Anyone running an OSV catch can?

[Jdmark7]

I've seen a lot of catch can set ups on e39's, anyone running one on an e38? I just changed my rear osv and still getting smoke on startup and oil in the mani, so interested in a catch can: I love cheap smart fixes.

Update: I decided to try one out. I did everything with an extra OSV cap I had, no need to remove the whole rear OSV unit. Once I tapped everything it was as simple as clipping the new cap on.

Tapped an outlet bung and sealed in liquid gasket:


For plugging the inlet to the intake manifold I used a nut and bolt. The nut on the inside was a mm or so away from the intake inlet so I had high temp gasket maker fill the void. Was airtight on my spare OSV plate that I tested it on. Not pictured is the outside ring of a new OSV gasket that I trimmed off. One tab is broken but it still holds.



The whole kit including pretty corny looking catch can I found on craiglist. Only thing not pictured is a small section of 3/8" hose used for adapting purposes.



Finished product, I will put some miles on and see how it does in this current vent-to-atmosphere setup with no drain. Total spent about $40 and after a few starts there is no more smoke, I still have the stock setup so I can quickly revert back if any issues.

[xboss]

Doesnt seem like a smart fix. Oil in the intake sucks.

[Jdmark7]

The catch can would resolve oil in the intake, I meant that my new osv is still not filtering the oil and a catch can would fix it so id like to see others set ups

[CharlesAFerg]

I've seen a lot of catch can set ups on e39's, anyone running one on an e38? I just changed my rear osv and still getting smoke on startup and oil in the mani, I love cheap smart fixes.

Probably the front cyclone OSV has failed, as apposed to the rear. My car does the same thing.

[Jdmark7]

Exactly, and for ~$100 you can run a catch can either in line or after the first osv to take all of the blow by.. Trying to see if anyone is running a catch can instead of ripping apart the engine

[Cobrajet429]

I was thinking about it because I was still getting a lot of smoke after replacing the rear OSV. I changed the OSV for a second time and now get 0 smoke. Did you use an OEM OSV plate? I would also suggest replacing all the intake gaskets because a bad intake seal could also cause the OSV to not have enough suction to pull enough pressure. They are cheap and easy to do and would be worth a try before you try to re engineer an already bad system.

[Zedbimmer]

i have a catch can, easy setup.

http://forums.bimmerforums.com/forum...U-intake-oil!-!

[s14b23]

That's quite interesting: -osv ever goes bad and it "spits out too much oil"??? But why?? Does it have spitter lol Have you ever seen osv design?? There is nothing there what can go bad unless it's fully clogged, but in this case it would be an emergency. -changing osv makes things better?? Why!?? -in m54 osv and ccv are together one piece design and if M54 burns oil, no ccv osv or any other parts can fix it, unless you replace CONTROL rings. In my experience (I had a few m62, n62, m60, m54, s54) if your intake manifold is full of oil and ccv is in good shape- the answer is in control rings and sometimes valve stems.
Catch can will definitely help and even sometimes can help unclog control rings bc of less oil gets into the camera therefore rings.

CCV design depends a lot on vacuum therefore any small tiny vacuum leak will reduce vacuum in the ccv and therefore it won't close on idling causing too much oil in the intake. And don't forget paint on valve covers goes bad causing uneven surfaces therefore vacuum leaks.

[Jdmark7]

Updated my original post

[deathsled]

Wait, so you have no vacuum drawing on that? It's my understanding that these engines don't particularly like that.

[Jdmark7]

No vacuum, VTA. I figured crank case pressure was enough but would love to hear more opinions. I've seen some VTA setups before on M60-M62 so didn't know that might be an issue.

[deathsled]

Well the system is designed so that you have vacuum in the crank case. With VTA you have no vacuum and probably are allowing a bit of pressure to build. It's definitely worse for your seals, but how bad? Who knows.

[Haadkoe]

What about adding a vented oil cap as well, to help relieve pressure? That's how they did it back in the day anyway, I believe.

Barbed fitting and a mini cone filter on the fill cap should do the trick, I'd think. Car will probably smell of open exhaust and hot oil in traffic and when first parked though.

Interested to hear the thoughts of those more experienced.

[Cobrajet429]

What about adding a vented oil cap as well, to help relieve pressure? That's how they did it back in the day anyway, I believe.

Barbed fitting and a mini cone filter on the fill cap should do the trick, I'd think. Car will probably smell of open exhaust and hot oil in traffic and when first parked though.

Interested to hear the thoughts of those more experienced.

IMO, an even worse idea than the catch can. These cars are designed with a closed crankcase that is far from ideal, but to work properly they need to stick with the same configuration. It is possible to get a brand new, bad OSV. Also, since the system works off of vacuum, intake leaks can cause it to smoke as well. As stated earlier, my car smoked a lot worse after replacing the OSV the first time but has not smoked a single bit since I replaced it the second time. With the rear plate off blow through the hose going to the front OSV, if you can blow through it, it is probably OK.

[daytonatrbo]

So, the drain on your osv is gummed up and now you have a catch can on the line that should be the "cleaned" air returning to the intake, which is the source of vacuum that makes the system work correctly.

Not only are you allowing metered air out of the system, but you are removing the vacuum source that is supposed to make it all work.

The only time you catch can will receive oil is when the crankcase and therefore valve cover is pressurized, which is an undesirable situation.
So your solution to that is to vent the oil cap, which fixes the pressure problem but also removes any motivation for the oil to end up in your can and potential for further leaks of metered air.


Those old crank vent systems that you are trying to reproduce have a tendency to spew a lot of oil vapor into the air. That's why they started sucking that vapor into the engine and burning it off. The system that came on your car is the result of decades of evolution and engineering. You aren't going to do much better than a cyclone separator valve and it designed to keep metered air in the engine.

Am I missing something? This seems like a terrible idea.

[Haadkoe]

How and why does vac motorsports run a catch can vented to atmosphere on some of their builds if it is such a terrible idea?

Personally, the idea of pumping oily vapor (or worse, straight liquid oil when the internal osv completely flakes out) dirctly into your intake manifold sounds much less desirable to me. Pre-detonation is a bitch. Hydro locking an engine on oil, also a bitch.

The idea of returning blow by gasses to the intake tract was a direct result of emissions requirements. The oily vapor is burned off by the engine, and cleaned by the cats... which ain't great for the cats either, but I digress... Take emissions out of the equation, and how bad of an idea is it, really? I dunno... But I do know other "tuners" have been doing it with obdII vehicles for years.

Now there is the question of unmetered air escaping the system, and the potential for unmetered air to enter the system. Would either of these things cause enough of an issue to be problematic or throw a fuel trim cel? Again, I dunno.

If unmetered air entering the system actually becomes a problem, then I'd think putting a traditional inline pcv valve on all of the vents should keep unmetered air out, while allowing crankcase pressure to escape. Conversely, if unmetered exhaust escaping the system becomes an issue then we're back to square one; but it begs the question: how are others doing it successfully?

Kinda playing devils advocate here, because I really don't know for sure, but I'm in for the discussion.

(PS: In the interests of equal pressure, I'd think a breather filter added to both valve covers would do for the top, while the ccv tube routed to a can and vented to atmosphere would handle the bottom. Again, just speculation)