DIY catch can for $27 and a little time...

[shines]

I’m about to buy a catch can, but was on the verge of building one. So, I figured I’d go ahead and build it to share with those that may not have the budget to buy (they are quite expensive). I decided to build one using materials available at any hardware store using a few simple tools.

I’ve used this design in the past with good success, it will serve the purposes of most anyone and will collect as much crank case goop as many commercial ones.

The Design
Basically the design is a can that's about 6" tall and 2.5" in diameter. At the top there is an inlet nozzle and outlet nozzle. On the bottom there's a drain pet****. On the output end of the inlet nozzle a cross drilled metal tube is attached that serves two purposes,

1. Increase the distance between the inlet and outlet flow points. The larger this distance, the more effective the catch can is because the crank case vapors have more time to condense within the container.
2. Provides a cooler surface over which the crank case vapors pass, helping them to condense into droplets.

The Material
The body of the can will be made of three PVC fittings, coupled together with short pieces of PVC pipe to make it appear as seamless as possible. PVC has a melting point somewhere between 320 and 680 degrees Fahrenheit (depending on the quality of the raw material), which should be fine for most applications but care should be taken to mount the can as far away from the engine as possible. An advantage of PVC over a metal container is that it's a poor heat conductor, this allows the can to maintain a significant temperature differential internally relative to the engine compartment. This will enhance the can's ability to condense the crank case engine vapors.

In the following picture you'll see the parts/items needed to make your catch can, they are:

• 1 - 2" ID PVC pipe coupler ($1.50)
• 2 - 2" ID PVC pipe cap ($3.00)
• 2 - 2" OD x 1.5" long pieces of thin walled PVC pipe ($1.50)
• 2 - 3/8" x 1/4" Bronze Hose Barb Elbow ($4.00)
• 1 – 1/8” x 4” NPT Threaded Pipe ($2.00)
• 1 - 1/4" Bronze Pet**** ($3.00)
• 1 - Can Dupli-Color Bumper Coating ($7.00)
• 1 - Roll of thread sealing tape ($2.00)
• 1 - Small can of PVC cement ($3.00)

The Tools
You'll need the following tools,

• 7/16" Drill bit
• 11/32" Drill bit
• 1/8" Drill bit
• 1/8" NPT 27 Tap
• 1/4” NPT 18 Tap
• Drill
• Hack Saw

Making the Body
The body of the catch can consists of the two PVC pipe caps coupled to the PVC pipe coupler using the thin walled 2” OD PVC pipe.

1. Using the 2” OD thin walled PVC pipe, cut two pieces approximately 1.5” long.
2. Apply PVC cement to the inside wall of one of the PVC pipe caps and insert one of the cut pieces of 2” OD pipe half way in (0.75”)
3. Apply PVC cement to the inside wall of one end of the PVC pipe coupler and slide it over the other half of the pipe.
4. Apply PVC cement to the inside wall of the other PVC pipe cap and insert the remaining cut piece of 2” OD pipe half way in (0.75”)
5. Apply PVC cement to the inside wall of the open end of the PVC pipe coupler and slide it over the other half of the pipe.

Now you should have a fully sealed cylinder, next you need to drill and tap the holes for the inlet nozzle, outlet nozzle, and the drain pet****.

1. On one end, drill two 7/16” diameter holes on the cylinder’s centerline. These holes should be separated by about 1.5”.
2. On the opposite end of the cylinder drill one 7/16” diameter hole directly in the center.
3. Using the 1/4” NPT 18 tap, tap threads in the three holes you just drilled.
4. Using compressed air, or your mouth, blow the inside of the cylinder clean.







Making the Condenser Tube
The condenser tube is fastened to one of the inlet nozzles (i.e., 3/8" x 1/4" Bronze Hose Barb Elbow)via 1/8“ NPT threads, these threads need to be tapped into the nozzle.

1. Drill (to enlarge) the threaded portion of the nozzle using the 11/32” drill bit. Do NOT drill all the way through, just the up to the elbow.
2. Using the 1/8” NPT 27 tap, tap threads in the now larger hole.
3. Wrap one end of the 1/8” x 4” NPT Threaded Pipe with thread sealing tape.
4. Screw it into the newly threaded hole and tighten with pliers
5. Drill a series of 1/8” holes completely through the pipe, down the length of the tube; separate each by about 0.75”, starting 0.75” from the bottom.
6. File off any burs on the newly drilled holes and blow clean.

Assembling the Parts

1. Apply thread sealing tape to the threads of the two nozzles and the drain pet****.
2. Screw the outlet nozzle into one of the two holes at the top of the cylinder. Tighten it, but be careful not to over tighten and strip the threads.
3. Slide the condenser pipe/nozzle assembly into the other hole at the top of the cylinder (the condenser pipe slides into the hole), and screw it in snug again being sure not to over tighten.
4. Mark this nozzle as being the input (i.e., connects to the valve cover) however you choose, but I etched an “I” on mine.
5. Screw the drain pet**** into the bottom hole and tighten.

[shines]

It looks rough w/o paint, but the semi-gloss black paint makes it look very nice. I'll post pictures of it painted soon, along with the mounting bracket construction.

[alybudhwani]

this is great! i might do this

[Li0nel1234]

Wow... any pics of how well it works?

[IOM Black Diamond]

[shines]

Originally Posted by Li0nel1234

Wow... any pics of how well it works?

I'll finish it tomorrow and bolt it on my car while I wait for the one I bought to arrive. Maybe I'll compare their performance.

[shines]

Originally Posted by alybudhwani

this is great! i might do this

if you think of a way to improve it, please share!

[shines]

Here it is painted, it looks much better.

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[mikeSS]

pretty cool

[Li0nel1234]

Nice!

Any pics of the results from this or with it installed?

[shines]

Here it is installed

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[Li0nel1234]

Looks nice! Great Job!

[SC2150]

Nice work! You have the correct principals so I expect it to work pretty decent. Go grab a clear glass inline fuel filter and instal it inline between the outlet and the intake manifold vacuum and see if any (or how much) is getting pulled through.

[2010SLVRBULIT]

good idea!