During March this year, I purchased an oil catch can through eBay and found out it was a little too big to easily fit in my car's engine bay, even though I looked for the smallest one listed.
I decided to make my own (smaller) oil catch can:
My custom homemade oil catch can consists of a small 125ml oil can with the brass pump and spouts removed from the screw top lid. The blue Faithful oil can cost me £4.08 from Aird & Co in Brighton.
To avoid butchering my car's PCV tube, I purchased a couple of spare PCV tubes with spring clips. Both were from 4th generation Honda Preludes, the first one cost me £3.50 (including P&P) sold by a Lude Behaviour member and the second was sourced from a local breakers yard for £1.00. One has been cut in half and the other is used in its entirety.
Inside the can, I have used 3.25 meters of zinc plated metal chain purchased from B&Q for £1.85 per meter. The chain acts as a filter to help catch the oil.
After drilling holes in the oil can lid for the fittings, to make it air tight, aluminium foil tape was used above and under the lid to cover the original holes originally occupied by the brass pump and spout. A thin metal disc with appropriately drilled holes was cut to size and placed on top to further help keep it air tight and to tidy it up cosmetically.
2 plastic pneumatic push fitting male elbows (1/8 BSP) were fitted to the oil can lid and they cost me £0.99 + £0.50 P&P through eBay. They are exactly the same diameter of the PCV tubes, so to join the tubes to the elbows, I have inserted 1" of a plastic tube (section of pen with the contents removed) in each elbow. The 2 elbows are secured in place with 2 pneumatic fittings (1/8 BSP) inside the oil can lid which cost me £2.40 + £0.60 P&P again through eBay.
To direct the oily vapour deep into the can and through the chain, I have fitted a 2" length of plastic tube (again, a section of pen with the contents removed) to one of the internal pneumatic fittings.
For cosmetic purposes and in a bid to help reflect heat away off the oil catch can, I have wrapped it in a layer of aluminium foil tape.
Here's a little bit of the theory behind the oil catch can, copied and pasted from my web site:
The oil catch can is a small container which is fitted along the rubber PCV (positive crankcase ventilation) tube which goes from the crank case / valve cover to the intake manifold. A minimal amount of combustion gases escape past the piston rings into the upper engine which are are mixed with the oily vapour in the engine then recycled back into the engine intake via the PCV tube. Over time, this oily vapour can coat the inside of the engine intake, which reduces performance and fuel economy. The oil catch can reduces this by helping to catch some of the oily vapour before it gets to the intake manifold, thus improving air flow. With an oil catch can fitted, the recycled gases going into the intake manifold from the engine are cleaner and carry less oil. Without oil in the air/fuel mixture, it is more combustible which increases power and fuel economy.
