Retro-fitting an oil catch can/separator
 

My 240 (81) didn't come with one.

The crank case vents directly to the intake manifold.
I'd like to capture any transiting oil thus preventing it from being burned.

Have any of you retro-fitted a separator? Either stock from another year or aftermarket?


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I made my own, but I would rather buy a known good brand of one if I did it over (which I might since I'd like to try adding a second vent that a few people have had success with). As long as it's well designed it doesn't matter. I bought a kit from someone advertising on here and it was little better than a straight piece of hose. With these engines they'll need some kind of baffling at least, if not a packing material like bronze wool.

I'm sure I'll be in the minority here, but if the EGR is disabled (as it should be on these engines), what's the harm in letting the engine consume it's own oil vapor? It'll never build up in the intake manifold or create the tar-like deposits that the EGR soot creates. The oil vapor deposits in the intake manifold cause no harm to anything in the intake system or the engine, adding a catch can is just something else you have to maintain.

For me literally the only reason was eliminating one cause of runaway potential, even if it's rare. Also I don't have the stock air filter anymore so I had to do something different anyway. Was not under the impression that it would add 50 HP or anything like that, to be sure.

Some of it goes through the air filter. In the early versions of the Jeep 4.0L, this is know as blow-by. Its not really blow-by, though.

I removed the leaking OEM can from my 82 240d. I ran a straight pipe to the intake. I got a lot of sludge in there after driving five years. It didn’t seem to hurt anything.

On my 300d (an 85 with no integrated separator - blowby goes straight to the turbo) I added a kit marketed to the bmw n54 guys. The hose diameters worked well. The images are buried somewhere in my Got a 300d thread. I put this in because I was getting a little smoking at intersections when I stopped after a hard run. It has reduced the smoking.

On my 300sd I wanted to do the same thing. I had been struggling with a cylinder with low compression. The engine had a shaking idle but made smooth power over 1000 rpm. I did a leakdown and suspected ring blowby. So I did a ring soak using Berrymans and that really helped the idle. Suspecting stuck rings I did a bunch of other things like switched to synthetic oil with some Marvel oil added to it. That smoothed it out.

So at that point I theorized that maybe just maybe I’m putting more oil down the intake than I can get rid of down the exhaust. I remember from my gasser tuning days, the best way to decarbonize an engine was to just run it with a slightly lean air fuel ratio. So any oil I can prevent from leaking down my intake is oil I won’t have to burn off. And my SD had a decent amount of oil pooling up in the u-tube. So that was my reasoning. Rate in minus rate out is rate of buildup.

Not sure if it worked because I did a ton of other things to the car to stop the shaking. But it doesn’t shake anymore. It has gradually improved so I figure it’s the new oils or the separator. The ring soak made an initial improvement. I may sound crazy but the MMO + synthetic may have actually helped...that is my feeling at least. (Thanks for the tips Rogviler).

Ok that’s a long story. So I made mine out of an old salsa jar with some stainless steel Brillo pads. I 3d printed the hose nipples. Basically free. Let’s see if I can find the images. Oh yeah the top is 3d printed and the nipples are electrical conduit I had leftover from a project. This was an experiment in cheapness.

I know some of you guys don’t believe in this stuff. Maybe it brings some extra complications like flow restriction on the vent which may cause oil leaks on the engine. But I figured I try it awhile and my cars are running better.

https://live.staticflickr.com/65535/...d1747b446a.jpg

This is exactly where I landed and why I wanted to try this.

I am aware of theoretical flow restrictions -you've not suffered any ill-effect?
I've actually downloaded some of the Cad files you've uploaded over the years.
One off printing on these DIY printing sites is still stupidly expensive... I'll eventually get a maker, but until then, I'm probably looking at third party.

How much oil are you finding, every, let's say, 3000 miles?

PS -do you have a photo of that can, installed?

Shern,

Different designs have different amounts of flow restriction. I just have a single plate separating the intake and output. Kind of a vane made out of an old credit card and glued to the lid. The N54 bmw one has a little grill inside and it has more restriction. I’ve not blown out my seals though. My engines are leak free.

I made some flow meters for pcv blowby early in my career. They had vane type oil separators. Just fling the vapor against some walls and make it turn a few corners. Collect any condensate dripping down the walls. Once I removed the obvious restrictions (small holes) the pressure drops mostly came from long runs of hose and the right angle turns. The Brillo pad is pretty low restriction. I tested the design by blowing through it.

I’m so proud of my flow meters. Got to show them off here. :) I made them first thing out of engineering school. OMG they still make it twenty years later. You can check out the oil separators on each end.

http://www.labcell.com/media/20886/blow-bybrochure%20e.pdf

So, what I was saying is long runs of tubing and right angle turns create a significant amount of back pressure once the obvious restrictions are minimized.

