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Discussion Starter · #21 ·
Okay, in retrospect this was a poor design. I had the right idea with the brass fittings and heater hose but the jar was too small, the o-ring was very soft and broke and it was too thin of a material for threading the fittings into. I don't know what kind of metal this is...The kind of "made in China" chrome-copper look as it's rubbed off a little.

Anyways, I still have it in my jeep. It was mounted horizontally and I used a small diff. breather filter you can get at Auto Zone down the rice isle facing vertically. Either the size of the can, but probably because it wasn't mounted right, made it work horribly, spraying oil over the motor. It's not that bad and I suppose it's worse than oil in my air filter.

I really think if you're on a "budget", you're better off using an old coffee can or an oil bottle like PeteYJTJ mentioned.

3 Posts
Why do you say it was to small, are you referring to the air volume capacity inside of it? Sorry for the dumb question...

I got a vacume canister from a break system. Thougth about using that...

2 Posts
Hey guys

So I've always had a bit of oil leaking out the PCV system into the air filter, but not enough to warrant making a project out of it. The intake of my YJ was replaced by the previous owner and upgraded to a Power Adder intake, which is very similar to most K&N performance intakes, without the enclosure.

Now because there is no enclosure, the platform the stock air box mounted on was left open. I installed a $30 Fiamm air horn kit where it used to be, but part of the tubing was melted apart by a mysterious heat source. Now, I used to have the same air horns mounted on opposite side of the engine bay, but only failed to work when water rusted the horns themselves out (see: mount with bells facing down...). So I believe the culprit to be hot oil coming from the crankcase. In order to remedy this, I decided to make an oil catcher. I have seen them advertised online, but the only ones I could find were very expensive.

From what I have read, oil leaking out of the valve cover, through the PCV hoses and into your air filter is caused by excessive blow-by. Blow-by is when you lose compression due to a poor seal between the piston rings and the cylinder walls.

Because new rings, or an engine rebuild is way out of my budget, I decided to create a very cheap and simple way to keep oil from reaching my air filter.


-1 jar. Threaded is probably the easiest and secure type, but there's a world of parts out there. The jar I bought is made from some type of metal, It's not steel, probably some cheap aluminum alloy. The jar I bought is a "Monster Pill Fob", marketed by some unknown company. They have them at my hardware store along with the other doo-dads on the counter. I have been thinking about this project for a while and the monster pill fob things have seemed like the only viable, metal jar I can find. I figure this jar is about 2-3 fluid ounces and shouldn't need to be emptied that often.

2- Stainless hose clamps. The width of your PCV hoses may be different than mine, so measure and buy accordingly. I used SS because it's one less thing to rust in New England winters.

2- Barbed hose fittings. I bought a straight and a 90* fitting, but I would recomend getting fittings that work with how you want to mount your oil catcher. If it's going to be below the level of the hose, then two straight fittings will probably work best. If it's going to be floating, or on the same plane as the PCV hose, then two 90* fittings would work best. I bought a straight and a 90* because they ran out of stright fittings. While the straight fittings only cost about $2.50, the 90* fittings cost about $6, and I couldn't afford two 90* fittings. The ones I bought were 3/8" OD, with 1/4 NPT (National Pipe Thread) threads. Buy fittings that properly accommodate your PCV hoses.

All together, my total came to just over $19.00, so this is something most people can afford to make, provided you have access to a small variety of tools:

Jar- $8.00
Clamps- $1.29/piece
Straight fitting- $2.50
90* fitting- $6.00

For tools, you're going to need:
-Tap, appropriate for thread pitch of fittings
-Tap handle (I used a pair of Vice Grips)
-Drill bit, appropriate for size of tap
-Center punch (I used a small tap)
-Cutting oil (for cutting threads)
-Screwdriver (for hose clamps)
-Drill press or power drill
-Bench vice

Most of these tools are household items. A tap usually costs between $5-$10, and the drill bit is about the same due to it's large size.

The first thing I did was to remove the small nub from the top. I used some masking tape around the top to protect the finish. I recommend using stronger tape like electrical or duct, as my saw scraped away some of the tape and marred the finish:

After that, mark, punch, drill, and tap the first hole:

Now keep in mind, these are plumbing fittings that are threaded for NPT (National Pipe Thread), which taper out as you continue to cut the threads. In other words, the more of the tap you use, the wide the hole is going to get. So, every couple turns as you're cutting your threads, remove the tap and see how your fittings fit. Once they feel snug around the top of the threads, that's as far as you need to cut.

Both holes, drilled and tapped:

I have to say, the metal that the jar was made out of was very thin. If you use a similar type jar, be careful to start the threads straight because you could widen the hole past the point of threading.

Here is the lid with both fittings installed:

The underside of the lid, with the barb fittings installed:

And the complete project:

I sealed the threads with blue loctite, however I'm sure Teflon tape or nail polish will work fine as well.

After it's finished, you just need to cut the hose and clamp them to the fittings once you're jar is installed in your Jeep.

Since I messed up the shiny finished, I decided to paint the very top of the jar, but left the bottom it's chrome/silvery finish. I'll have some pictures up as soon as I have it installed.

All together, this was a very quick, easy, and cheap project that most people are capable of and can help prevent oil from reaching your air filter.

Let me know what you guys think!

Hey, I know this is an old post but can you post photos again. Nothing is showing. Thanks much!

Think Outside the Catalog
9,731 Posts
Hey, I know this is an old post but can you post photos again. Nothing is showing. Thanks much!
I doubt it. This is a really old thread and the original poster has not signed in since 2013.
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