Catch Cans

I thought I would post this as I have read tons of questionable information regarding catch cans on variois forums...and the Superbowl is a snoozer currently. They are quite easy to set up and clean if you get a can intended for the purpose and don't try and cheap out on some eBay special or build your own. I was reading a mustang forum post earlier and was surprised how many people were saying an air compressor air oil seperator from harbor frieght was just as good as the over priced catch cans being sold. Many people try and go this route only to get frustrated that they are too small and a PITA to service. These are not intended to be easy to service as they are for applications with long service intervals. There are tons of DIY catch can threads and I don't recommend going that route.

Pony up for a good one and you'll see why they are so expensive. These are not just cans. They are usually constructed out of heafty billet Al and well engineered with specific mountms and fittings for the car and purpose. When I got my APR can I was a little miffed at the price. Once I got it I was impressed and felt this thing will outlast the car, and the next one, and the four after that. If price is a concern try and find a used one but even used they are still pricey. Cheap out and you've just made the good one more expensive when you scrap the cheap POS and buy a good one.

For my setup a catch can is a must. If you're still running the stock PCV than the need is up to you, but if you ever had
the P0106 code pop up again and again you'll probably agree it's nice to have.

Placement

Place it somewhere easy to access. For me right up front using one of the headlight bolts to secure the mount.



Takes literally 15 seconds to remove 2 hose fittings and 1 bolt.

Media

Make sure the media is easy to clean. I prefer baffles over steel wool type media. And this is why...



That is totally normal. Remember a catch can separate air/oil/water leaving oil/water behind in the catch can. That cheese is what you get when oil absorbs moisture. If you ever see that under your oil cap that is not a good sign.

Service

Pick a can that is easy to service or you'll hate it.

For mine it's only 5 bolts. Maybe a minute to open.



Pull the media.



Clean the media and can. Maybe 5 minutes.



Put it back in the car.



And you're done. Simple.

Vented vs Sealed

Choosing vented or sealed is up to you but if you're running the can back to the intake it can't be vented or it's just a big vacuum leak. I say get a non-vented can then you can use it for both use cases. Just put a filter on the output side of the can. If it's a vented can there is only one input and can't be used for a vacuum setup.

Botton Drain

A nice to have but you'll still need to open it to clean the media so IMO it is not really necessary and not something I would base a purchase decision on.

Bottom line is if you want a catch can buy a good one that is intended for your purpose and set it up right with serviceability in mind and you'll be stoked you have it.

...a side note on freezing

There are considerations for the can in winter so the water in the can doesn't freeze but I live in California at the beach so I don't know much about this subject.

...and someone finally scores with 7 minutes left in the 4th. About time.

WW, I know a few guys running catch can but none having as much "cheese" on the baffles as you have, hopefully those pics are old.

Nope. Just took them yesterday. The cheese is simply oil/water. Without running a PCV and having a large diameter hose (-12AN) you get a lot of vapor coming through. The main reason for so much oil is I am in a lot of stop and go traffic so I am at idle a lot. Normally the PCV would be closed at this stage. With no PCV you are running air through the can all the time and at idle there is less flow through the can, as I am plumbed back into the intake/air filter side of the throttle body, so more oil gets deposited. When I had the PCV I hardly got any cheese. Also, when I do long freeway trips I get almost no cheese as well. Another factor is low vacuum. Vacuum helps the rings seal so I get more blowby from that. Finally, the valve cover also plays a role. Where the vent/baffle sits in the cover is a major contributing factor in how much oil gets pulled out of the valve cover. There is definitely a reason the PCV sits on that big ass plastic tower on the stock valve cover and if you look at the bottom of the stock cover that tower is pretty well covered up...and you still get oil coming through the PCV. Compare the outlet placement of the stock cover vs the IE cover and that is the biggest reason for oil getting pulled out and why I couldn't use an aftermarket PCV to alleviate the issue. There is pretty much a 3/4" hole sitting right (maybe an inch) above the valve train. Plus the 90k miles on the odometer doesn't help. This is totally normal for my setup. I have removed the valve cover and looked at the inlet hose to the catch can and there is zero cheese anywhere but the can. If you look at the first pic in the thread you can see the inside the inlet and outet fittings when I am removing the can are clean. It's simply a byproduct of pulling a lot of oil out of the valve cover.

On another note. Google "Catch Can Sludge" and you will see tons of threads of people freaking out and all sorts of theories. One big misconception is the catch can keeps this sludge out of your engine. Wrong. The sludge in the catch can forms because of the catch can, IE no catch can no sludge. If you didn't have a catch can the ingredients that make up this sludge, namely water and oil, get sucked into the intake and burned up in the combustion chamber. What you will likely see is oil in the intake, which you no doubt see in a stock setup as well and the water will evaporate or get burned off. There are times you will see sludge like that under your oil cap. This is usually the case for people who live in cold climates who make short trips in winter. When you make frequent short trips in wintertime the car doesn't run long enough to burn off the crankcase moisture and the oil absorbs the moisture forming that sludge. This is not good but is usually rectified by driving the car longer distances. A blown head gasket can also do it as well I believe.


Not my car. Just a pic from the web.

I think the worry is that what's in the catch can is coming from the valve cover. Not usually. It is simply the conditions that cause the above to happening are happening in the catch can which makes sense as the catch can collects water and oil and never gets very warm.

This is pretty old but I'm in the process of trying to solve my pcv routing dilemma after installed my IE manifold. 09mk5 2.5
Would it be more beneficial to run a one way vent to atmosphere catch can or a traditional two hose catch can from pcv to intake?. BFI makes a catch can with one hose from PCV to the can. No outlet hose. Just a mini filter. I want to run somthing like this but I dont want to rob any power or cause pressure issues.

Vwz0mby said:

This is pretty old but I'm in the process of trying to solve my pcv routing dilemma after installed my IE manifold. 09mk5 2.5
Would it be more beneficial to run a one way vent to atmosphere catch can or a traditional two hose catch can from pcv to intake?. BFI makes a catch can with one hose from PCV to the can. No outlet hose. Just a mini filter. I want to run somthing like this but I dont want to rob any power or cause pressure issues.

Click to expand...

Sorry for the delayed reply. I don't get notifications. The vent to atmosphere is a mess and that little filter gets clogged up pretty fast and blows oil everwhere. Also you can just pop a filter on the barb end of a closed can with in/out hoses so it can be used in both ways whereas a vent to atm only can will always be a vent to atmoshere can only. In my experience the best bet is to vent the can to the low pressure side of the intake (ie to the intake before the throttle body by the air filter). This is clean, environmenatally friendlier and flows better without the oil loss from venting to high vacuum at the manafold.

WW is the expert on this, he went through all the catch can options for the 2.5.