The first VWs (and Porsches) had dirty-air heat-- the 1950s sealed, 'fresh air' heater-box was a big step forward (and I patched many a Boston-area heater box on split-window vans in my relative youth), well before our Type IV motors came into being. I have a problem, enabling my dual carb-fitted (Webers; the p.o. did it-- it would not be my choice) 2.0 liter to mimic some of these earliest VWs: rapid build-up of dirty deposit on the windshield above the defrost vents and hydrocarbons in the pass. compartment air-- un-noticable in the warm weather, tolerable with the windows open, but a drag- and presumably a health risk- when the windows are up and the heater or esp. the defroster needed. The boxes are like new, and the joints all along the way are all snug. The problem is two different small breathers on the top of the engine, one a couple of inches (center to center) of the oil filler tower, the other about 3 1/2 inches toward the driver from the filler, which is one of three hoses running off a fitting, the other two of which disappear into the sheet metal of the cylinders-- one to each side. Both the short woven- cloth wrapped flexy- tubes coming up from these points are currently capped by what appear to be mini-air filters-- round, well over an inch in diameter and not much taller. Both display wire around their open circumference, possibly hiding other filtering material- can't tell.
SO, my Q's are: Are both these breather-like elements under positive pressure from the crankcase--suggested by the fact that a cleaned engine compartment will be well-bathed in oil after a modest run at near 100 mph-- and more gradually under more relaxed driving? IF so, is there a place on a carbed car for these to disgorge their effluents into a closed loop as in the original FI design. (Or is one positive pressure, the other neg? -which, if so?)
Help me, Obi-wan Kenobi, or anyone else who knows how to channel the hydrocarbon force.

The valve covers run about 1/2 full of oil. The breathers on the heads are going to suck some, which is why VW or Porsche ran the hoses to an anti-flash back valve and then to the aircleaner (suction).

The engine produces pressure from leakage past rings and the whirling crank assembly.

All those lines are under positive pressure due to ring leakage and valve guide leakage. I've got the same problem, with all those lines going to a single breather box. I was preparing to attach a fitting to the air cleaner top to connect to a similar fitting on the breather box when I realized the rain tray would be in the way. I drive in the rain enough to make that a must-have, so now I am stuck with a filmy windshield. Have you done a leak-down test to see how bad the losses are?

Run 'em into the air cleaners like nature (and the federal gummint) intended. Open crankcase breathers have been illegal in the USA since 1965. The Cap'n

Thanks; that sounds good: I have K&H air cleaners on the dual Webers. What do I do-- drill a hole in the top chromed covers of the cleaners? And put the hoses in how? On one or each to its own side?
And, since that's the one closer to the driver, there's the other one. What about the other--on the passenger side, without the hoses?

I've got the same exact situation.......

you can find elcheapo plastic fittings with threads on one side at homedepot to put in the filter tops. if your heads have the little return tubes, the basic aluminum foam element filled breather boxes will work with a little maintenance. mount it high enough to allow for the hoses to run downhill.

ok, but isn't that what the cap'n refereed to as being illegal?
i have a breather box setup and my heat (and engine compartment) is stinky too, i have been thinking about routing an air hose from the drivers side gusset into the fan inlet to pipe fresh air only. now it sounds like i just need to run the breather hoses from the heads to a fitting on the carb tops(?)
honestly i'm just too stoopid to understand the whole crank case vent issue anyway, but that's ok.

here's an interesting site i ran across discussing this issue as it relates to a triumph:
check out the rollover pics...

The T3 and T4 are very similar engine arrangements so here's my carb'd T3 engine and how I have the breather set up:


The long silver box is an after-market breather (CB Performance) but it is on the stock location. The two black hoses on the sides that disappear towards the front of the engine (top of the picture) go to the valve covers. The excess case pressure is vented to the top of the right carb. I used common, brass barbed fittings from the local Ace hardware store.

As a side note, I no longer have the valve covers vented, I just have the one line going to the carb top. So far, after a summer of hard use, I've experienced no issues whatsoever and valve adjustments are a bit easier (no hose to deal with when removing the valve cover). This is a test against convention after-market designs to see how it affects oil leaks due to case pressure. The idea comes from a certified VW mechanic (old school) whose drag race team didn't use vented valve covers. I've known him long enough to trust him and so far he hasn't steered anybody wrong (Russ Wolfe, GREAT guy!). Just a thought, you might try it?

Get a Haynes shop manual and look at how the stock car did it. I know that later on they had the vented covers but, according to the diagram, air went IN to the cover (not OUT) for better emissions quality. Over-pressure was then vented into the air cleaner. One day I'll tap in a vacuum/pressure gauge and see exactly how it works...

The key is removing the breather box from the area where the fan inducts it's air. In my old teener I put mine in the rear trunk and never had an issue with the smell.the breather boxes that we make/sell allow the box to be mounted in the engine bay but vented into the trunk or the atmosphere. The small boxes made for VWs are nominal at best because once they are filled to capacity they are virtually worthless. Volume is king.

From what I read on the old shoptalk forums, a setup like this would be a closed system, vented to the carbs, with no oil fumes. One line would be capped, for the type 4 application.

thanks, jake. i'd rather keep my trunk from getting stinky though.

Thomasgotten, that's a great diagram, and makes sense. maybe that'll resolve it.

pfb