crankcase ventilation

[zaq123]

Also related question regarding How crankcase ventilation is designed on M20. Ok so there is a drain tube between the head and the crankcase as well as oil drain holes near cam rockers in the head. Valve cover has only one line routed right before a throttle plate. Correct me if I misunderstand the design:
1. Unlike in typical PCV design, the crankcase is not under vacuum (typically a vac. line from somewhere after TB) and it has no fresh air intake (typically the air box)
2. Crankcase venting is sealed to the engine and valve cover vent is just vent fumes
3. There is no vacuum in the system. There reason why folks report idle changes when removing oil fill cap because any air inlet created after stock AFM affects AFM door opening? For example if one plugs TB valve cover vent port and drops the hose from the valve cover vent to open air, no more idle changes on stock m20?

[zaq123]

any comments on this? There is no vacuum in the crankcase on M20 because it wants before throttle plate? Am I correct?

[digger]

there is should be only a very small amount of vacuum as it is pre throttle body so just whatever the upstream system creates which is very small.

[zaq123]

Im in the process of rigging up the oil separator from S62 p/n 11151406789. Basically want to make similar arrangement to S14 oil separator where its going to vent into the back of ITB airbox and drain into the dipstick tube. That oil separator will be plugged in to the airbox via grommet to minimize on running vent lines, similar how S62 has it mounted. Just need to hot steam shape the hose from the valve cover. Just want to make somewhat maintenance free system where one doesn't have to keep an eye on the catch can

[zaq123]

here is what I came up with. I didn't want to braze the oil return line on the dipstick tube as it would require painting the whole thing. Also Didn't want to separate the dipstick tube 325iX style with rubber hose and clamps as I wanted more rigid setup. -10AN 37' flared fitting did the job plus it lets change the angle of the dipstick tube as one needs it to be.
Had to bend 3/4 ID Gates hose (p/n 28478) with a steam and spring mandrel for a kink free routing around fuel rail, inj. harness and all those things. Basically hot steam through the hose with subsequent cooling in the bucket of cold water.
Also OEM dipstick tube is not exactly 5/8 to fit snuggly in the flaring tool so a couple of thin wall (0.016" wall) pieces of 5/8 aluminium tubing did the trick as it fits nice and snug around e30 dipstick tube for true 5/8 diameter.

Here is the result. Still need to get 90 degree AN to hose barb adaptor for the drain hose but you get an idea. Oil separator will be attached to the back of the airbox between runners 3 and 4 via grommet. 21mm ID x 2.5mm groove grommet works perfect with S62 oil separator and the aluminium Airbox backplate.

[tarkE30]

zaq123 i sent you a DM earlier. I have a similar setup (2.9L stroker w/ RHD ITB's) and want to know more about your crankcase venting solution and if it's working out. TIA!

[zaq123]

zaq123 i sent you a DM earlier. I have a similar setup (2.9L stroker w/ RHD ITB's) and want to know more about your crankcase venting solution and if it's working out. TIA!

yes it works great. I have some details about it in my post above. What details/specifics would you like to know?

[tarkE30]

Well, first, I think this is a really creative solution, and very well done. Honestly, there is very little information online or on forums about this specific application.

I was originally going to use a catch can with the inlet coming from the valve cover, but I couldn't figure out exactly where the outlet should go. The bitch tube and the dipstick tube both go to the crankcase, which is great - there will be a slight vacuum there. Others have said to connect the outlet line to the RHD vacuum block - but all of those ports/nipples already go to other places. And I was worried about oil vapor contaminating those vacuum lines.

This brings me to your solution. It's great because M20 dipstick tubes are cheap, and the risk is low. Your pictures are great, but there are a few things that I can't see.

Questions:

1. Do you need an oil separator if the line is going directly from the valve cover to the dipstick?
2. I am not running a plenum, just open trumpets, so i don't have an airbox. What would you recommend?
3. I assume you got the 5/8 thin-wall aluminum tube on McMaster, but did you just sleeve it over the dipstick tube - then flare them together? I've never used a flaring tool, but now I will go buy one.
4. I assume you just removed the length of the dipstick tube that is now occupied by the AN Tee fitting?

