Oil in the Intake?

[TouchStone]

Pulled the inter-cooler off and found a pool of oil inside the pipes. Is this amount normal for only having 100 miles?

https://farm1.staticflickr.com/689/22621572439_084b3f39e6_z.jpg (https://flic.kr/p/AsZtn2)

[redfogo]

Is this a new turbo and motor? Or used? Seems normal if its used.

[Hindsight]

Some amount is normal, yes. There is a shelf there where it will collect but tough to say how much is normal by looking at that. I would say its normal. That will reduce octane rating and intercooler efficiency though so consider getting an air oil separator, or a catch can.

[STiPWRD]

Normal, I've seen worse on a stock engine with no oil catch can/seperator.

[rjh2pd]

That is what mine had when it was rebuilt and had about 30k on it. I'm thinking about getting a catch can to prevent this.

[TouchStone]

The turbo is used but has been cleaned and a new chra installed.

Where does the oil come from, turbo or the engine vent? My guess is from the engine due to oil spray in the turbo. Where does the catch can get installed?

https://farm1.staticflickr.com/634/23086860831_7cc2130010.jpg (https://flic.kr/p/Bb7coF)

[metalmaker12]

Get the Crawford or Perrin catch can kit, only two proven to work correctly with a Subaru

[STiPWRD]

The turbo is used but has been cleaned and a new chra installed.

Where does the oil come from, turbo or the engine vent? My guess is from the engine due to oil spray in the turbo. Where does the catch can get installed?

https://farm1.staticflickr.com/634/23086860831_7cc2130010.jpg (https://flic.kr/p/Bb7coF)
Check out this:
http://forums.nasioc.com/forums/showthread.php?t=754710

There is a vent line coming from the top of the block and two coming from each head valve cover (that are T-ed into one hose). Both the block hose and heads hose run to the turbo inlet pipe where the oil vapors get sucked into your intake system. I installed two catch cans: one between the block and turbo inlet and one between the heads and turbo inlet. These are not name brand catch cans so we'll see what happens.

[ssssly]

Correct, all of the block and head vents are returned to the turbo inlet and that is where the oil in your intercooler is coming from.

If the turbo blew a seal you would have a blue fog blowing out the exhaust that you would definitely have noticed. As well as pooled oil in the muffler.

I myself have run the GS air oil separator on all my Subarus. It attaches to the oil filler neck to return the blow by to the oil pan.

Then on the line that runs from the AOS back to the turbo inlet, I run a standard air line AOS like you would find on an air compressor. Simply because I compulsively over-engineer things and they are compact and cheap.

[TouchStone]

This sounds like a serious issue to me. Why is an AOS not included stock, is this only a major issue for race applications? I'll be installing the Perrin AOS in the near future.

[Bob_n_Cincy]

This sounds like a serious issue to me. Why is an AOS not included stock, is this only a major issue for race applications? I'll be installing the Perrin AOS in the near future.

TouchStone
The Subaru does have an AOS built in.
It's under the flywheel.
47665

[ssssly]

There is an AOS for the bottom end as shown above, it is composed of a couple of angled steps to do some minor condensing before venting to the upper.

The top of the crankcase and both heads vent straight to the turbo inlet.

With the amount of oil I have seen dumped out of intercoolers from perfectly operating engines after a moderate to spirited track session, I would suggest some method of removing oil prior to returning crankcase and head air to the intake. Particularly if you plan on pushing the engine .

I have also seen cars that are almost always practically dry. So YMMV.

Can always throw a homemade catch can in there for a bit to see how much oil your engine likes to expectorate and go from there.

[Sgt.Gator]

The AOS question is one of the most hotly debated there is. There is a thread on NASIOC or IWSTI that runs 160 pages. I read the entire thing and concluded that half the people posting said they are great and half said the AOS caused their engine to blow up.

Here's my experience: My race car has no AOS. When I asked Cobb if I should put one on they advised not to for OEM shortblocks and tunes under 400 HP. In their opinion it was better to stay stock, so I did until I installed a Dry Sump which negates any need for an AOS. The engine ran great with negligible oil in the intake tract. Then last spring I blew the engine up. Not unexpected since it was the same engine since it was first raced in the 2006 Grand Am Cup.

I bought a Spec B with a built motor. Forged pistons- rods- FMIC- and a Crawford AOS. It drove great from SoCal to Bend and around town, although the 20g was bit too much for a daily driver IMHO. Then I took it to the track and spun a bearing in 20 minutes. When I pulled the engine I found the FMIC and the entire intake tract had a LOT of oil in it. The oil drained out of the FMIC standing on end for days. I'm not 100% certain why the AOS failed, but I did notice the drain back line had a bit of a kink in it that you could really not see under the intake manifold and hoses which is probably why it failed. I sold the Crawford AOS.

I have researched all the AOS's. So far I like the way the Perrin system is hooked up the best. However I'm not going to buy one for the Spec B until I see if my rebuilt engine is oiling the intake badly. And I'm convinced an 818R has to have a dry sump, so no AOS for that.

TouchStone, I wouldn't be concerned about that little bit. That's nothing like my Spec B!