I didn’t put the 3d files up on thingiverse. They actually sucked because the conduits didn’t fit well and required a lot of JB weld for sealing. Also 3d printing sucks for holding pressure. There are microscopic pinholes in my solid caused by the process and it slowly develops a film of oil all over it and weeps. Bottom line I wouldn’t recommend printing my design out without major redesign.

Random thoughts on 3d printing. My printer was really cheap. $199 shipped. Easy to set up and use - watched three hours of YouTube vids. Don’t pay for prints just buy a cheap printer from Creality. Then there is always a big library nearby that often lets you bring in things to print for a tiny fee as long as it doesn’t turn into a weapon.

If I had to make this thing again I’d just buy two plastic elbow barbs from home depot and glue them in with bath silicone or JB weld right down to the lid.

The jar was nice because I can see the oil use. It was also free. I consume a lot of salsa. To mount it I got a magnetic coffee cup holder from a junk yard. I just stuck it to the car.

I haven’t run them 3000 mi. I’d say I collected a quarter cup of oil in 1000 miles.

The SD

https://live.staticflickr.com/65535/...5660ea0291.jpg

The blue 1985 300d

https://live.staticflickr.com/65535/...98babb3751.jpg

https://smile.amazon.com/gp/product/B07KK61723/ref=ox_sc_saved_title_3?smid=AKH7Q6S5LSBBS&psc=1

I've had this one in my Amazon cart for awhile. Next step in slowing down the rate at which the truck marks it's spot in the shop. I'll be watching this thread with interest.

Your blow by meter is fantastic. Boy would that have stemmed a few stale arguments around here some years back...

I'll eventually get around to buying a printer, though I'm kind of waiting for the next gen.

What you're saying re: right angles is interesting. Would that make this unit:

https://www.amazon.com/Engine-Separator-Catch-Reservoir-Baffled/dp/B078H6C2Q5/ref=cm_cr_arp_d_product_top?ie=UTF8

less efficient than the unit posted below?


Had eyes on this one this morning...

I forget the rule of physics that governs flow speed as a function of bandwidth -so I may be off the mark here- but I was hoping to find a catch can with 1/2" barbs to approximate the OEM breather dimensions.

Here's one that even has a dipstick and breather!

https://www.amazon.com/Ruien-Universal-Breather-Aluminum-Separator-Reservoir/dp/B06XKCSHSL/ref=sr_1_14?dchild=1&keywords=oil+catch+can&qid=1619044410&s=automotive&sr=1-14

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Oil Catch Cans
 

Interesting .

Using less than the stock size hose in any of these isn't going to work well in the long run .

Equation of continuity is what I was thinking of... I think that only relates to fluid dynamics though.

Do you know this for sure or is this an intuition?
In what sense will it “not work well?”

I used the same diameter hose and fittings as stock and have definitely had more seepage around fittings and the oil cap, likely from the slight increase in resistance from the baffles and packing. Hence why I wanted to try doubling up the vent lines. Others have reported the cessation of leaks after doing that.

That's good info. I wouldn't have guessed size would be a huge problem, but now that I know, I'll look at other options and prioritize something with decent flow.

I had experienced the exact same with a smaller diameter hose. Increasing the hose diameter increased the vacuum and reduced the crankcase pressures. No more leaks.

Increased the vacuum??

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

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.

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

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

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?

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

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.

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.

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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Hose I.D.
 

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 .

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/

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?

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.

Oil Separator Picture
 

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 :heart: .

Ah, yes, I did mean steel scrubby! I have a bunch under the sink.

So it turns out that most of the amazon catch cans have in/out ports that are M16x1.5.
Finding nozzles with barb fittings with IDs >12mm shouldn't be too difficult.

Might have to step up or down a few times getting hoses to match, but this all feels eminently achievable.

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I picked up a provent 200 knockoff on amazon.
It's definitely overkill, but I paid about $15 as a warehouse deal.

I'm thinking of mounting it directly to the air filter assembly, in the triangle region between the assembly, the valve cover and the A/C line. The thing I'm concerned about is the heat coming off of the exhaust manifold.
The provent is some sort of plastic.

http://www.peachparts.com/shopforum/...1-img-8390.jpg

There's no turbo below so I imagine it's considerably less heat than say a 617a. Any ideas what temperatures I might expect in that area under full load? Need I be concerned?

Another thing. The provent has 1" ID inlet/outlet nipples. I need to find a way to step down to something like 1/2" to match the stock breather pipe going into both the valve cover and the manifold. I assume I should be using brass barb reducers, but that's based on my assumption that the blowby gasses are hot and oil might erode plastic. On that note... should I be using fuel hose for this application or is oil heater hose or other, okay?

clean 240d
 

Oil leaks: The dude does not abide.

