MyE28.com

I'm tired of the constant influx of oil into my air box, I thought about just buying a hose that goes out from the oil separator and route it to the ground, but then I'd have oil stains in my garage and lose the vacuum that probably makes this thing work efficiently.

Has anyone installed an oil catch can? Did you install it between the separator and air box? Or delete the seperator, install a air filter in its place, and route the line from the oil pan into the catch can and then into the air box? Or then vent directly to the atmosphere?

How important is getting the added vacuum when plumbed into the intake? I read that if venting to the atmosphere I'd have to open things up with bigger vent lines all around.

following. I also need to do something here. I was thinking about installing a breather that runs to the bottom on the engine cause there is already some sort of catch can ? Only thing i don't like about this is , i don't want to see a oil stain on the drive way when it sits overnight and that tube empties out. Almost rather still blow it back into the air box but filter it better.

Same problem. I've had the oil sep off the car and cleaned it out, along with making sure the drain hose is in good condition and not clogged. I see catch cans sold, but they're usually designed for PCV systems with a vacuum. I don't know that it would work correctly on this breather sort of rig the M21 uses. I was thinking of trying to stuff a pot scrubber into the oil separator to see if that would cut down on the oil vapor getting into the intake.

You don't think the existing setup on the M21 uses any vacuum? Hmm... I'll stick my thumb over the hole in the air box next time I start her up and see if I feel anything

I generally want to eliminate venting back into the airbox altogether, these fumes lower the cetane of diesel and with our engines pushing 30 years, I would think any little bit helps.

There are a couple of nice catch cans on ebay that include all fittings and hoses for $130 with two big 12 AN inlets. Or maybe three, so run the one from the valve cover, head, and block all into one catch can?

Not vacuum in the degree that gasoline engines have. I just don't know if the typical catch cans flow freely enough for the comparatively low vacuum levels that exist on this type of system. My concern is more that I'd like the intake to stop getting slimed up. When I had it off to do the injection pump, it was pretty nasty inside. I cleaned the intake and wiped out the ports in the head as best I could but not getting oil vapor in there constantly would have to help the situation.

Three years ago I installed a catch can/separator on a '11 X5 35d. Same deal, I was tired of the soot and CC blow-by mixing and coating the throttle body, EGR, intake manifold, swirl valves and intake ports with a black tar. A Mann Pro Vent was used along with 25mm oil resistant hose from the CCV Breather to ProVent back to the intake. Followed this guide for the install:
https://xoutpost.com/bmw-sav-forums/x5- ... rator.html

The mann filter is cleaned out every oil change with brake cleaner and replaced every two years. It no longer has the sludge of oil and exhaust soot mix caking the inside of the intake but that has been replaced with dry exhaust soot that still coats all of the parts. Now every 15k the EGR and TB is manually cleaned with brake cleaner and a can of LiquiMoly Diesel Intake cleaner hits the intake and swirl valves. Ideally I should get an ECU tune to block off the EGR ports and remove the soot but this thing still has to pass emissions in Colorado.

Do you get less visible smoke? When mine smokes its more of a blue cloud, not so much the black diesel soot thing. I can let it idle as long as I want, but until I open it up a few times it will smoke, so I think its oil laying in the intake getting sucked through. I'm guessing maybe the oil mist "condenses" when it sits and it turns into a puddle in the intake that gets sucked through when the engine starts moving some air. It doesn't go through much oil, about 1/2 quart in 5k miles, but it doesn't take a lot of oil to make a decent cloud.

maybe I should get my hands on another stock oil sep and see if I can modify it. I don't want to mess with the one on the car in case I fail at it.

Not so much less visible smoke since the X5's exhaust pushes through a DPF, catalytic converter and is spritzed by the DEF system. My main purpose in adding the Mann filter was for reducing the 'black tar' in the TB/EGR/manifold and head ports.

I had blueish smoke on startup on an e21 (m20 engine) and it turned out to be the valve seals. The seals would weep oil into the combustion chamber causing smoke on startup, or it also produced puffs of blueish smoke when coasting in 5th gear.

not impossible its valve seals. It was made in '84, sat for about a decade, and according to the odometer it has 190k on it. I'm not expecting it to be smoke-free but if I get some reduction along with no more oil goop in the intake, I'll consider it a bonus.

some poking around, no idea if its useful or not, but here you go.

OE part number is 11151285638, these are available for around $40
This seems to cross to a Cummins MerCruiser part number 801285638, which are available for about $80 because boat.
This is used on the MerCruiser 3.0 and 3.6L turbo diesel engine, which was manufactured by VM Motori for BMW Marine before BMW Marine was purchased by MerCruiser in the late 80s.

http://www.ybw.com/forums/showthread.ph ... ost3339357

has some further details on all that.

I haven't gotten far enough to see if there is an upgrade to the oil sep design that would be a direct physical fit to the old one but when I have some more time I'll poke around at it.