[scott s]

Forged pistons due to the larger clearances needed are going to be more off an issue with blow by than stock pistons with correct clearances. Though the 4132 alloy forged (Cosworth and some others) I think its 4132 off the top of m head anyways lol have tighter tolerances than the forged I think it is 2618 or whatever because of different expansion rates as they heat up but the 4132 is claimed not as strong.
If you put a large turbo on I think a good aos is a needed item. IAG has some that are claimed to work real well and return the oil to the crankcase.
The cheap grimspeed was a known flop but I have not much on their new supposed version 2?? The original grimspeed just did not do the job on the track and was iffy on the street with spirited driving or so I have read.

[ssssly]

Is amazing how the blame for blown engines is always an AOS or some other bolt on and not the driver that pushed the engine beyond reasonable limits or installed a part they didn't know how to tune for.

I have read and contributed to that thread. And I never saw anything backed up, with anything that would be recognized as reliable data, pointing to an AOS causing an engine failure. Or a cogent explanation as to how it possibly could. Plenty of half baked theories, but not much I found to be grounded in reality.

Which of course says nothing about if they are generally beneficial of detrimental. Which would largely be dependent on the the amount of oil in the intake and if its effect on total octane is severe enough to create an unsafe timing/fueling situation.

As such I would tend to generally agree with your above statements, relayed from Perrin. On a stock engine/turbo/tune it probably provides little to no benefit or additional safety margin. Other than making you feel better about the world because there isn't any oil in your intercooler.

Where I would differ is on the characterization that a certain HP level would necessitate one. How close your timing/fueling curve is to the edge of detonation, at the octane of gas you are running, would be the real deciding factor to me.

Since the only real detriment to burning engine oil in the cylinder is decreased effective octane, if you aren't anywhere near detention with your current tune, wether you are burning small amounts of oil is largely irrelevant.

However, if you have a tune that is close to the edge of detonation, and that tune was done while the car was stationary on a dyno, and you then get it out on a track with the oil sloshing around, and increase the amount of oil blown into the intake vs when it was tuned, and that manages to decrease octane enough, you now have a problem.

Yes I realize the number of "ands" in that equation. Hence my self admitted over-engineering problem.

And yes, the amount of oil in the pictured intercooler is negligible.

[TouchStone]

@ssssly, I agree with your reasoning, it makes sense that conservative/stock tune/parts can handle burning some oil. While an aggressive tune would be more sensitive to it.

[Sgt.Gator]

Just to clarify, I wasn't blaming my blown Spec B forged motor on the Crawford AOS. It had a spun bearing, a highly unlikely event from a knock- detonation problem. I was explaining why I took the whole engine apart and what I found throughout the intake tract., lots of oil.

I think the 400 HP comes from the general rule of thumb that at 400 HP you should be running forged pistons and to get to 400 HP you will need a lot more turbo than stock, both of which compound the oil in the intake problem, therefor an AOS is recommended. .

[Pearldrummer7]

47719

On mobile, so excuse my lack of formatting.

That's a photo of my 818 intercooler after 3.5 track days with a V1 Crawford AOS. The silicone inlet looks the same (clean). My stage 2 WRX (DD) always has oil in the intercooler. The 818 is always bone dry. I will continue to run my AOS on it until I have issues, but I think it's a fine thing for a car seeing track duty.


That said, I have a detuned hybrid build with forged internals.

[Legacygt21]

Touchstone,

Its possible you have a bad / gunked up PCV. So it doesn't close all the way under boost allowing the crank case to become over pressurized thus pushing more oil into the inlet of the turbo. Like others have said a good AOS will likely fix your issues. I personally run the Carwford AOS on my hybrid build in my WRX and I'm running 24 PSI currently with a GTX3076R, soon to be more but the fuel pump couldn't keep up..

[ssssly]

SGt Gator-was referring to folks in that thread at NASIOC blaming their blow engines on AOSs.

[TouchStone]

Touchstone,

Its possible you have a bad / gunked up PCV. So it doesn't close all the way under boost allowing the crank case to become over pressurized thus pushing more oil into the inlet of the turbo. Like others have said a good AOS will likely fix your issues. I personally run the Carwford AOS on my hybrid build in my WRX and I'm running 24 PSI currently with a GTX3076R, soon to be more but the fuel pump couldn't keep up..

I did take the PCV valve out sometime ago and cleaned it in soapy water. Is there a chance I ruined it?

[ssssly]

Extremely unlikely. Unless you freed up a chunk of gunk that re-lodged itself someplace worse than where it came from.

Just pull it out and shake it. If it is dirty you can hear and feel it.

[Pearldrummer7]

They click when you shake them (if they're clean)

[Legacygt21]

The PCV valve is a pretty simple little thing. It is essentially a plunger that blocks the passageway to the crank case from the intake manifold under boost / throttle and opens the passageway under vacuum to relieve crank case pressure. Spraying carb cleaner in there helps dissolve the carbon build up. Or you could just get a new one since they aren't expensive.

[taco20]

http://elementtuning.com/store/#!/Element-Tuning-Competition-Catch-Can-System-New-Higher-Capacity/p/1509856/category=439244

Hey check out what I bought for my build. Element seems to have the right idea for the issue.

[Legacygt21]

That is just a nice catch can setup. It just catches and holds all of the "blow by" oil from the crank case and the heads. An Air oil separator drains that oil back into the engine