Shern's 240D
 

What year model is your 240D ? .

My '82 has a oil mist separator I I don't see on your underhood picture .

Maybe that's why you're needing a catch can but I doubt it .

Early morning Nate?
The one in my signature -1981

And that is exactly why I need one.
They only shipped on 82 and 83 models. Hence the retro-fit part of the post title.

More like late night ~ I was reading nearly 'till dawn .

Yeah I didn’t quite get that a few posts back. My 82 240d had the separator bolted to some bosses on the intake. It also had a drain to the sump.

Mine got cracked and leaked. The bosses were a convenient mount point for other accessories.

All done.

https://i.ibb.co/k8Tncs3/IMG-8425.jpg

https://i.ibb.co/Lpq5sKV/IMG-8426.jpg

https://i.ibb.co/PwZQxrp/IMG-8427.jpg

https://i.ibb.co/N9ZwCs4/IMG-8430.jpg



In the end, it was a pretty light unit and didn't require too much in the way of mounting.
I took the opportunity to degrease my intake manifold, replace the original gasket (shredded) and replace the breather elbow.

https://i.ibb.co/bR3Lbw1/IMG-8414.jpg
https://i.ibb.co/qm14JHC/04-A54-A7-D...256-D1-EF1.jpg

Guess we'll see how it goes over the next few months, but I suspect it will be doing its job. Will keep this thread updated with observations.

Nice work Shern. Very clean looking installation.

That reducer is an useful looking part. Where do you get those?

Thank you kindly.

Those reducers are actually dishwasher connectors I bought at homedepot.

I bought 1/2" ID fuel hose that fit just about snugly into the 1" ID inlet/outlet ports on the canister. I was able to twist the fuel hose into the narrow end of the connector and then about a 1/2" past the wide end and then into the plastic port of the canister.
Not sure what kind of rubber the dishwasher connectors are made from, but the the way I'm using them, they're likely not seeing any vapor at all.

On the valve cover/manifold end, I found an extra breather pipe at the JY and hacksawed 2" inch sections to use as joiners. Shoved them in there pretty good, they're mostly invisible.


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Oil Catch Canister
 

Well done Shern ! .

I guessing you'll drain the clear plastic hose every oil change ? .

Exactly. Routed the drain valve near the sump plug for that very reason :)

Hah! Filed away mentally for future reference. Thanks!

Rubber Elbows
 

I hope they'll last but Diesel contaminated oil tears or anything rubber quickly .

I don’t think there’s any contact. If there is, I’m sure I’ll get a couple of years out of them and they’re only two bucks each to replace.

My OM617 has a few oil leaks and I'm thinking that it is exacerbated by blowby. I'm wondering what people think about creating a second vent in the valve cover and venting to a catch can then on to the intake. I would keep this in addition to the stock vent inside the air filter.

That’s an interesting thought. The valve cover has some internal baffling inside. I’m not sure what’s under the glued in plate running a long the top. I guess it’s supposed to stop splashing.

I think my car is getting a lot of oil from worn valve guides combined with old valve stem seals. I bet it works like a really good atomizer in there during the exhaust stroke when the exhaust valve is open and the turbo is putting a bit of back pressure on the exhaust. I have some seals on the shelf to do the job. Just waiting for the valve adjustment interval.

It can only help. I’d probably look at all possible remedies before cutting a hole in my valve cover.

My separator has been working well on both my cars. I collect a tablespoon full of oil every two months with light use (300 miles a month). I figure it’s better in the cup than on my rings.

On my 300SD there is a stock cyclonic separator that I use in series with the BMW N54 style separator. The drawback of this is more backpressure. Two crank case vents would definitely drop the pressure but I haven’t had any issues yet. My engine remains well sealed.

ETA - on both of my cars I had leaking seals. Yes, it has to do with crank case pressure but it also had much to do with 40 yo hardened gaskets. I had leaking turbo drain seals/gasket, oil Pan, oil drain plug, vacuum pump gasket, valve cover gasket, breather drain seal, U tube gasket, crank case vent elbows, injector pump gasket, oil filter block gasket, main seal, oil cap gasket and more weeping. Replacing these stopped the oil leaks. Theyve withstood the addition of the extra separator can so I must admit the leaks had as much to do with old rubber as they did blow by.

I mentioned this offhandedly on page 1 but didn't elaborate. I have seen good evidence that a second vent line will help with oil leaks since it's relieving even more pressure. I plan to do this at some point myself.

I think I'm going to do it in the next few weeks. I'll let you know.