[T3] First Steps Engine Reassembly

[Jim Adney]

On 6 Jul 2018 at 1:20, Dave Hall wrote:

>  The 36HP just put any oil mist down onto the road through a slit rubber
> cap, rather than taking it into the aircleaner as on later Type 3s.I think
> there's a tube alongside the dynamo stand - which is part of the crankcase,
> as you say.

The goal of the breather system is to let blowby gases out while keeping oil 
in. It's evident that achieving this goal was a challenge since VW made so 
many changes along the way.

Type 3s had the same tube and slit rubber cap up thru '66 or 67. In fact, I 
think ALL cars had a similar tube until it was outlawed, at least in the US. It's 
called a Draft Tube and that was how the engine got rid of the blowby that 
got past the piston rings and into the crankcase. The hope was that the oil 
mist could be captured and returned to the crankcase. That was the function 
of various things VW put along that path.

One of my Beetle shop manuals shows a contraption that VW suggested to 
help separate the mist from the blowby. It's quite complicated, consisting of a 
formed plate, a tube, and a cap, all presumably brazed together. It installed 
between the case and breater stand and stuck up into the breather. I'm 
amazed that VW suggested that it be locally made, to prevent excess oil loss 
due to oil mist loss. No shop would have the facilities to make something like 
that one at a time.

Up thru '69 or '70 there was a sort of knitted plastic ball that looked like a 
blue nylon kitchen scrubber that sat in the breather box. It was there in the 
hope that tiny oil droplets that were entrained with the blowby would stick to 
the plastic filaments and coalese into larger drops which would eventually 
drip back down into the engine. It worked, but it also collected water droplets 
and froze up in very cold weather. Almost all of those were removed and  
thrown away at some point.

Type 3s got the larger square breather box around '68. The purpose of that 
was to allow the blowby to slow down and give the oil mist time to settle out 
and drain back into the crankcase. By '68 the draft tube and slit rubber cap 
were gone and replaced by a very similar drain tube that returned liquid to 
the filler pipe and sent blowby gasses to the air cleaner.

There are a number of things that appear to be wrong in the parts book. The 
lovered plate is called out starting about Jan 1, 1969, but I'm sure my '68 
came with it. The early teardrop breather box doesn't show up at all, but the 
slit cap does. I guess that means the square box superceeded the  
teardrop one so I can't confirm when the square box was introduced.

The parts book also shows the slit cap up thru '71, which I KNOW isn't true, 
since my '68 didn't have it. I don't think ANY FI engines ever had it. I think 
the last year for the slit cap was '67 or '66. Anyone out there know which?

And we were wrong about the gasket under the breather stand. Both the 
Bentley and the parts book call out just 1 gasket, and, oddly, they place it on 
the underside of the louvered plate. My guess is that one gasket was used 
when there was no louvered plate, but I think no gasket was used once the 
louvered plate was introduced. Otherwise, why ripple the edge of that plate if 
you're going to put a paper gasket there?

Sorry for the long response....

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