Correct way to vent the crank case

[oprn]

Why?
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Our cars get old, we get old but driving an old VW never gets old!

[Glenn]

^^^^^^^^^
I don't get it.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
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[raygreenwood]

Kind of asking the same question. So let me walk through this:

1. You have what was the original road draft tube connected to a hose. Yes?

2. That hose goes to what looks like a fuel filter canister, right? (Probably with stainless steel media inside?)

3. I am assuming that the fuel filter canister is open at the other end so in effect it's still kind of a road draft tube

In the original stock form with the pinched nipple on the end, the road draft tube should really never be drawing inward.....so I am not sure what the filter is doing for you. Unless, do you have another source of vacuum drawing on the case?

Ray

[oprn]

I just don’t see the point of filtering the oil that drips out.
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Our cars get old, we get old but driving an old VW never gets old!

[chrisflstf]

I don't think the filter is to filter oil that drips out, I think the intent is to keep any dirt from being sucked back in (even if it can't or doesn't)

[bedlamite]

When you stop the engine, it cools down and the air inside contracts and pulls a little in a filter makes sure it's only air.

[oprn]

Sorry! There is just no way on God's green earth that an engine cooling normally is going to suck with enough velocity to draw a piece of cottonwood fluff up that draught pipe never mind dirt!. You are worried about something that will never happen... unless you are in the habit of running your cars full bore into a lake!

Don't believe me though, next time you shut it off see if you can get it to suck a tiny bit of tissue up the hose... Take your time...
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Our cars get old, we get old but driving an old VW never gets old!

[Zed999]

I built a 2L type-1 before I knew quite enough about not over oiling the barrels and rings and running the rings in. It chuffed like a steam train through the breather which was vented straight to the road and revved to 6,500 rpm but it didn't leak oil.
The earlier fillers with vent down tube had smaller "to filter" take-offs. That's what I used but it still didn't leak.

I tell a lie - it leaked with a BMD Serp pulley before I replaced the oil spiral with one wire cut from an OG pulley, then also didn't leak later when I replaced the serp system with stock.

I'm not keen on Ali pulleys, the original steel spiral is quite a complex design if you put your glasses on.

[jim martin]

Read this first ,
http://www.vw-resource.com/crankcase_ventilation.html

Best to start with understanding how the original system was designed And how it operated.
Then you can start to understand when you remove the carb draw , remove the original grooved pulley or install a sandseal and vented valve covers where all the issues start coming from.
- race motor or street motor . Crankcase does not care what cam and heads you use . It’s still say a 82mm crank whipping around in there maybe another 1000-1500 rpm more and RINGS need to seal , Period .
And also don’t forget to make things simple if your engine displacement is say 2275 cc it’s also displacing the same volume in the case .
- so most larger displacements dual carb motors have removed the draw from the carbs and removed the stk pulley and installed a sand seal .now you understand the need to allow a greater movement of air in and out of the case as well as acct for some blow by . So vent the hell out of the case with the largest id hose you can get on the stand ,and you guys like adding a vent to the fuel pump block off , go ahead throw that on there 2.



http://www.vw-resource.com/crankcase_ventilation.html
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[Schepp]

I modified the stock oil filler. Cut the original vent pipe off, then drilled the hole to the same I.D. as a -10AN. A new appropriate sized extension tube and SS -10an bung was welded on.
Note the down tube and rubber piece at the end still exist.