DIY: Dual Catch Cans with Air/Oil Separators... On the CHEAP!

Sh0velMan

Attached a photo of what the internal tubes look like, hopefully answers some questions about how the cans perform.

After about 500 street and dyno miles, there is a good amount of oil in the can and zero in the tube exiting the can. The oil on the paper towel is from the inlet tube (long one).


There will be pictures before too long, but here is a text-only version of this DIY.

If you need help using this DIY to set up your own system, shoot me a PM and I'll give any assistance I can!


The purpose of this DIY is to give a guide on how to make an affordable oil/air separating system for our cars. There are other documented methods of accomplishing the same task, and those methods are awesome, but you can spend literally hundreds of dollars trying to accomplish this simple goal (because our car needs two of everything!). This was unacceptable to me, so I engineered a way to accomplish 99% of the work using <50% of the cost.

I know it seems like a lot of words and therefore a daunting task, but it really isn't.

Difficulty: 5/10 - Light fabrication work using hand tools and a Dremel.


What you will need:



Parts:

• 2 x Catch Cans
  • I used Godspeed Universal Racing Oil Catch Can - Godspeed Universal Racing Oil Catch Can Tank Oil Reservoir Tank Gold Color : Amazon.com : Automotive
  • I picked those because they're cheap and Prime on Amazon for free shipping. Color is meh.
• 8 feet of 10mm Silicone tubing
  • I bought from here: Aluminum Pipes, Stainless Steel Pipes, and Exhaust Parts
  • I did it with 7 feet, but it was tight. Get 8 or 9 feet to be safe. It's cheap.
• 1 foot of 3/8ths inch ID (inside diameter) brass tubing

Tools:

• Basics (Screw driver, needle nose pliers for clamps etc)
• Dremel (or other rotary tool)
  • Cutting Wheels
• Hack/Band Saw (Or Tubing Cutter!)
• Hand File
• Wood Block
• Mallet or Hammer
• An allen wrench that fits the little screws on top of the catch cans.
• A 1/4 or 5/16 drill bit
• Razor knife
• ~200 grit sand paper
• Sharpie marker

Step 1:

1. Take the catch cans apart by removing the allen head screws on the top of the inlets as well as removing the plug in the bottom.
   
2. Use some needle nose pliers to clean up any obvious metal imperfections inside and repeat to yourself: "They're super cheap, they don't need to be pretty on the inside and out".

Note: I like to flush them out with some brake cleaner, just wipe it off of the exterior pretty quick, dunno how the finish will like brake cleaner. You can use isopropyl alcohol if you prefer to play it safe.



Step 2:

1. Cut your 1 foot of brass tubing in half using your hack saw (or band saw if you have it).
2. With each 6 inch section, cut it into two pieces: 1 x 2", 1 x 4".
3. Use your metal file to clean up the ends of the tubes where you cut.
4. Flare the inside of your 4" sections of tubing using your pliers. Do this by holding your needle nose pliers in your hand tightly so that it has a pointed end to it. Flare the tube by working the tube onto the end of your pliers, spinning it as you work the pliers into the tube, it will expand the end of the tube slightly if done right. A slight flaring should be visible. Do this ONLY to one end.
5. Do the same with your 2" sections.

Step 3:

1. Find the inlet block with the longer of the two inlet pipes (internal), one will be slightly longer than the other. Place the non-flared end of your 4" section of tubing against the wooden block. Hold the inlet pipe of the inlet block to the flared end, you may be able to start the insertion slightly. Tap the inlet block with your mallet or hammer to press the inlet pipe into the flared end of your tube. Be gentle, take your time, brass is very soft and you can goof it up easily. Sometimes some machining oil or any other kind of light lubricant can help get the brass tube onto the inlet pipe.
2. Repeat this task with the other 4" tube and the other inlet block with the longer pipe.
3. Do the same now with the 2" sections and the remaining inlet blocks.

Step 4:

1. Clamp your inlet block in your vise or hold it with your GLOVED hand.
2. Using your Dremel with a cutting wheel to cut a series of parallel slots along the length of one side of your 4" brass tubing. Start about 1 inch down from the top making a slot every 2mm or so. Repeat this for the opposite side of the tubing.
3. Use your Dremel to cut a pair of slots in the very end of your tube, in line with the axis of the tube itself to create an X-shaped pattern in the end of the tube (when looking at it edge on, down the tube). Make the slots about a quarter inch thick. This will create quarter-circle tabs along the bottom of the tube.
4. Use your drill bit and razor knife to clean up the various slots you've cut. Slide the drill bit up and down the interior of the tubing, holding it against the edges. This will clean up the inside of the tube in short order. Carefully cut any flakes of metal hanging on to the edges with your razor knife. Brass cuts very easily, just spend a little time cleaning them up and you'll be good. For the exterior, you can cut the edges with your knife or use your sand paper. Take care not to bend the tube.
5. Use your needle nose pliers to fold in the tabs created on the end of the tube. The idea is to fold one over another working clockwise so that the tube has a "solid" appearance to the opening. Don't spend too much time trying to make the end perfectly flat or anything, you'll just deform the tube end and it doesn't need to be solid or flat. The idea is to break up any airflow still flowing down the tube by the time it reaches this point.
6. Go over the exterior of the tubing with your sand paper and smooth out any sharp edges you find.
7. Repeat these steps for the other tubes. For the shorter tubes, start about 1/2 of an inch below the top when making your slots.

