[T3] cylinder head breather ports on a 1972 Squareback

[Jim Adney]

On 3 Aug 2013 at 20:00, Dave Pallo wrote:

> [[[I think you'll be okay if you plug the extra holes in the air cleaner and
> just run it this way. With the original setup, this would draw clean air
> into the heads and flush out the case, keeping condensation to a minimum.
> This would be especially useful in cold weather.]]]
>  
> I don't understand this, Jim. If his pcv is drawing air out of the
> crankcase, the air has to be replaced, right?

Without fresh air getting into the case, there will be a bit of a 
vacuum in his case, much of which will be alleviated by blowby and 
vapor from any gas in the oil. This should not cause any problems.

> When I first got my '72 up and running, I too did not have the ports in the
> heads and I installed brake line sized ports in the valve covers to allow
> air in. I was flinging oil out the fan end of the motor at the time, and
> this list told me I needed larger air ports to let more air into the case. I
> didn't understand why, but I then installed about .500 diameter ports into
> the valve covers and my flinging oil problem was solved.

The situation you describe occurs when you don't have the breather 
ports in the heads AND you don't have the IAD suction applied to the 
breather. In this situation, you will get pressure buildup in the 
case from accumulated blowby. A pressurized case will cause oil to 
get blown out of the unsealed rear crank hole.

I'm assuming that he has the intake portion of his '72 system intact. 
If I'm wrong about that, then this changes everything.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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