Any evidence on the back of the head? There is at least one banjo there that could weep. High pressure lines do not salways spray. Sometimes it takes high PSI to force small amounts through tiny holes and around corners after.

Could have Cory put on the catch can at the same time. :)

Which system is more important to use a catch can on? I've always read it's bad to use one can for both.

It's not terribly "bad" as long as the hose diameters are all proper... after all, both systems return to the intake right next to each other. As long as the line from the can back to the intake doesn't cause restriction that allows crank ventilation to circulate into the heads (or vise versa I guess) then one can should be fine.

Though ideally, you'd have two cans, one for the valve breathers, one for the crank/pcv, you can definitely get away with one well designed can. Look at the Grimmspeed AOS... it's basically a single can for both systems, it's just that the can is the driver's side valve cover. :lol:

But if you're going to install on just one system, I'd guess the crank case/pcv is the better system for you to catch. Simply because you're not seeing long sustained G's at the track, plus with some mileage on your motor, you're more likely to have piston blow-by that's pressurizing the case more than a fresher motor might. But it's really probably a toss up... the right answer is "which ever system is blowing more oil".

Here's a pic of my catch can I found on the internet. All hoses are large diameter (nearly the size of a garden hose). Thoughts?

I can't see how that would work worse than no catch-can. ;)

That looks good.

Large diameter should let you do both feeds without any real issues IMHO. The AOS combines all the feeds into one but has large about 3/8"ID hoses all around.

The other key is hose routing as I think we discussed in another thread. part of the reason the vents all go high up onto the intercooler is that it limits the liquid in the system. If you feed one of the vents right off the heads/block to the firewall, there is significantly less vertical "drain" opportunity in the hose especially if the hoses actually run downhill into the tank.

Well, the risk, as I understand it, is introducing pressures where they shouldn't go, but I really don't get it since I haven't seen one installed firsthand.

Regular silicone hoses are not oil resistant and will weep oil without leaking much boost if any. Flourosilicone is resistant to oil and is too-rarely used on IC couplers.

Any chance oil is leaking out of the silicone inlet to turbo junction?

You can combined the valve cover breather hoses with the crankcase breather hoses if it is done properly. The Crawford AOS and the GrimmSpeed AOS both do this. I've done a couple AOS prototypes that did this too and worked well.

How do they do it properly? Isn't it the way you install it or does it really have something to do with the can itself? Should I get another catch can or can the one AVO one pictured above be installed 100% safely if done right?

That's where the turbo inlet hits the turbo right? I looked at it and checked the clamp for tightness. I'll double check it.

You guys just upgraded the turbo inlet to a Perrin for me last year.

Here are the directions for the Crawford AOS install...ignore the part about the coolant line. The Crawford can had a section that runs coolant thru the can to get the oil hot so you don't get that milky build up from oil that contains moisture.

http://www.crawfordperformance.com/d..._Version_2.pdf

If I was going to follow a DIY, it doesn't get any easier than . That's even near where I'd put the can since I have a small battery. The problem is that I don't know which line goes to the bottom nipple of my can and I don't know if these "approved" 1-can solutions are somehow better than my AVO can.

Almost every Subaru with a aftermarket hard turbo inlet (APS, Agency Power, AMR) has the crankcase and valve cover breather hoses tee'd together into one hose going to the inlet. One catch can on that one hose works fine.

that AVO catch can looks like it was designed to have multiple inputs though, so I would go ahead and use them. I bet there are pdf instructions online somewhere for it.

High on the firewall is better for a catch can than at battery level IMHO. The AOS doesn't care since the oil dumps back into the sump, but in theory you want as much oil that collects in the hose to drain back where it came, not into the can.

The single line (vertically) on the AOS returns to the intake.

If you think about it, there should be no pressure differential anywhere inside between the block or heads since they are all connected by huge oil galleys that flow way more than any hose could. My belief is that the majority of the people with catch cans that filled up where not due to the alleged pressure issues, but bad downhill hose routing to low mounted cans.

I did not know that. Interesting. I guess like silicone caulk/RTV, only some are oil resistant while others are not.

I think the problem was more an issue of hose diameter allowing the heads to effectively become the path of least resistance for crank pressure. So you would get a ton of flow from the crank into the heads and out the breathers that pick up a bunch of extra oil. If the crank breather is big enough, blow-by pressure can go out the top of the case instead of pushing out the heads.

At least that's my theory... after 10 years of farting around with this stuff, I still don't claim to really know how it all works.

I don't know either, but I do know that $4!+ rolls downhill, so anything you can do to make that towards the block rather than the can can't hurt. :)

And a bigger hose has just got to be a good thing. ;) TWSS implied.

That's the confusing part... I think if you use a big of a hose on the valve breathers (relative to the crank breather), then they become the path of least resistance for the crank-case pressure. At least that's what Warfield (I think it was a conversation with him that I had) was explaining to me.

I just used a craftsman garden hose when I ran my catch can.

I think I'll get a 2nd can at some point, once the current issue is gone (don't want to band-aid it or cloud the issue) and install two. The extra nipple on the AVO in conjunction with the drain plug can be used for a site tube.

Cory swapped the turbo on Thursday. The nuts that hold the DP to the turbo were pretty loose so maybe it was an intermittent internal turbo oil seal leak causing the oil smoke to simultaneously come from the turbo and the tailpipe. Cory couldn't identify any clear cause. Hopefully the issue doesn't return but if it does, Matt suggests a leakdown test to see if the motor is to blame.

Anyone know where I can find plastic nipples? :eek: I want to replace the plug with a nipple so I can add a site tube.

Summit
Assuming hose barb to pipe thread. Change as needed.

http://www.summitracing.com/search/?...b%20pipe&dds=1