Oil separator anyone?

[FU]

Had them on the 441. Never had any oil in the can's when I checked. Marc Haibeck built that engine quite well.
I pullled them off after 5Kmiles, still dry as a bone.

[Schrade]

Paul...last time I checked my Elite Oil Catch Can after several 1/4 mile runs and some additional miles (I think it makes a BIG difference if you stand on it) I had maybe 1/2 inch of oil in bottom of Oil Catch Can. So it works

Is there too much oil to be filtered by some sort of added-in filter membrane? Maybe for those who don't race, like FrankU says above, and do 'hammer down' once / twice per outing, only enough to get new fuel through the secondary injectors - will THAT make for enough oil to justify a catch can?

So in the existing intake hardware, where will I see excess oil when [IF] I [ever] pull the intake / plenum ?

And since it's (+) crankcase ventilation, how does it purge, to the intake vacuum? good snappics too there...

(where is emissions routing diagram in FSM - anyone know offhand here? ) IS AIR ACTUALLY FORCED INTO THE CRANKCASE, for fumes purge??? Or is it a mis-nomer?

Hmmm... positive air pressure, into the induction.

Forced-Oil Induction?

[Dynomite]

A Brief Discussion of the LT5 PCV System in regard to the Oil Catch Can and its use.

1. CamShaft Area.
The two cam covers have a filter and air tube connected to the Air Horn. This allows dry fresh air to enter the Camshaft area venting moisture and fumes from that area. The two little restricted holes in each Head/Injector Housing entering the Injector housing (restrictions located in Head or Injector Housing depending on 90' or 91') minimizes oil and air flow going from the Camshaft area into the Injector Housing.

2. Crankcase Area.
The Crankcase is vented upward through the two large "L" hoses connecting the Cylinder Case vents to the Injector Housing Ports located under the Plenum. This allows the piston ring Blow By to be vented to the Injector Housing.

3. Injector Housing Function.
These two sources of contaminated air (contaminated in the camshaft area by moisture and piston ring Blow By coming up through the oil vents for oil to drain downward) meet in each Injector Housing.

4. PCV Valves Function (CV913C & CV769C).
All this contaminated air is vacuumed from each side of the Injector Housing through the PCV valves which restrict the flow at high Vacuum. The Vacuum is applied from the PCV connection on the front of the Plenum behind the Throttle Body. At Idle, Plenum Vacuum is high and the PCV valves close down a bit. At lower Vacuum when the Throttle is open (higher Crankcase Blow By) the PCV valves open up a bit more. I am thinking if you have excessive piston ring Blow By more than the PCV vacuum can handle through the Plenum, that excessive Blow By would be forced in reverse through the cam covers to the Air Horn with oily fumes captured by the Cam Cover Filters.

5. Summary of PCV System.
In Summary, the contaminants from the Crankcase and Camshaft area meet in the Injector Housing and are vacuumed through the PCV valves. Fresh air picks up moisture by passing through the Camshaft Area and Crankcase Blow By contaminants from the crankcase are both vented to the Injector Housing.

6. Oil Catch Can.
Both contaminated air sources pick up oil fumes on the way to the Plenum which fumes are liquefied and caught in the Oil Catch Can installed on both my 90' and 91'

If you have no Oil Catch Can and a bit of Blow By like most higher mileage engines (Frank has a tight rebuilt from bottom up engine I am thinking) the oily fumes continue on into the Plenum exactly as Paul describes

Originally Posted by Paul Workman

Oil, not separated, makes its way to the combustion chambers, fouling plugs, carboning up the valves, contributing to knock, plugging the MAP sensor hose (leading to other seemingly disassociated issues with idle and AF mix...) Not good. The LT5 (among other open deck motors) is prone to a little more crankcase pressurization - hence oil blow-by - than some others (tho some LS motors also have oil separators for the same reason: keeping oil out of the cylinders).
P.

6. Charcoal Canister and Purge Vacuum.

The Fuel Tank Fumes Purge is a separate issue. On the 90' the charcoal canister is under drivers side headlight. On the 91' the charcoal canister is behind passenger side rear wheel well. The charcoal canister captures fuel tank fumes through the Purge Vacuum System (a minor difference between 90' and 91' Plenum connections). There is a Purge solenoid under the Plenum for 91' and under drivers side headlight for 90' that controls activation of the Fuel Tank Purge System.



Notes:
I highly recommend Jerry's new PCV valve rubber hose which solves the issue of the vacuum leak from the plenum to the PCV system.

You can see the size of the PCV Connector openings (Jerry's new on left and old on right in each photo). Replacing these with Jerry's NEW PCV top connector (on left in each photo) is a must.

Jerry's Dual PCV Valve Connector

Old PCV Valve Connector on right.........................................New PCV Valve Connector on left


I also highly recommend Marc's Camshaft Cover Filters if you remove your Cam Covers for any reason.