2005 STI oil burning problem

2gnt2wrx · 11-10-2024, 01:40 PM

Car has under 100k/mi original engine. Noticed it sucked down a half a quart or so of oil in 200miles, smoke comes out of tail pipe only under boost. Stage2+, Crawford v2 AOS. Car doesn’t get driven often. Car runs and drives normal, no noises, or anything that would suggest the engine is blown. I’m getting very frustrated at this point with the situation and looking for advice. Oil used is 5w 40 motul, engine has good oil pressure. Should I clean the AOS out? Stuck oil control ring? Thanks in advance.

What I’ve done so far
-Pulled tmic 35 times and it has oil every time. Except when I ran the AOS to atmosphere. Don’t worry I monitored my AFR’s.

-No smoke out of the oil fill neck when warm.

-installed 3MI AOS drain to turbo drain.

-checked pcv routing… initially I did have a line crossed up by accident but fixed it.

-did an initial compression test before seafoam. 136-143psi on all cylinders.

-Ran Seafoam through intake track.

-Compression test after cyl1- 145psi, cyl2- 139psi, cyl3- 144psi, cyl4- 138psi.

-Leakdown test cyl1- 4%, cyl2- 7%, cyl3- 4%, cyl4 6%.

-cleaned the tmic with gasoline, and drive the car another 120miles and burned another 1/4 quart.

-Pulled exhaust manifold and no oil coming from the exhaust valve seals.

-swapped turbo’s no oil coming from the exhaust side of either turbo.

-Borescoped all four cylinders, noticed a small amount of oil sitting at the bottom of each piston bore.

-Borescoped the intake valves couldn’t see any oil coming from I take valve seals on the o es I could reach.

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AndrewsSubaru · 11-10-2024, 04:47 PM

If your AOS is properly routed/set up you should not have any oil in the inlet or intercooler, even more so because your engine is stock. I installed both IAG and crawford aos's in my cars and they work great.

I'm willing to bet you have a kink/clogged/not proper line somewhere. It sounds like you're not venting properly and under boost pressure you're pushing oil out of the breather ports straight into the inlet. When you ran it to atmosphere whatever oil the aos caught went out instead of being burned

If you triple checked all the hoses the only other thing I could think of is the drain inside the aos is clogged, you could shoot some brake clean in one of the vents and see if anything comes out the bottom, or shove a rag or something in there to try and clean it

2gnt2wrx · 11-10-2024, 05:19 PM

Thank you, I tried blowing through the top and there was some resistance coming through the drain side. I’m
Going to try cleaning it somehow, brake cleaner or gas. I’ll post my findings.

2gnt2wrx · 11-11-2024, 03:17 PM

Pulled everything apart: checked all lines, no kinks, no obstructions, blew through everything all clear, cleaned the AOS with gasoline then brake cleaner, and rechecked all hose routing. Still small clouds u see boost.

TurboRev · 11-12-2024, 01:29 PM

I'd start by giving the AOS a good clean. Make sure the drain and any screens inside are clear so oil doesn't build up and end up getting sucked into the intake when you're boosting. You can use some brake cleaner or compressed air to flush it out. Then, go over all the PCV hoses and the valve to be sure there aren't any tiny kinks or clogs that could be causing pressure issues and pushing oil where it doesn't belong.

Nomiezvr-4 · 11-15-2024, 11:14 PM

Id yank the AOS if you don't track or auto-x the car to see what happens. My car makes 370whp on e85, no AOS i street drive it, haven't had a need for an AOS yet.

AndrewsSubaru · 11-17-2024, 11:53 AM

Did you keep that metal piece under the intercooler? I just remembered I removed it because it was completely full of gunk and I ran the hoses straight to the breathers instead. So I'd check that too.

