right.
The engine is a 2.3, completely rebuilt, with a weber and msd ignition.
I've tried to make everything as simple as possible , so all the original vacuume lines , environmental stuff is gone.
Need some advise on proper ventilation routing...
Thanks everyone for all your help. Couldn't have got this far without the Ranger Station

 

[RonD]

PCV(positive crankcase ventilation) was added to engines in the late 1950's early 1960's to reduce Blow-By emissions from exiting the engine

Blow-by is what happens each time a cylinder fires, exhaust(combustion) gases "blow by" the piston's rings and into the crank case
These blow-by gases are 800+ Degrees
Oil vaporizes at about 450deg, so some of the oil coating the pistons and cylinder walls is vaporized by the blow-by, this is where ALL the oil vapor inside the engine comes from, not from bearings or valve train

Now the crank case and valve cover areas are connected by larger oil drain back holes in the heads, so share same air space.

The Blow-by increases pressure in the crank case and valve cover areas, so in the old days there was a vent on the upper oil pan or lower block that just vented the blow-by and any oil vapor out into the air.
These vent tubes usually dripped oil

Along comes PCV system
It uses the engine's intake vacuum to pull in Blow-by gases to be re-burned in the cylinders, much like EGR system does
The PCV Valve is a reverse valve, it closes with High Vacuum(idle), and opens with Low Vacuum(acceleration)
Because blow-by is lower at lower RPMs and engine load, and blow-by is higher with higher RPMs and engine load

Problem with PCV systems is the Oil Vapor, most condenses inside the crank case since its metal parts are well under 450deg, or better be, lol
But as engines get higher miles the rings and cylinder walls get worn and, compression goes down and Blow-by goes UP
So PCV system can get too much oil residue
So catch cans are added, which is different than an oil separator

An oil separator and catch can are both used to condense the oil vapor as much as possible, before it goes into the intake
The catch can will have a removable "can" that needs to be emptied every now and then
An oil separator will have a drain that allows any condensed oil to flow back into the oil pan

Engine(intake manifold)---------------catch can-------------PCV Valve(in valve cover or crank case)

And then there is the Breather hose
Anytime you have a PCV Valve sucking air out of the engine, you need a way for fresh FILTERED AIR to come into the engine
So there will be a Breather hose on the air filter to pull IN filtered air as PCV Valve sucks blow-by air OUT

Air cleaner----------------valve cover

 

[Dennis Hudson]

Thanks . For me the key was" sharing the same air". I hooked up the catchcan to the manifold vacuum and voila, problem solved. Many thanks

 

[RonD]

Good stuff

 

[Wjstengerjr]

PCV(positive crankcase ventilation) was added to engines in the late 1950's early 1960's to reduce Blow-By emissions from exiting the engine

Blow-by is what happens each time a cylinder fires, exhaust(combustion) gases "blow by" the piston's rings and into the crank case
These blow-by gases are 800+ Degrees
Oil vaporizes at about 450deg, so some of the oil coating the pistons and cylinder walls is vaporized by the blow-by, this is where ALL the oil vapor inside the engine comes from, not from bearings or valve train

Now the crank case and valve cover areas are connected by larger oil drain back holes in the heads, so share same air space.

The Blow-by increases pressure in the crank case and valve cover areas, so in the old days there was a vent on the upper oil pan or lower block that just vented the blow-by and any oil vapor out into the air.
These vent tubes usually dripped oil

Along comes PCV system
It uses the engine's intake vacuum to pull in Blow-by gases to be re-burned in the cylinders, much like EGR system does
The PCV Valve is a reverse valve, it closes with High Vacuum(idle), and opens with Low Vacuum(acceleration)
Because blow-by is lower at lower RPMs and engine load, and blow-by is higher with higher RPMs and engine load

Problem with PCV systems is the Oil Vapor, most condenses inside the crank case since its metal parts are well under 450deg, or better be, lol
But as engines get higher miles the rings and cylinder walls get worn and, compression goes down and Blow-by goes UP
So PCV system can get too much oil residue
So catch cans are added, which is different than an oil separator

An oil separator and catch can are both used to condense the oil vapor as much as possible, before it goes into the intake
The catch can will have a removable "can" that needs to be emptied every now and then
An oil separator will have a drain that allows any condensed oil to flow back into the oil pan

Engine(intake manifold)---------------catch can-------------PCV Valve(in valve cover or crank case)

And then there is the Breather hose
Anytime you have a PCV Valve sucking air out of the engine, you need a way for fresh FILTERED AIR to come into the engine
So there will be a Breather hose on the air filter to pull IN filtered air as PCV Valve sucks blow-by air OUT

Air cleaner----------------valve cover

Thank Ron for the thorough refresher on PCV systems, plus a few things I didn't know about vaporization of oil, etc. My '97 2.3 has a pretty rusty separator attached to the driver's side engine block and I doubt I will find a new replacement, so likely will wind up at Summit Racing for an aftermarket replacement.