Date:         Wed, 23 Aug 2023 08:59:23 -0700
Reply-To:     Alistair Bell <ragnarhairybreeks@ICLOUD.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Alistair Bell <ragnarhairybreeks@ICLOUD.COM>
Subject:      2.1 wbx oil tower, vent, function
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Recent thread about it made me want to try to understand it better. I think I’ve got it more or less right, but please correct me if not.

My understanding of the oil tower, crankcase ventilation, on the 2.1 wbx

The main body of the tower has a removable baffle . Above that you can see a right angled bent tube. This tube has a small hole in it facing down, towards the engine. This tube continues out thru the tower and is what connects to the engine air intake upstream of the throttle body via rubber hose. Also in that path is a heating element , with a narrow orifice, maybe  5mm diameter. Heating element to prevent icing , the narrow orifice presumably to restrict air flow to a degree.

Back at the tower, inside, where the tube curves 90 degrees up ( and again, mention of the small  hole on the underside of that bend) the tube ends and there is a rather weak spring supporting a rubber diaphragm. The spring keeps the diaphragm off the end of that tube. In other words, the passage from the crankcase to the intake boot is clear. The diaphragm is attached to the tower top, with some space above it. There is a small hole on the underside of the top of the tower that connects to the space above the diaphragm, thus keeping that space at atmospheric pressure.

So when does that diaphragm do anything? Well… as far as I can tell the diaphragm is pulled down to block the bent tube leading out of the tower when you have greater than a certain amount of intake vacuum. Probably not at idle or at wide open throttle . More likely at some mid throttle range.

Btw, the pro training manual has description of the tower and function but I’m not sure about the statements made there of when there is high or low intake manifold vacuum. 

That little hole at the bend of the tube inside.. I’m guess that allows some passage from crankcase even when diaphragm pulled down under high intake vacuum.

In short, my understanding is… the crankcase vapours are allowed to travel up thru the tower and then into the intake manifold when there is not sufficient intake manifold vacuum to overcome the spring pressure and pull the diaphragm down.  When there is sufficient vacuum then the diaphragm is pulled down and the passage is closed saved for the little bleed hole .

Ab