I think that's it for now, and thanks again.

[zaq123]

Well, first, I think this is a really creative solution, and very well done. Honestly, there is very little information online or on forums about this specific application.

I was originally going to use a catch can with the inlet coming from the valve cover, but I couldn't figure out exactly where the outlet should go. The bitch tube and the dipstick tube both go to the crankcase, which is great - there will be a slight vacuum there. Others have said to connect the outlet line to the RHD vacuum block - but all of those ports/nipples already go to other places. And I was worried about oil vapor contaminating those vacuum lines.

This brings me to your solution. It's great because M20 dipstick tubes are cheap, and the risk is low. Your pictures are great, but there are a few things that I can't see.

Questions:

1. Do you need an oil separator if the line is going directly from the valve cover to the dipstick?
2. I am not running a plenum, just open trumpets, so i don't have an airbox. What would you recommend?
3. I assume you got the 5/8 thin-wall aluminum tube on McMaster, but did you just sleeve it over the dipstick tube - then flare them together? I've never used a flaring tool, but now I will go buy one.
4. I assume you just removed the length of the dipstick tube that is now occupied by the AN Tee fitting?

I think that's it for now, and thanks again.

definitely do not connect return to the vacuum block of ITBs. It will create a giant vacuum leak you don't want. There is not much vacuum in the crankcase of any ITB engine as far as I know. Most OEM ITB setups vent the crankcase into ITB plenum which is obviously has almost no vacuum with a very minimal vacuum under WOT (if your airbox totally sealed etc.
How much blow by does your engine have? Is it oil you see for sure or just some oily moisture? M20 has a little more restrictive built it baffle than S14, by a little but still more restrictive. As you know, OEM M20 design vents directly to the intake manifold . So if your engine doesn't have excessive blow by, M20 cover plus oil separator similar to S14 will do the job on the healthy engine. So far I have almost 3k km on this setup and no signs of oil in the airbox at all.
I did vent to the atmosphere while figuring this setup and it was mostly oily moisture that I saw. Most catch cans and their tubing aren't positioned in the engine bay areas where 80C+ temperatures hence the moisture does not get burned off. I set my separator routing and separator itself similar to what OEM design does: close to the block and right above the block so it keeps any moisture away to create any milkshake.
BTW, that hose bending din't work too well so I ended up making a line out of pieces of hose with brass elbow to go to the separator, very short line. I can take a few pictures of the setup if you'd like. Let me know.

[zaq123]

Well, first, I think this is a really creative solution, and very well done. Honestly, there is very little information online or on forums about this specific application.

I was originally going to use a catch can with the inlet coming from the valve cover, but I couldn't figure out exactly where the outlet should go. The bitch tube and the dipstick tube both go to the crankcase, which is great - there will be a slight vacuum there. Others have said to connect the outlet line to the RHD vacuum block - but all of those ports/nipples already go to other places. And I was worried about oil vapor contaminating those vacuum lines.

This brings me to your solution. It's great because M20 dipstick tubes are cheap, and the risk is low. Your pictures are great, but there are a few things that I can't see.

Questions:

1. Do you need an oil separator if the line is going directly from the valve cover to the dipstick?
2. I am not running a plenum, just open trumpets, so i don't have an airbox. What would you recommend?
3. I assume you got the 5/8 thin-wall aluminum tube on McMaster, but did you just sleeve it over the dipstick tube - then flare them together? I've never used a flaring tool, but now I will go buy one.
4. I assume you just removed the length of the dipstick tube that is now occupied by the AN Tee fitting?

