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RE: [T3] Aux air regulator?

On 21 Jan 2005 at 22:10, Dave Pallo wrote:

> [From '68 to 71 these vapors were sucked thru a hose to the air cleaner 
> where they were drawn into the engine and burned.]
> so in these engines, if crankcase air and vapors were drawn into the air 
> cleaner via a hose......
> where did the crankcase get air to replace what was drawn into the air 
> cleaner?

The the volume of air that exits is only that which leaked past the rings. 
There is little or no suction on the case, so this is just a vent to prevent 
pressure buildup inside the case.

> [For 72-3 the vapors were pulled directly into the intake manifold. Extra
> breather ports were added to the rocker boxes on top of the heads where
> additional air, cleaned by the air cleaner, could be pulled INTO the case 
> where
> they would scavenge vapors on the way to the breather box and the intake
> manifold. These engines are easily identified by the fact that they have 2
> plastic caps on top of the breather box.
> The latest system is the only one which could accurately be called a 
> positive crankcase ventilation system.]
> now this system I understand.....suck vapors into intake, replace with 
> clean air from air filter into cyl. heads...makes sense.

Yes, this is the only version which actually passes fresh air thru the engine.

> It appears I have a '72 breather box (with it's 2 plastic caps and a
> hose nipple on the underside of the box) which now has a hose going to
> the intake. however, I do not have heads on this engine that have
> breather ports to let in fresh air............. so, how do I hook this
> baby up?...I'm afraid if I suck air into the intake with no means of
> replenishing the crankcase with fresh air......can you say vacuum?? 

The only real danger is that you might suck in some dirt around the fan hub at 
the rear of the engine. There is no crank seal there. For most cars this is not 
likely to be a problem. For cars run as dune or swamp buggies this could be a 
significant source of dirt in the engine. 

> do I put a hose from the bottom of the breather box to the air cleaner so 
> it can draw vapors in like a '71 engine? will this work?

You would have to remove the nipple assy. first and gut it. There's a valve 
there which requires some vacuum to pull air thru. Simply connecting that valve 
to the air cleaner will let pressure build up in the case and result in oil 
blowing out around the fan hub.

You can do nothing, and it will probably be fine.

You can keep your eyes open for a good pair of 72-3 type 3 heads with the 
breather pipes, or some new heads have the bosses there, so holes can be 
drilled and tubes pressed in just like the OE heads.

Or you can find a 68-71 breather box and oil filler pipe (and the hose that 
connects them) and install those. You need all 3 to make it work right. This is 
often the most useful and straightforward solution.

> (of course I would have to close off the line to the intake as well)


Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

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