Step 5:

1. CLEAN YOUR PARTS THOROUGHLY WITH ALCOHOL OR OTHER SOLVENT.
2. Using your Sharpie, mark the exterior connectors (the brass bits that you hook the lines onto) accordingly. Do this on the outside, where you hook your silicone tubing to so that you can see it before you install the tubing and can keep it straight what goes where, but can't see it once the tubing is installed:
   • Long brass tube = I (for 'In')
   • Short brass tube = O (for 'Out').
3. Reinstall the tubes into the cans. I like to put the 'In' pipes on the center-most hole and the 'Out' on the exterior-most. Tighten them down SNUGLY with your allen wrench.
4. Reinstall bottom plug.
5. Check for leaks. This is basically just, cover one of the inlet pipes with your thumb and blow into the other one. If you hear hissing or a noticable loss of pressure, you may need to figure out where it's leaking. Chances are, it's the clear tubing on the outside of the can. The way those fittings work is, try and shove the clear tube INTO the black fitting, then pull OUT on the blue ring. It may click or something, but even if it doesn't, if the blue ring is flush against the black fitting, that's where your leak is. Make sure the tubing is forced into the fitting and the blue ring stands proud of the fittings on both ends of the clear tube and re-test for leaks.

Step 6:

1. Mount your cans wherever you like. With stock air boxes, I'm not really sure where you would mount them. With almost any aftermarket setup, you can mount to the old mounting tabs the stock boxes used. See my engine bay photo for reference. I used the crappy brackets and hose clamp arrangement that comes with the cans. I just added some rubber sheet between the can and bracket. (I did have to cut off a mounting bracket on my Nismo CAI tubes, it was useless anyway.)
   • See my engine bay photos for reference.
2. Connect silicone tubing from the PCV outlet nipple on the forward half of the cylinder head cover to the inlet you marked with the 'I'.
   • Find this nipple by tracing the path of the OEM rubber tube from the nipple hanging off the front edge of the intake manifold.
3. Connect tubing from the 'O' nipple to the vacuum nipple on the front edge of the intake manifold. There's one for each side of the engine.
   
4. Repeat for the other side.

You're done!

Start it up, make sure it idles and drives like you expect. Check the cans by removing the inlet and outlet pipes with an allen wrench if you need confirmation that oil is being separated. If done right, you'll see evidence of oil dribbling down the one marked 'I' but no evidence at all on the one marked 'O'.

If the car idles rough or tries to die, you've got a vacuum leak. Either your lines aren't secure or the cans have a leak.

Fully installed reference image:

Attached Images

WP_20130927_005.jpg (206.9 KB, 845 views)

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Chuck33079

Awesome. Thanks

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Sh0velMan

NP. Updated it with grammar and formatting fixes. A lot more readable.

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MyKindaGuise

Came for the DIY and stayed for that sexy aerospace gold foil.

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Chuck33079

On other cars I've used stainless steel wool in the catch can to give the vapor something to condense on. Does the way you build the inlet pipe take care of that, or would some additional filter media help as well?

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Sh0velMan

I had intended to use such a setup, but the opening on the bottom of these cans is so tiny, I was not confident that I could get the media in without causing it to separate into small bits that might get ingested.

The more complex inlet and outlet internal piping seems to be doing a well enough job that I don't think it's necessary.

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Chuck33079

Sounds good. How much oil do you see collected in the cans? Do you see any oil in the intake tract after the cans?

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Sh0velMan

Well I didn't take off my intake manifold and clean it or anything ahead of time, but what i can say is this:

When I pulled the inlets out of the can, the one marked 'I' coming from the crankcase had oil dribbling down it and had obviously dripped oil into the can.

The one marked 'O' that leads to the intake manifold was completely dry, not one spec of oil on it.

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Chuck33079

I'll probably go with clear hose on the outlet, and that way we'll know for sure.

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Sh0velMan

Sweet. Post a link with where you find appropriate tubing, just for reference!

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Chuck33079

I'll have to do some searching. I know it's out there. Turboxs had some nice clear PCV hose with a wire matrix in it with their Subie FMIC kits. Summit or Jegs will probably have some if I look hard enough.

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Sh0velMan

McMaster-Carr

Semi-clear white, 3/8ths ID, 5/8ths OD would probably work. You should be able to, at the very least, shine a flashlight through it and see the oil. It's not too expensive either.

This is the clearest you can get and still have a temperature rating that I would feel comfortable with (You need ~250 deg F, IMO and all true clear stuff is sub 200).

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Chuck33079

I just called TXS about theirs, and he's going to check out where he gets it and call me tomorrow. I'm partial to the reinforced stuff, especially on a boosted car.

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Sh0velMan

Ah, it's only rated to 10psi @ room temp, though I HIGHLY doubt you'd have any issues with it coming apart.

Lemme know what you find out! Specifics like what exactly it's made of would be helpful.

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Sh0velMan

Ah here you go, scroll down to high pressure white: McMaster-Carr

It is semi-clear as well.

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