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My DIY "Easy Drain" Catch Can

10K views 14 replies 8 participants last post by  08blackrt 
#1 · (Edited)
I put this together to use on my Kenne Bell supercharger PCV system. I imagine it could be used on any other car or set-up as long as it has room to mount the can high enough.

A little background:
I installed my Kenne Bell supercharger four years ago. The system comes with an oil separator. Since everyone knows them as catch cans, I’ll call it that from here on. I tested and discovered that the KB catch can lets a lot of oil vapor pass right through it. In a supercharged set-up, we try to keep any PCV oil vapor from being ingested back into the intake tract.

My thread showing just how much oil the KB catch can allows to pass through it can be read here: http://www.challengertalk.com/forum...or-lets-lot-oil-pass-straight-through-328474/

I put a second catch can in-line with the KB catch can. It is mounted “after” the KB unit. I chose the Arrington catch can because I like that it has a very small air filter inside it. It has the typical metal mesh material, and after that, all the oil vapor passes through the small, K&N style air filter. Any oil collected by the air filter drains back into the collection cup. I believe the air filter is the key component of this unit because the oil vapor is made-up of very tiny droplets, and this air filter’s passages are small enough to collect a lot of these droplets.

The Arrington can (mounted after the KB can) collects a lot of oil. I’m thinking there’s something about the KB’s PCV system plumbing that makes it move/pull a lot more airflow through the PVC system than a typical stock system. I say that because the Arrington can holds about 3.5 ounces, and I fill that up in about 200 miles.

The collection cup of the Arrington can is metal so I can’t see when it’s full, or close to full. And with needing to empty it every 150-200 miles, that’s a lot of unscrewing, empty it, wipe the threads clean, screw it back on; especially on an (almost) daily driver. Not a big deal at all. But, I’m a tinkerer. So I wanted a better way, and here is what I did.

Now, I can pop the hood, glance at my catch can, and easily tell how full it is.
If I need to drain it: I open the valve, the oil drains into my oil dipstick tube (back into the oil pan), I close the valve, and I’m done. Now, it takes about 5 seconds to empty my catch can.










The inside of the Arrington can has a 3/8” NPT female thread hole on the bottom, in the center. I bought an ESCO Sight Glass, 3 oz, P/N OSG3X375. It has 3/8” NPT threads on one side and 1/4” NPT threads on the other.




The valve I used is an American Valve M100 Ball Valve. It is rated for Oil/Water/Gas (OWG), and can easily handle the temperature of the engine compartment (temperature chart is on their website). I ordered it from American Valve. I cut some of the end off the handle so it fits better, and doesn’t stick out like a sore thumb. Then, I put the blue rubber sleeve back on it. The fittings are: A 1/4” NPT Street Elbow, an extension nipple, and a 1/4” NPT to 5/16” ID hose barb: All from the local hardware store. The hose is 5/16” Fuel/PCV hose from NAPA.




I never modify any original parts off my cars. I buy new ones from the dealer, modify them, and put my original parts away in case I ever want to put the car back to completely stock. That’s just me.

So, I ordered a new oil dipstick tube from the dealer ($19). He told me the diptubes have been revised and that I would need to get the new dipstick to match it (another $19). And, he was right. My original dipstick will not fit in the new diptube.

I installed the new diptube on the car to make sure I could get the old one out, and the new one in. It was tight because of a mounting bracket underneath, and a bit of a challenge, but I got it out (and in). I marked exactly where I wanted my drain connection to be, and pulled the diptube back out.

I bought a short piece of 5/16” brake line from NAPA. It was cheap, and would work. I cut the ends off it (one at the angle I wanted), drilled a hole in the new diptube, mocked it up, and took it to a friend for him to weld it in place. Then, I brought it home, cleaned the inside, painted the welded area, cut the brake line to the length I wanted, installed the diptube, and the hose.






It works like a dream!

My original intention was to install a solenoid valve instead of the manual ball valve. That would give me an automatic, self-draining catch can. It would be a Normally Open (N.0.) solenoid connected to ignition 12 volts. When the car is turned on, the solenoid would instantly close, seal-off the drain hose, and stay closed as long as the engine is running. When the car is turned off, the solenoid would de-energize, open, and allow the collected oil to drain. This would happen automatically, every time you turn the car off. I searched for years for the right solenoid to do this. It has to be rock solid reliable, be rated for OWG, and be able to handle the environment of the engine compartment: Vibration, water (rain), and temperature. I found a solenoid that meets all my specs except for one. The temperature rating of the body of the valve is fine; however, the temperature rating of the electrical solenoid is very close. I am 99% sure it would work fine, but am still searching for one that gives me full confidence.

