PVC mod questions

[thealleyboy]

The car is an 87 EA82 {carbed} D/R wagon. Nearly all of the OEM emissions equipment has been eliminated, and I'm down to the PCV system.

I'd like to install one of the round aftermarket "universal-type" air cleaners for simplicity. The air cleaners I've looked at have a single knockout for the PCV. However, the PCV systems on our Subes require 3 fresh air ports (PCV, crankcase inlet, crankcase outlet).

I'm trying to decide how to deal with the crankcase ports. Some sort of "breather valve" would seem to be the ideal solution - if such a valve even exists.

Other possibilities (in order of desirabilty) are:

additional ports on the air cleaner

bypass hose from inlet to outlet

caps for inlet and outlet

total elimination of the PCV

Any suggestions/ideas ?

thanks, John

[1 Lucky Texan]

The car is an 87 EA82 {carbed} D/R wagon. Nearly all of the OEM emissions equipment has been eliminated, and I'm down to the PCV system.

 

I'd like to install one of the round aftermarket "universal-type" air cleaners for simplicity. The air cleaners I've looked at have a single knockout for the PCV. However, the PCV systems on our Subes require 3 fresh air ports (PCV, crankcase inlet, crankcase outlet).

 

I'm trying to decide how to deal with the crankcase ports. Some sort of "breather valve" would seem to be the ideal solution - if such a valve even exists.

 

Other possibilities (in order of desirabilty) are:

 

additional ports on the air cleaner

bypass hose from inlet to outlet

caps for inlet and outlet

total elimination of the PCV

 

Any suggestions/ideas ?

 

thanks, John

 

I forget what they call them, but the tuner/modder guys have some 'breathers' they sometimes put on Soobs. (there are a 2-3 or more places that require them on modern engines). They sometimes fit oil catchcans too. I dunno much about 'em. If someone can't help, maybe you could try a search over at www.nasioc.com

[TomRhere]

On mine, I ran a length of 5/8" heater hose from the PS valve cover up behind the strut tower, put a small air filter on the free end.

 

Length of same size hose from DS cover up to strut tower, install the factory "T" fitting run more hose back to PCV valve, then a smaller hose from "T" to the air filter on the carb.

 

 

Ran hoses from valve covers up to the strut tops to try to eliminate the "oil smoke on hard turns" thing. Seemed to help. Did this on both EA-81 and EA-82 carbed models running a Weber.

 

You can delete the smaller hose back to the intake filter, but the PCV system really needs to have a second means of pulling the crankcase fumes into the intake to work properly,(mostly for wide-open-throttle (low vacuum) times), hence the line to the air filter on the carb, (intake tube on FI models).

[thealleyboy]

Thanks for the info Tom. I'll give it a shot. I'd really like to go with one of those aftermarket air cleaners for better breathing.

I did talk to a guy at a hi-po shop that recommended a universal breather valve that can be installed right at the valve cover. Only problem is that they are larger than the 5/8 diameter inlet on the Subes, so some step-down mods would be necessary to install it at that location. They are also kinda expensive...

 

John

[Handtool]

I'm getting ready to rework my PCV system as well. Here is what I have planned:

 

Tom, (or anybody else) are you saying I need a filtered air source somewhere between the PCV valve and the valve cover for the pcv valve to function properly?

[thealleyboy]

If I understand the system correctly, the PCV is supposed to recieve a mixture of fresh and bypass air. The fresh air may simply be to "balance" what is being expelled on the opposite side (all bypass). That is why you cannot just run one side of the crankcase into the other, and just draw straight filtered air thru the PCV. You need a way to release the dirty air from the crankcase.

Someone correct me if this is not the way it works...

John

[Snowman]

You're correct. The whole point of the PCV system is to suck the vapours from the crankcase. The picture that Handtool posted is exactly what you need.

[Snowman]

Whoops, accidentally double posted.

[TomRhere]

Basically, the PCV system needs to be able to breath to do it's job correctly. If you look at the "stock" set-up, the PS hose is plumbed into the air filter housing "inside" of the air filter element. The small line from the "T" fitting is plumbed into the air filter housing "outside" of the air filter element.

There is a difference in the amount of vacuum at both PCV hoses in the AF housing, coupled with the amount of vacuum at the PCV valve itself. This difference allows the fumes to be sucked into the intake manifold at the PCV valve where it is mixed into the charge for the cylinders, drawing in air thru the PS valve cover, out of the DS cover then thru the PCV valve.

Now, at "wide open throttle", the amount of vacuum at the PVC valve itself, drops, air flow thru the PVC system actually reverses if you will. Air is drawn-in thru the smaller hose, thru the "T", into the crankcase thru the DS hose and out the PS hose into the filter housing then thru the carb. That is why one finds oil in the filter housing at times, Subaru could have done a better design on the seperators found inside of the valve covers, would maybe stop some of the oil migration, (and is why one gets that "oil smoke on hard turns" thing.

[MorganM]

Mine is pretty simple. Both rocckers go upto a T splitter. Single hose out of the T splitter to a generic breather filter. Can be found at most parts stores. Then I plugged the PCV valve hole in the intake manifold with a bolt that had the same diameter and thread pitch. I think it was a bolt from some part of the rear suspension; not sure I just grabed it out of my spare Subaru hardware box.

 

I know all the theories behind how it should properly work. Thats all well and good but I dont like squirting nasty, oily, air down my intake and into my combustion chambers. Crankcase vents just fine out the setup I have. I can tell becuase the filter oozes out plenty of oily muck. The filter is tucked down by the hill holder so it doesnt ooze all over the engine bay.