DIY oil catch can for the backyard mechanic!

[festyfreak39]

Hello all

so for some of you that dont know what a catch can is, a vauge explination of one is: a metal cylinder/box with a breather that collects oil vapours/blow by from your engine

oil catch cans can be bought on ebay for 20 bucks plus shipping etc etc. this is the one i bulit for free with spare parts i had lying around... but one could make one for less then 4 bucks with some time and patients.

This also isnt a step by step DIY document, this is just to show that instead of buying one for 30 - 40 bucks, you can bulid one for 4 and put that extra money in your pocket.


Soooooo you need to start with some kind of metal container, and it just so happens my mom left her staples water bottle at home today!!!


Next you need a couple of these buggers..... you can find them at your local home depot but i had these laying around. Depending on your setup i only needed 2


Also you will need some hose clamps... i had these laying around too:


Next take the cylinderical object and drill 2 holes in it where you desire. the top one i used as a vent and i attached a APC breather thing which you can buy at any one of your local rice rocket stores, or at part source (but they are expensive there). You could also attatch an old PCV valve to it if you want to save some cash:


Use some teflon tape and start slowly screwing them into your catch can. This can be a pain but with patience it can be done, then mount it to your car:


Now this is how i routed my catch can, this is just the way i did it depending on your engine/application, you may want to do it differently but TADAAAAAA!!!!!!



this cost me 0 dollars, i will probably have to replace my moms water bottle..

**** disclaimer

DO NOT USE YOUR GF'S, WIFE'S, OR SISTERS LULU LEMON METAL WATER BOTTLE!!! THEY ARE 30 BUCKS CAD AND ARE EXPENSIVE TO REPLACE!!!!

[festyfreak39]

and i put it into the wrong forum... my bad, could someone move this to custom engine and drivetrain?

[Kraig]

Isn't air going to be pulled straight through your catch can, under the valve cover, into the PVC valve several inches away, into your intake, basically creating a vacuum leak? The PVC system is supposed to be a "closed" system. Does you car run ok after this mod?

[festyfreak39]

^^ car runs beautifully.

[ericsmith32]

Uhh isn't that backwards? Shouldn't it be connected to the pcv system? Should be able to use the same bottle easily.

[perucho]

It should be connected between the pcv and intake manifold.

[festyfreak39]

okay now this is gettting confusing...


the other line i can connect to the catch can is my PCV valve, all i have to do is drill it out and run a line direclty from the pcv valve to the catch can... (which im debating on doing) im going to say about 98% of the crankcase pressure is going into my catch can now though.

this has nothing to do with a vaccum leak and the pcv system is only closed for "emissions" stuff.

[perucho]

For your setup you would be better off running a long tube/hose under the car from the valve cover to the back of the car. The air flowing under the car would have some scavenging effect at the end of the hose, and help remove the vapors/oil from the VC.

[GenevaDirt]

im going to say about 98% of the crankcase pressure is going into my catch can now though.

this has nothing to do with a vaccum leak and the pcv system is only closed for "emissions" stuff.

There is nothing going INTO that catch can.....it has a breather on top and a connection into the valve cover....air is coming into the top of your can and INTO the valve cover. The line from manifold is sucking air through the pcv and that in turn is drawing air straight through your can. No way for oil to go into it.

[ericsmith32]

If you close up the pcv system you'll probably blow out seals. If you run a hose from the pcv to the connection on the side and the top connection should go into the intake manifold. That way when the air goes through the bottle it will fall to the bottom versus continuing down the hose to the intake manifold.

[blkfordsedan]

Actually, all he needs to do is plug the port on the intake and the end of the PCV valve with rubber vacuum caps and throw the hose away. Right now, he has a vacuum leak. HOWEVER, if his car has as severe blow-by as mine does, the mild vacuum pulling through the PCV valve is non-existent; completely overpowered by positive pressure in the crank case (even at idle). On a normal engine in decent mechanical condition, you would indeed install the catch can between the PCV valve and intake manifold port.

I have a catch can installed exactly like he does, except I plugged the PCV valve. I vent the can to atmosphere by letting a hose hang down under the car. Basically, its just like cars in the '60s used to be with a breather on the valve cover. It does work very well. The pressure blows into the can and swirls around. Any oil vapor collects on the sides and the remaining gases are vented out. My can will collect about 750mL of oil in a 100 mile trip at highway speed. The quality of the idle and the MPG actually improved when I installed it, just because it wasn't sucking all the nasty crap into the intake.

[sasquatch]

ya i have to get my VC vented... i put a 1/8th inch npt plug in the manifold where the hose would go... im gonna get some AN fittings welded to the VC and have a nice catch can somewhere.... im thinking about putting it in the fender so its hidden 8)

[blkfordsedan]

ya i have to get my VC vented... i put a 1/8th inch npt plug in the manifold where the hose would go... im gonna get some AN fittings welded to the VC and have a nice catch can somewhere.... im thinking about putting it in the fender so its hidden 8)

When I first installed my catch can, I stuck the vent hose into the inner fender well on the passenger side. I found out the cowl and inner fender are connected somehow, cause when I turned on the fresh air vent the whole interior filled with white smoke/steam. Now the hose just hangs down and blows on the steering rack.

[sasquatch]

my bp that i have has like NO blow by.... its shocking how good it is i can put my finger over or near the vent that goes to the intake and i feel ZERO air... and even if i take my oil cap off there is still no air comming out.... i can slightly feel the pulses that the motor makes cause its running but other than that it has 0 blow by... im happy about that but who knows what will happen when i add boost :p i think ill put the tank down in the front bumper in the wheel well on the passenger side... there is alot of space there... but that may be where i stick the water meth pump... maybe both... who knows

[festyfreak39]

Vaccum gauge installed already, no change in vacum the way i have my intake/catch can routed vs stock with stock plastic intake box.

and to what ericsmith said: The oil does not seperate from the vapour itself that easily, unfortunatly. the whole point of the catch can is so that those vapours do NOT go into your intake, if i would attatch the catch can back to the intake manifold, that would defeat the entire purpose. especially when im going turbo i dont want that oil in there.

the next step im going to do is drill out the PCV and install it into my catch can just like the other hose, and plug off the intake port where the PCV valve hose goes into..

This is how it was done on my miata when it was boosted, and now that it is right now as im bolting the supercharger.

and after a nice highway trip today withOUT the pcv valve hooked up to my catch can as well i can confirm the walls of my catch can are lined with a very small amount of oil that was not there before.

im just doing it the way all the miataturbo guys do it, and it has worked so far for me on my firefly turbo, miata, and swift.