I think that's it for now, and thanks again.

and to answer your questions:

1. yes and the one that vents outside because you will basically seal the system and that line will be a smaller version go the bitch tube. Again as I mentioned above, You may create an issue with draining collected moisture into your oil because you can and its lines will act as a sort of crank vapour cooler. Can create lots of moisture too.
2. Id recommend to run an airbox to really get any advantage from your ITBs..
3.I think I got it on amazon. It's not sealing anything, flare does. It's there as a spacer of sort. It keeps AN fitting's cap more centred over the dipstick. Dipstick is a little thin walled for the tubing that AN fitting was designed for. Bit it's just a spacer so not critical at all.
4. Yes, once set and done, new dipstick needs to be exactly long as before. So you need to minus AN height and plus how much flare will take away from the tube. I have a piece I cut out somewhere if you want me to measure it. I also recommend buying a spare M20 dipstick on eBay or whatever so you are not out of dipstick while you are doing it or if you mess up. They are cheap and plenty

[tarkE30]

Thanks for this. and appreciate the explanation. I am still learning about this level of engine detail, so forgive my ignorance - I may have misspoke. Now I understand that crankcase = slight positive pressure (can create blowby), valve cover vent = slight negative pressure (?).

I was told by the crew that tuned my car that a catch can will make the engine "run healthier" and eliminate the vapors. But they didn't go into detail about the installation.

Right now, I have the valve cover with a filtered vent (see pic), but it constantly seeps oil and smells strongly of oil vapor. So my first course of action is to run that to a catch can and move the vent to the catch can (vent to atmosphere). I already bought the catch can so that should be an easy, temporary install. I do like what you did to close off that loop entirely and drain any blowby back into the crankcase.

I have no idea how much blowby i am getting, as i don't think there is any way to see evidence of that?

My goal is to allow my engine to "run healthier". Seeping oil and vapors is not acceptable long term. I think your setup is the cleanest. I can CAD model most things in Fusion360 and have access to all kinds of 3D printers and high-temp materials, so maybe there is a 3D printed solution.

[Maybe Magpie]

here is what I came up with. I didn't want to braze the oil return line on the dipstick tube as it would require painting the whole thing. Also Didn't want to separate the dipstick tube 325iX style with rubber hose and clamps as I wanted more rigid setup. -10AN 37' flared fitting did the job plus it lets change the angle of the dipstick tube as one needs it to be.
Had to bend 3/4 ID Gates hose (p/n 28478) with a steam and spring mandrel for a kink free routing around fuel rail, inj. harness and all those things. Basically hot steam through the hose with subsequent cooling in the bucket of cold water.
Also OEM dipstick tube is not exactly 5/8 to fit snuggly in the flaring tool so a couple of thin wall (0.016" wall) pieces of 5/8 aluminium tubing did the trick as it fits nice and snug around e30 dipstick tube for true 5/8 diameter.

Here is the result. Still need to get 90 degree AN to hose barb adaptor for the drain hose but you get an idea. Oil separator will be attached to the back of the airbox between runners 3 and 4 via grommet. 21mm ID x 2.5mm groove grommet works perfect with S62 oil separator and the aluminium Airbox backplate.

This is cool as hell. Stupid question, but do you think running just metric barb fittings would also be feasible instead of AN lines? I know AN has advantages, but I like keeping my car all metric and not needing the special wrenches, and do you think this would still work out and fit on the stock single-TB setup? I'm thinking I might be able to drill out a hole on a dipstick tube, have a guy I know weld a nut on there as I imagine it's too thin for tapping, screw in a threaded barb fitting to the nut, and run a hose that way up to a catch can.

Also, Tark, who made that neat little 2.8 plaque that mounts to where your intake was? That's a really slick detail.

[tarkE30]

i was thinking of something similar to avoid the AN fittings. through my work. i have access to machinists & prototyping suppliers who could effectively make a thick, stepped sleeve that would have perpendicular (preferably metric) threaded hole. the cut dipstick tube ends would bottom out on the steps. just a(nother) thought.

as for the little 2.8L plaque made that in Fusion 360 and printed it with high-heat filament. then painted it with high-heat silver rattle can paint.

[tarkE30]

zaq123 i am completely missing what you refer to as an “airbox”. do you mean a plenum?

[varg]

With such a setup I'd dump it into the exhaust after it goes through an air/oil separator, provided the exhaust is free flowing enough. There are commercially available kits with fittings and check valves for this purpose.