[T3] Oil bath filter

[Jim Adney]

On 15 Jul 2013 at 14:13, Daniel K. Du Vall wrote:

> I think I got some views of one.
> http://cal-look.no/lounge/index.php?topic=12030.30
> I was curious about the dipstick tube mostly.  

I scrolled down thru there and found one side view of the breather 
system I've been talking about. His installation is skewed, however, 
because it appears he's using a universal case and had to avoid the 
Type 1 dipstick tube that he capped. The tube from the Type 3 
Breather box should line up with the tube coming up from the Type 3 
dipstick, so that there would be no dogleg, and no stress, on the 
connecting hose.

I tried to find some photos in the Bentley, but came up empty.

In this '68-71 system, oil mist is separated from blowby gasses, and 
the oil is recovered and drains back down into the engine via the 
dipstick tube. Gases get routed to the air cleaner intake, where any 
remaining oil mist will be picked up. Nothing bypasses the throttle 
plate, so there's no effect on idle.

The other advantage of this system, over the later one, is that 
there's a small vacuum (via a large bore) drawing on the breather, 
but this vacuum INCREASES as engine load and airflow increases. On 
the later system, the vacuum DECREASES as the airflow increases.

The later system seems to work just fine with the stock engine, but I 
suspect that it's a very close thing, and deviations from stock could 
put it out of it's acceptable operating range.

If you convert to the earlier system you'll need to plug the vent 
holes in the rocker boxes, as Bob mentioned.

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