Building a oil catch can and its purpose?

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Sep 13, 2004
walnut, Ca
First, I drive a stock slow honda that sees its share of abuse. (auto-x, caynon driving) a couple times a year. Recently, I've seen a lot more people using oil catch cans (homemade or bought.) I was going to just run a longer pipe from the pvc valve on the crackcase to a small metal container, stuffed with steel wool with a pvc breather on top of it to release gas when needed. Is this overkill, or is it a valid concern? (the need for a oil catch can) It seems like with any of these additional add ons that dont come from the factory on modern cars, its overkill. thoughts? This was posted early this week, but deleted for some reason. Thanks!
A catch can may fall in the same category as an oil drain plug magnet. The information you get from either one is probably more valuable than what they do unless you have a real problem. Then it's a bit late.
It's only worth it, imo, if it keeps oil out of somewhere that it's bothering you. Examples are throttle bodies and intercoolers that fill with crud. A catch can won't keep you from burning oil and by definition restricts your PCV system at least slightly which will degrade your oil. Incidentally I think they're usually plumbed into the fresh air intake hose, not the PCV hose. What goes through the PCV valve usually gets combusted quite handily. The fresh air vent hose on some models poisons the paper air filter with oil and is upstream of the throttle blade on practically all vechicles. The only time oil gets spewed through these is at WOT; the rest of the time there should be a vacuum present. Keeping the oil fumes under control at WOT might help if you're getting detonation.
Originally posted by Ankur: I think i understand what you are saying. So is it worth it to build it?
Depends. If you want to learn what's in you PCV valve flow, then it is. If you are only interested in results, then you won't know until you intall one and observe the results.
I'm also interested in fabricating a catch can for my PCV system. It would attenuate the wet deposits left in the intake manifold runners, where the hot gas condenses and leaves a residual mess. I heard of good results with a water/oil separator used for air compressor lines, put inline from the PCV to the manifold. I'd get the biggest one I could find, though.
Originally posted by Ankur: [QB]Is this overkill, or is it a valid concern? (the need for a oil catch can)QB]
IMHO, it depends on the application. Some engines seem to blow out more of an oil mist than others. In a stock setup, this mist will go back into the engine via the air intake. This isn't a place you want a large amount of oil to be. For example, this was a big problem with Harley Davidson engines during the mid-eighties to late ninties.
ok, this is my temporary solution. If it catches anything, I will make something more concrete. haha  -
yup palut, you have the same car as well right? Its a 94 accord. The breather on top is just a fuel filter. I'll give you guys a update in a couple weeks if the catch can actually has any deposits in it. btw, this is what I used on this ghetto version. -1 steel "JDM" beer can -steel wool -2 feet automotive pipe -pet cock (sp?) -fuel filter on top, pvc breather can also be used.
That is GHETTO!! Too funny. I'll be rigging one for my beater turdbo soon. My crankcase breather feeds back right before the turdbo. So any crap gets on the 253,000 miles my car has some blow by - and some small oil consumption. Keeping this oil out will help IMHO. I'll just block the preturdbo hole and then route the pipe to my rigged can....It'd be cool to have a glass or plastic can to see the juices (if any)....but metal is probably smarter.
I went out to the garage to go hippieghetto and rig a qt. yoghurt container for a plastic oil catch can - but when I took the oil breather hose out of the hard tube before the turbo inlet, the breather hose was so clean and dry, I bagged the whole project. Sure some fumes must go through that hose but no oil, or condensating oil vapors.... So what IS the performance gain (if any)? Allowing the crankcase to freely vent? OR not having that intake vacuum sucking on the crankcase? [I dont know]
I dont know pablo, we will see if my NA engine benefits at all from this. I have 190k, so its a lot of mileage as well. I think in your case, having this would prevent the turbo getting a huge dose of unwanted oil?? My car has run the exactly same since I did this 3-4 days ago, so I dont think it hurts the engine at all. I used a vacuum plug on the intake, and so no leaks are apparent.
Originally posted by Pablo: So what IS the performance gain (if any)? Allowing the crankcase to freely vent? OR not having that intake vacuum sucking on the crankcase? [I dont know]
Honestly, I would assume there would be a very small performance loss. Most IC engines like a small amount of vacuum in the crankcase. There are check valves on the market that are designed to keep this neg pressure in check when performing mods to the crankcase vent system.
Doesn't a PCV valve need vacuum to work properly? That just looks like a really ghetto breather setup...
Well, I would rather see the normal PCV hose attached to the fuel filter there. If nothing is seen in it ..the larger can is containing the oil.
Gary, I'm a little confused. Are you saying the hose that is coming from the pvc valve should go straight into the fuel filter, which is attached to the can? As of right now, the hose is going into the back of the can, and the fuel filter is the breather. [ May 23, 2005, 02:45 PM: Message edited by: Ankur ]
Use the can as an intermediate chamber. Then there are no "mods" per se~ ..just a place for any unwanted material to step out. You still empty as needed. You have your draft for the internal vapors ..nothing should migrate out the "IN" plumbing. Essentially run a hose from the plugged port on the intake the fitting that you have swinging in the breeze there. It makes everything very (phonetic spelling for effect) Pretta Porte~ [Big Grin]
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