In a post about crankcase/oil breathers a while ago, I learned from Racer Chris that the breather set up on my /4 is incorrect. That being that it's currently running to the intake manifolds, and not into the carbs as it should be.

I'm planning to reroute the lines to the carbs and add a home made filter in the line to collect oil vapor. It's a light duty job that I can tackle as I'm awaiting the surgery on my shoulder. So I'm just wondering what type of material I should use for the filter? One thing I thought of is steel mesh (not wool).

To make the casing I'm going to pick up a 1" aluminum conduit nipple and caps for either end This way one of the caps can be removed to clean the filter from time to time. I'll drill holes through the caps and insert nipples for the hose to connect. I'm going to try to place it as close to the original breather as possible to allow the oil vapors to drain back into the crankcase.

Sound like a good plan?

Had a similar problem - I went this route ...

http://cgi.ebay.com/ebaymotors/ws/eBayISAP...718963&rd=1

how do you plan to vent them to the carbs?

.

That looks like a nice system, but for the sake of experimentation and pure curiosity, I'm going to make this myself. But if it doesn't work out, I'll pursue other options.



Racer Chris told me I should route the hoses back to the air cleaners, behind the filters and directly into the carbs. The filters I have are a flat box type filter, at a guess [cuz I can't go look right now] about 4" wide by 6" long by 2" deep. Chrome plates, about 24 gauge, are on the top and bottom to hold the filters into place. I'm planning to take the nipples that are currently in the intake manifolds out, plug those holes, then drill through the top plate of the air filter and secure the nipples w/ a nut on the underside to provide more stability. I may have to cut them down a bit as they're about 2 1/2" long so as to prevent clashing w/ the hood, but this should work.

As for filter placement, I'm going to try to mount it directly on top of the original breather. I'm not sure how just yet- maybe purchase a second nipple so as to screw into the existing breather hole atop the apparatus [or whatever you want to call it- i'll provide pics of this when i get a chance]. I'll work out the details when I get a chance.

So... thoughts on the material? Steel mesh good/bad? Other options?

One important factor is the chamber you put the filter material in. It has to be large enough that the gas velocity slows for the oil mist to separate.

Okay. Like I said, I was planning to buy a 1" aluminum nipple for the chamber, then caps to place on either side. Then drill through the caps to allow connections.

Is that big enough, or do I need to go bigger?

Well, I dont have any empirical evidence but would like to see the chamber have at least 10x the crossection of the hose leading to it. A 1 " nipple is only about 4x as compared to a 1/2" id hose.

Piledriver on Shoptalk forums is big on those stainless steel woven pot scrubbers. Apparently the VW guru -Bob Hoover- figured it out that SS pot scrubbers make excellent air/oil separators.

He runs "Chore Boys" brand.

Ken

I'll have to measure the hose that's currently in use... if I remember correctly it's 7/8" OD and 5/8" ID but I'll have to double check that... now I suppose you're going to tell me I don't have the right size hose, aren't you?

AREN'T YOU!?

Well, since you insist - you don't have the right size hose.

can't you use the stuff they use in racing fuel tanks ?

This is similar to what I was thinking of using. A steel mesh/wool type material. Seems the best option as a fiberous material would soak up the oil rather than just collect it. I don't know that I'd want steel wool tho- that could possibly break up over time and send little pieces back through the intake system, which would be bad.




I don't know what you're talking about...


Okay, so here's some pics of what the current set up looks like.

This is the current breather. I dunno if it's stock or custom, but it's just a rubber elbow coming out of the oil breather base. There's no valve or anything inside it.
Click to view attachment

This is the placement I'd like to have for the filter. Ideally it would just attach in the same place as this one but I don't know if that will work just yet. It depends on the size of the chamber I need. And the caption in the pic says there or at a 90* angle, but I just realized that won't work. It would have to be a slight angle, no more than a 45* bend, otherwise the oil wouldn't drain back into the case.
Click to view attachment

Here's a side shot of the current air filters. Like I said before, they measure about 6" long by 4" wide by 2" deep.
Click to view attachment

Here's a top shot of the air filter. Per Racer Chris, I would drill a hole inside the circled area to allow the flow directly into the carbs, behind the filter.
Click to view attachment

Here's where the current set up runs to on the intake manifold. I'm going to remove the nipples and plug the holes on the intake, then use the nipples to attach the hose to the top (or bottom) side of the air filters, then use a nut on the other side to secure and stabilize the nipple.
Click to view attachment

This is a rough blueprint of what my filter is going to look like. Originally I was going to just stuff the filter material into the chamber, but then I wondered about the possibility of the material somehow working its way into the hose and/or the breather base, so I decided that adding a screen of sorts would help hold it in place and prevent that. The chamber and caps will be aluminum conduit fittings. I'll drill and tap the caps to allow for a nipple to be inserted... at least on the top. Depending on if I can get away with mounting it directly to the base or not will depend on how I set up the bottom.
Click to view attachment

So I guess the only thing to figure out is what size chamber I need. The hose I'm using is 13/16" OD and 1/2" ID. So, Racer Chris, how do I calculate what size chamber I need?

And does anybody have any thoughts/suggestions on what could be done to make this system a little better?

I don't really know how to calculate that, but what I suggested was a crossection of 10x the hose crossection. The reason for this is to suddenly slow the gas flow velocity and cause the oil droplets to separate from the vapors. Crossection (area) equals pi*radius*radius.

umm, buy a properly engineered kit designed and built by some one who knows what he is doing?

Chris:
You have obviously done the research and built the correct item for those who want the best.

Now you should facetiously offer one made from a small can (tuna?) for the readers here that want one but aren't your customers anyway.

Horse hair could work as a filler. Ed might want to offer some hair! (Hi Ed)

-Mike

Thanks for the formula Chris.

And as for buying one from "someone who knows what he is doing," or being a guy "who wants one but isn't his customer" ... well, it's like this- we don't all have money to just throw around for every little thing. And I'm not saying your system is ridiculously expensive Chris- I don't know what you want for it; in fact I've never even seen what you offer. But this is a relatively simple thing that I can make myself- all I was asking for is what material to use for the filter and how big the chamber needed to be. It may only amount to a few dollars but I'm still saving money making it myself.

Besides, it's not so much about money as it's just a curiousity thing. I want to make it myself to see how well it turns out. If it doesn't work that well then I can work with it until I get it right. This is my first 914 and I can't learn anything if I'm just going to up and buy the shit I need as opposed to experimenting and trying to work it out on my own.

I have a bunch of fuel cell foam and have used it in my own breather projects in the past. It is a good choice IMO and I would be happy to send you a piece for your project.

Hell of an offer Chris that fuel cell stuff aint cheap