For anyone who is thinking, “You put catch can oil back in your oil pan?!?!” Yes. I do. As the rotating mass of the engine is turning, oil is being bounced and thrown all around the crankcase. That crashing oil is what is being turned into oil vapor. As the PCV system flushes out the crankcase combustion gasses with fresh air, that airflow coming out of the crankcase, heading to the PCV Valve (and your catch can), is full of oil vapor. When you turn the engine off, all of the oil vapor that is still inside the crankcase settles out and falls back into the oil pan (to be used again). The oil in the catch can is exactly the same as the rest of the oil in the oil pan. A few people have sent oil from their catch can, and oil from their oil pan, off for a detailed oil analysis. All the results report that the oil in the catch can has the exact same properties, gasses, and ingredients, as the oil in the oil pan. There is nothing “extra,” or harmful, in the catch can oil.

I put a small nipple inside the top of the sight glass fitting. If I didn’t do this, the oil from the top of the catch can would drip into the brass fitting, wick its way along the side of it, wick its way along the roof of the sight glass, and down the wall. This nipple makes the oil drip directly into the sight glass, and stops it from wicking along the roof of the sight glass. It just keeps the roof and upper walls of the sight glass from getting oily. It keeps it looking “cleaner.” The nipple I used is a nylon “T” hose barb. I cut one end off and forced it into the nipple. It’s a very snug fit.





Other photos:


 
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#2 ·
You did some nice mods to the catch can. However, there is one major problem. Under no circumstances should the captured fluid in the catch be re-routed back into your oil pan. If you do, you are degrading your oil by mixing it with a nasty brew of condensed oil, fuel, water vapor and other contaminants. (Did you ever smell the fluid in a catch can? It smells more like gasoline than oil.)

Read this explanation from Bob the Oil Guy:

"During normal operation of an internal combustion engine, there’s a compressed air and fuel mixture inside the combustion chamber that is ignited and as a result, forces the piston down. A small amount of that ignited mixture leaks past the piston rings and ends up in the crankcase. This leakage is often referred to as “blow-by” (leakage past the piston rings), as well as oil mist. Some of the oil mist and other products settle along the engine intake and over time form a “gunk.” The oil catch can collects the oil mist and condenses the fuel vapors while allowing “cleaner” gases to be passed back into the intake. Typically the blow-by gasses are passed through a wire mesh, which give the vapor droplets something to adhere to. Since the oil catch cans condense the vapor portion of the gasses, they will need to be drained periodically of all the oil, fuel and other contaminants.

In addition to the air/fuel mixture and oil mist, there’s also the possibility of condensation, or water droplets. Condensation is more susceptible in humid climates, but it can exist anywhere there is fluctuation in temperatures in a hot to cold environment."
 
#8 ·
I still woudl not re-cir that catch can fluid into the engine oil, I have often emptyed a frothy mixture of oil and condensed water out of the catch can, and usually it is quite fuel contaminated. I will admit that this was not on a challenger but shoudl be pretty universal. Aersolized oil picks up all sorts of combustion remnants, some unburnt fuel, and when re introduced to the engine oil can hurt viscosity and shear strength of oil, especially on a performance car that has been tuned a tad rich for a saftey margin at WOT.
 
#9 ·
If it is the same oil why catch it then? Just let it vent back through the intake and get burnt up in combustion... Extra lube for the valves...lol..

Not me.. I would not do it.. A motor will sweat new old or other. There will be condensation somewhere..
 
#11 ·
If it is the same oil why catch it then? Just let it vent back through the intake and get burnt up in combustion... Extra lube for the valves...lol..
Oil does not burn at the same octane rating as gasoline does. Oil in the fuel mixture inhibits the combustion process. It causes knock/detonation, which is bad for a blown motor.
 
#12 ·
I recently posted a thread reguarding my oil blow by on my KB setup as well. I am to the culprit of empting back into the crank case. My car allows so uch blow by that I would need to add a quart every few hundred miles if I simply disposed of the blow by. LOL I simply empty my can back into the crankcase. If I could now determine why so much drains from the line to my intake tube I would be a happy man. I think I am going to install a cheap catch can inline with that drain tube to see if that helps. Great write up I might need to modify my current setup.
 

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#13 · (Edited)
Hi Teddy,

I thought I was getting oil vapor coming in through my intake tube also. So, I installed a catch can on the fresh-air side also. Here is my thread: http://www.challengertalk.com/forum...ator-install-kenne-bell-fresh-air-side-84283/

However, that catch can has remained completely dry. I know some oil is still getting into the back of my blower, but it's not coming through the throttle body. It is oil vapor that is still making its way through both of my catch cans on the PCV valve side! I wish I had room to mount another one on the PCV side.
 
#14 ·
After looking at all your pictures: Just a thought . . . Its looks like your PCV hoses go downhill and then back uphill. If that's true, the hoses might be filling up with oil, that oil can't drain because of the downward loop in the hoses, and not much air is flowing through them because the hoses are mostly block-off by the standing oil. That could mean that you have some blow-by oil vapor going out the fresh-air side all the time the motor is on, instead of it going through the PCV Valve as it should.
 
#15 ·
I wouldn't put it back in just because there's so much fuel in it. Just smelling mine when I empty it is enough to tell me it's got a good load of fuel in it. I took and put it into a clear bottle and let it sit and it seperates into 3 or 4 layers after a week or so.
 
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