Increased the vacuum??

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1981 240D 4sp manual. Ivory White.

The turbo sucks the vapors out of the valve cover via negative pressure or vacuum.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

Ditto on what everyone is saying. Pipe flow resistance is dealt with by increasing pipe diameter. I’ve been out of school too long...the flow is either proportional to the diameter or the square of the diameter. Basically you want a big diameter pipe. Bigger the better. Maybe more extreme if the flow is turbulent...again I cannot remember.

The pressure drop is also proportional to the length of the pipe. Like breathing through a garden hose as a kid underwater...tried that once. Long tubes = lower flow.

The right angle back pressure happens because of friction and inertia. You’re radically changing the direction of the flow with a right angle.

Shern - your first separator has a sintered filter in it. Depending on its porosity it’s going to create more or less restriction to the flow. The second has tiny nipples. Those don’t look good at all.

One thing I got right on my salsa jar design was big diameter tubes (same as OE breather) and no baffling. I just used a credit card to separate input and output and stuffed the bottle with Brillo. My flaw is that the tubes are long. It was hard finding a convenient place to hang the bottle.

The really fancy industrial condensers from Parker Hannifin use Brillo and giant volumes. I think they try to cool the can to encourage condensation.

This is really a bandaid on both of my cars. I may be wrong but I think I’m due for some valve stem seals on both. It has been discussed here that the turbos have more exhaust back pressure that will come back through the exhaust valve guides on tired engines. Even though the stem seals aren’t supposed to hold back blowby I suspect having fresh ones can only reduce gases that slip by the exhaust valve guides. Next valve adjustment I’ll swap mine. I have them sitting on my shelf staring at me.

Yeah that blow by meter was an education. the oil separators and drains were our competitive edge. Most of the other players in the market would have their sensor fill up with oil after a week on the dyno.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles

Good point. I didn’t think of that.

Still I think it’s a good idea to keep the separator’s flow restriction down. There’s a point where the restriction can get so high it doesn’t matter how much you pull vacuum...depends on how well the separator is designed. Some have really small nipples. That’s why I picked the BMW n54 style.

This one:
https://www.amazon.com/NovelBee-Polished-Aluminum-Engine-Reservoir/dp/B088CT74CD/ref=sr_1_8?crid=HTKA5TUU9HSJ&dchild=1&keywords=bmw+n54+oil+catch+can&qid=1619107807&sprefix=BMW+n54+oil%2Caps%2C229&sr=8-8

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles

Yes it is important not to restrict flow doing so increases crank case pressure and you will notice leaks.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

This is a fantastic explanation –thank you.


Understood, thank you. As I'm running an NA engine, I assume I am only experiencing positive pressure from the crankcase?

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1981 240D 4sp manual. Ivory White.

3/4" nipples on this one. I think that's even more than the stock breather... Interesting.

Some of these come with breathers, which seems like a good idea for increased airflow, though I can't understand how that wouldn't muck up your engine bay over time.

e.g.: This guy

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1981 240D 4sp manual. Ivory White.

And here's another interesting option...

This one has 25mm nipple/inlets. It seems to be a knockoff of another catch can called the Mann Pro-vent 200, which seemed to have been installed in a few of our cars. I found a few cryptic references to it in the archives.

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1981 240D 4sp manual. Ivory White.

That looks similar to the unit I took from a blown tier 4 final Kubota diesel. Mine has a filter and screen media in it.

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Satan creates nothing: he only ruins everything. He does not invent: he tampers. And his followers are no different ~ Archbishop Carlo Maria Viganò

Not sure about you turbo chaps, but the breather hose on my 616 has an internal diameter of about 12.35mm (about half an inch). The outer diameter came in at about 15.24mm.

That should expand our options.

One possible issue with the “Mann provent” is that it appears to require a line to the sump.
Mounting another catch-can in lieu of the sump I think is just a little too ridiculous even for me.

Ykobayashi- given your physics tutorial, longer lines->more air to displace ->more back pressure. I’m considering drilling two screw holes into the air cleaner housing and mounting it right there.

Any flaws in my logic?



.

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1981 240D 4sp manual. Ivory White.

The images all show significantly smaller hose I.D. and that's simply never going to work well .

The factory breather hose is 12MM I.D. and all the Amazon ones are speced to be 10MM, not going to work .

Shern, you and I really need to meet so you can eyeball my old battered '82 240D and see real world oil weeps and seeps on an engine that's run hard daily .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Pretty brilliant actually. This is what the Mb engineers did on my W126. They put the separator in the air cleaner. On my 240d the separator was positioned at the front of the engine between the valve cover and intake. It was positioned well.

I wouldn’t worry about rigging a sump. Hmmm, I think my 240d had one. Yeah, foggy but I recall putting a cork in it when I removed the entire contraption. If you don’t have the plumbing just empty periodically. That’s why I do on my current cars.

Odd...I recall now mine bolted on to two nice m6 bosses on my intake manifold right at the #1 runner. You don’t have this mount? Mine self destructed and leaked hence I removed it. Edit - no my memory is foggy...maybe there was a bracket around the thermostat housing. I recall there was a mount.

Here’s what mine looked like before the delete.
https://www.benzworld.org/attachments/img_5456-jpg.2664308/

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles

You're right about that. I measured the hose in the post right above you but the last two catch cans are 3/4" input/output so they'll be fine.

I'd love to compare to 240s! You let me know where and I'll be there.
I'll show you what an obsessively degreased, non-leaky 616 looks like.
I too run mine hard daily but I also sweat the details I probably shouldn't.

I don't have this mount or manifold... It's close, but the breather tube hole on my manifold is on the engine side of the air-cleaner.

Seems like good practice putting some steel wool in these things? I can't say I totally understand the varying baffle systems, but I do understand giving hot vapors a place to condense.

Are there any issues with gas temperatures/hose materials?

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1981 240D 4sp manual. Ivory White.

I use stainless steel pot scrubby from Walmart. I think it’s 3M brand. It is basically a continuous chip so it only has two ends. I think this is important because I don’t want that stuff breaking off and going into the intake. Super durable stuff made to be scrunched up and manhandled.

I notice some people use the copper stuff too. It seems to help coalesce the oil without having a lot of flow restriction.

Don’t use steel wool. Spring for the $2 pot scrubby.

I use this. https://www.walmart.com/ip/Scotch-Brite-Stainless-Steel-Scrubbing-Pads-3-Pack/13281617

I think I used 2. I kind of stretch them out to fluff them up so to speak.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles

WOW! .

I wish my 20D looked like that ! .

I try hard but dang man .

Shern, zip me an E-Mail and we'll get together and compare 240's .

Mine isn't much these days but God knows, I love it to death .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better