Crankcase vent pipe - where should it go?

1961-1968: a.k.a "Finnie" or "Heckflosse" models
190, 190D, 200, 200D, 220b, 220Sb, 220SEb, 230, 230S, 250SE coupe, 280SE coupe, 280SE 3.5 coupe, 220SEb cabrio., 250SE conv., 280SE cabrio., 280SE 3.5 Cabrio., 300SE, 300SE coupe, 300SE conv., 300SEL
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thebassetthound
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Crankcase vent pipe - where should it go?

Post by thebassetthound » Wed 25 Jul, 2018 5:51 pm

Per the attached, the correct location is for it to feed back via the air filter.

On my 230S someone has sealed the inlet on the air filter housing, and added a makeshift bit of heater pipe and routed it to vent out the chassis under the engine.

So which is right?

And should I leave mine as it is, or put it back to the way Stuttgart wanted it originally?

TYIA!
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Last edited by thebassetthound on Wed 25 Jul, 2018 9:29 pm, edited 1 time in total.
1966 W111 230S - on club plates (ongoing restoration)
-
1972 Volkswagen Type 1 - dak dak dak dak

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Chai
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Re: Crackcase vent pipe - where should it go?

Post by Chai » Wed 25 Jul, 2018 7:39 pm

When I was a teenager, my dad (or his mechanic) did exactly the same thing on the not-yet-old (non-MB) family car. I could not change his mind that it was not a good idea then.

The positive-crankcase-ventilation evacuates the blow-by gas that escapes past the piston rings and oil vapour. The vacuum inside the air filter at the location of the intake hose sucks up these gases. The mixture is then burnt up.

End result - less pollution.
Chai
1974 450SLC

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John Green
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Re: Crackcase vent pipe - where should it go?

Post by John Green » Thu 26 Jul, 2018 5:52 pm

Chai wrote:
Wed 25 Jul, 2018 7:39 pm
When I was a teenager, my dad (or his mechanic) did exactly the same thing on the not-yet-old (non-MB) family car. I could not change his mind that it was not a good idea then.

The positive-crankcase-ventilation evacuates the blow-by gas that escapes past the piston rings and oil vapour. The vacuum inside the air filter at the location of the intake hose sucks up these gases. The mixture is then burnt up.

End result - less pollution.
The main reason this mod is done these days is that the engine is worn out and the crankcase has too much blow by pressure. This results in not only fumes, but oil being deposited onto the tops of the carburetors. I would check this, before reconnecting it.
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John Green
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Re: Crackcase vent pipe - where should it go?

Post by John Green » Thu 26 Jul, 2018 5:52 pm

Chai wrote:
Wed 25 Jul, 2018 7:39 pm
When I was a teenager, my dad (or his mechanic) did exactly the same thing on the not-yet-old (non-MB) family car. I could not change his mind that it was not a good idea then.

The positive-crankcase-ventilation evacuates the blow-by gas that escapes past the piston rings and oil vapour. The vacuum inside the air filter at the location of the intake hose sucks up these gases. The mixture is then burnt up.

End result - less pollution.
The main reason this mod is done these days is that the engine is worn out and the crankcase has too much blow by pressure. This results in not only fumes, but oil being deposited onto the tops of the carburetors. I would check this, before reconnecting it.
Inaugural OZBENZ national meet this September, all welcome to attend. https://ozbenz.net/viewtopic.php?f=46&t=25165

M.B Spares & Service 14-16 Lyell St, Fyshwick ACT. Ph 02 6239 1099

http://mbspares.com.au - Supporting Australia's Mercedes-Benz Enthusiasts.

thebassetthound
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Posts: 12
Joined: Wed 05 Jul, 2017 10:17 am
Model you own: w111
Location: Melbourne Victoria

Re: Crankcase vent pipe - where should it go?

Post by thebassetthound » Fri 27 Jul, 2018 2:07 pm

Thanks guys - exactly the feedback I was after!
1966 W111 230S - on club plates (ongoing restoration)
-
1972 Volkswagen Type 1 - dak dak dak dak

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