Would a gizmo like this help?

[kang]

I’m toying with the idea of adding some sort of oil separator/catch can to the line from the oil tank to the intake manifold. Here are a couple of examples from other cars, but you’ll get the idea:

http://www.f150online.com/galleries/pictureview.cfm?pnum=110810&anum=7528
http://elantragtclub.tripod.com/elantra/id405.html
http://www.mirage-performance.com/sonata/CatchCan/
http://www.mustangweekly.com/2004/september/newproducts/NP09_01_.ASP


In theory, it would catch oil and water vapor before it goes into the engine. This would help keep things clean: the intake track, the valves and the combustion chambers. I also understand that a little oil vapor increases the combustion temperature which can lead to pinging.

Has anyone tried anything like this on an air-cooled flat 6? None of the cars listed above have a dry sump system with a big oil tank. I don’t know if that makes our cars more or less likely to suck oil into the intake. Any other thoughts? Any harm to the engine? For 15 bucks, it might be worth a try, and if it doesn’t catch anything, throw it away (or sell it on eBay!).

PS. You can do a google search on “PCV catch can” or “PCV oil separator” and find many more examples of these. I’ve also seen complete kits on eBay.

[MotoSook]

It wouldn't hurt. The hose between the oil tank and the intake draws a lot of oil vapor. Just try loosening the hose clamp on the intake side for a few days of operation...you'll soon see oil condensed around that clamp and the surrounding surfaces. The PVC catch will see more liquid than vapor, but in the case that you use the separator on your vapor line from the tank to the intake, you might see very little liquid collect in the separator unless you over fill your tank...or the separator is chilled somehow causing the vapor to condense in the sparator.

Again, it wouldn't hurt, but unless you over fll your oil tank....it'll just look out of place in your engine bay...you could tuck it behind the engine...

[Craig 930 RS]

I use a Mobil 1 bottle tucked in the left forward portion of the engine compartment --- works GREAT!

[911pcars]

My thoughts:

They all use hose that may be a little too small for the volume of air/oil mist our engines generate, especially at high rpm. The larger the hose, the lower the gas velocity which helps separate air and oil better.

http://www.f150online.com/galleries...10810&anum=7528
http://elantragtclub.tripod.com/elantra/id405.html
http://www.mirage-performance.com/sonata/CatchCan/
http://www.mustangweekly.com/2004/s...ts/NP09_01_.ASP

I would prefer both larger ID hoses and larger volume container to separate and store coughed up oil. For a ready-made unit, it might be worth a try, but if crankcase pressures can't vent fast enough to your system, expect oil leaks to the outside world through the myriad of potential oil paths.

Sherwood

[RoninLB]

Home Depot washing mechine discharge bent hose works well for me. No kinks.

[kang]

Hi Sherwood,

That’s an interesting point about the ID of the hoses. But they all seem to be about the same diameter as the hose that is in there right now. I did a bunch of searching on this, and some people mention that the filter itself could block the flow, but no mention of hose diameter. Still, your point is a good one. Some people have removed the filter so that the catch can works more like a shop-vac. It wouldn’t catch all the oil, but it would catch most of it. But I’d hate to cause an oil leak if the pressure couldn’t vent. I saw no mention of this in all my searching.

Also, I thought that suction from the intake is what pulled the air and vapors in, not pressure from the crankcase. Of course, the two are related. With more revs comes more pressure and more vacuum. I think the “balance” of the stock system is such that there is typically negative pressure in the crankcase, rather than a small amount of positive pressure. This negative pressure is supposed to help the rings seal. If there is enough extra negative pressure in the crankcase, reducing the flow via small ID hoses or a filter wouldn’t increase the pressure enough to cause leaks. The rings might not seal as well, though.

Unless it is going to cause harm to my motor, spending <$15 to try this out doesn’t seem like much of a risk. I could run it for a month or two to see what it catches. If the bottle is dry, toss it. I’d also have to remove it for smog inspections. It would fail the visual.

I thought about Ronin’s or Craig’s solutions, just putting a vent or bottle there. But as I mentioned above, the vacuum is supposed to help the rings seal.

[kang]

I did some more searching on these and here’s an update on what I found.

They install these things in some pretty big motors, like Vettes, so I doubt it would impede any flow in our little 3.6 engines, even running 8,000 RPM. Oops, I meant 6,800. A couple people mentioned the possibility of oil leaks due to too much pressure, but nobody reported actually getting a leak.

The filter I’m looking to try flows 21 SCFM at 90 PSI: http://store.yahoo.com/ekimco/mp5138.html

Here is a good discussion on them from a Corvette forum:

http://forums.corvetteforum.com/showthread.php?t=875028&page=1&pp=20

And an Evo forum:

http://forums.evolutionm.net/showthread.php?threadid=51997

Here are some long term reports, over a year of use:

http://www.ptcruiserlinks.com/forum/topic.asp?TOPIC_ID=11642


I found lots of other forums where these have been installed on lots of different cars. Varying results with how much oil they catch. I have a feeling I’ve got some carbon build-up in my cylinders and this oil might be a source.

If the cheapie filter works, I could install one of these real ones:

http://www.accmachtech.com/pcvcatchcans.htm
http://lowrider.cardomain.com/item/GRE12003510

[RarlyL8]

You can purchase a K&N filter that fits right on the oil tank vent tube. They are standard equipment when installing Webers to any 911 engine.

I use a replaceable breather filter from AutoZone. I just looked at the stock units available and found one with the correct vent tube size. $3 and you throw it away when it gets dirty.

[randywebb]

Here's the deal with hose (or pipe or tube) sizes:

the resistance to flow thru any tube increases greatly (non-linearly) as the dia. decreases (this is why partial blockage of a blood vessel in your body is so dangerous - resitance goes way up and so does pressure, then the oil line ..oops blood vessel... splits and ... y'all dead).

As resistance increases, the velocity of the flow goes way down, so the oil/air mix tends to stagante and the oil drops out of the mix -- somewhat like water in the atmosphere.

so big hose = better

[MotoSook]

I agree that going to a smaller hos ID is not the preferred path....

..and I don't want to change the topic, so this is just for Randy w/r to the analogies above...internal compressible flow, saturation, critical pressure....just think about it.

[RoninLB]

Originally posted by kang

I thought about Ronin’s or Craig’s solutions, just putting a vent or bottle there. But as I mentioned above, the vacuum is supposed to help the rings seal.

I would have installed just a hose dumping underneith except that when decelerating in gear a negative atm is produced sucking dirt into the crankcase afaik/no hard info.

"You can purchase a K&N filter that fits right on the oil tank vent tube. They are standard equipment when installing Webers to any 911 engine."
.. exactly. And adding a length of up angle hose reduces moisture escaping big time.

and what? no mention of friction increasing using same discharge and smaller hose.. after all air & fumes is a liquid.

[randywebb]

Duly thoughted...

or should that be: Dully thoughted?