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Making an oil separator.


How well it works.

Testing is still in progress, more updates though.

I have to say with both the small and larger air compressor filters did not filter all of the oil, alot still got through.



2" PVC pipe, cut down to about a 5" to 6" lenght.

2" PVC cap.

Home Depot barcode number: 039923136886 - $0.63

2" PVC female drain plug.

Home Depot barcode number: 039923213563 - $1.45

2" PVC plug for above drain.

Home Depot barcode number: 039923138049 - $0.59

2 (3/8 x 1/4) barb fittings, can either be brass or nylon, straight or 90 elbow depending where you mount it.

2 or 3 plastic SOS pads ( I used one of the plastic shower scrubs, found 3 for $1 at the $1 store.

3/8 hose (I used about 5ft of heater hose from NAPA.



  1. First thing I did was a test fit of everything together.
  2. Next I drilled holes for the barb fittings. Using a 1/2" drill bit (drill slow and steady, you don't want to crack the PVC, I drilled a hole in the top of the basic cap. Since I used the nylon barb fittings and didn't have a tap for threads, I used brass barb fitting to make the threads. Then I installed the nylon fitting, to insure no air leaks I used black RTV sealant on the threads (all I had at the time).
  3. Then I drilled for the bottom barb fitting. I mounted it as low as possible and because of that I had to drill through both the PVC pipe and the female drain cap. I held off tapping and installed the barb at the bottom until I put everything together.
  4. Using RTV sealant again, I applied a decent amount around the top of the PVC pipe, about 1" then mounted the cap w/ barb fitting to it. Then I gently tapped it to make sure it was a tight fit. Wipe away any sealant that gets pushed out.
  5. Do the same thing for mounted the female drain cap on the bottom, take care make sure the 2 holes are lined up. Again wipe away any sealent that gets pushed out.
  6. I used the brass fitting again to make threads, then screwed in the other nylon barb fitting with JB Weld on the threads.

    So far it should look like this:

  7. Next up, since I didn't use SOS pads, I removed the string from the bath sponge and spread it out. Then slowly pushed it in through the bottom, so that it filled the whole tube but not tightly.
  8. Let it sit overnight to let the RTV and JB Weld dry.
  9. Screw in the bottom drain plug and you are ready to mount it. Before mounting I plugged up one for the barb fittings and blew compressed air into to double check for leaks.




I mounted mine on the firewall underneath battery. To do this I made a bracket using an exhaust clamp welded to a bent piece of metal, drilled 2 holes in the bracket and used self tapping screws to mount it to the frame.

Mounting it down there is required more hosing to run, but it's easy to get to and remove the drain plug for emptying and cleaning.