If it's clear, you could try to run the aos breather port to some kind of plastic bottle (somewhere it won't melt) and see how much oil you catch if you're still having issues. Adding an aos shouldn't cause so much blowby but without seeing the car in person it's hard to say what the issue is

benflynn · 11-19-2024, 10:50 AM

Could it not be a broken ring land? Only sever oil using without noticeable smoke has been cyl 4 ringland. And out of the dozen or so short blocks I have had apart only one had no cracked ringlands.

AlexL · 11-19-2024, 02:20 PM

What was wrong with the PCV initially? If you pressurized your crankcase once upon a time, you may have blown some seals irrepairably and now you have more blowby than normal, which won't be fixed except by taking things apart. I would vent everything to atmosphere, to test, disconnect and plug the PCV. If it's still smoking, that's your rings.

2gnt2wrx · 11-19-2024, 02:23 PM

It’s a possibility but would it be the case if it had good compression and leak down numbers?

Oil appears to be leaking out of the compressor housing of the turbo now.

benflynn · 11-19-2024, 06:50 PM

Oil out compressor can high crank pressure or the pvc is dumping into the turbo inlet. I second the dump to atmo and see what’s up.

Also a boost leak will cause oil past the compressor.

benflynn · 11-19-2024, 06:54 PM

I can’t say from experience leakdown numbers associated with the broken piston. I am very quick to pull one apart since I do my own work and believe anything with oem top ring gap is or will be broken before long. I will say oil loss is the only symptom I have seen from one.

AlexL · 11-20-2024, 09:50 AM

Quote:

Originally Posted by 2gnt2wrx

It’s a possibility but would it be the case if it had good compression and leak down numbers?

Oil appears to be leaking out of the compressor housing of the turbo now.

But it only smokes under boost? A bad turbo seal would smoke all the time.

AndrewsSubaru · 11-20-2024, 04:00 PM

He ran vta already which is why I suggested running into a can or something. You'll be able to tell if it's blowby mix or pushing mostly oil through (I'm guessing it would be oil)

There has to be something we're missing since the compression and leakdown seem ok. I don't know what else it could be other than pcv or turbo

2gnt2wrx · 11-20-2024, 08:10 PM

I ran it to an aluminum can and drove 200 miles, nothing of note in the can.

I’m considering returning the pcv system to stock… which is quite an ordeal since I blocked the pcv valve when I redid my intake manifold. This should eliminate the AOS as being the culprit. There are some reports of people having issues with the Crawford.

danger1138 · 11-21-2024, 05:22 AM

If there was no oil inside TMIC when you dumped/vented the AOS to atmosphere; keep it that way.
Im running IAG AOS; tuned my vehicle with it routed the "street version" way. Everytime i pulled off my TMIC i had oil inside TMIC, on the couplers etc..

I have since routed the IAG aos to the "Comp version"; dumping to atmosphere and there is a stark difference. Very little to no oil inside TMIC & friends.

benflynn · 11-21-2024, 08:39 AM

Quote:

Originally Posted by AndrewsSubaru

There has to be something we're missing since the compression and leakdown seem ok. I don't know what else it could be other than pcv or turbo

I don’t know if I agree.

AndrewsSubaru · 11-21-2024, 12:38 PM

If there was a bent valve, broken piston or a broken ring it would've shown up no? Unless it was poorly maintained and oil changes were extended the likelihood of a stuck oil ring seems pretty low. However it is a subaru and stranger things can/do happen I suppose

cboggess · 11-21-2024, 04:51 PM

I'm betting stuck rings on this one. Yes. You can still have great compression and have stuck rings. I know. Personally. Because I've done it. Yeah, yeah, I know. I was busy with life and kept putting off my oil changes. Yeah yeah, I know. No really. I do know. Seriously. Yes. I'm a dummy. I'm not arguing with you. Anyway...

Here is what I have done in this case, and had success with:
Buy 2 cans of liquimoly engine flush.
Buy some cheap oil you run in your weight
Buy some cheap filters
Buy a can of seafoam or fuel injector cleaner (skip this if you run e85 which I doubt you are doing because I don't think the rings would stick if you were)

Dump can of engine flush in engine. Run for the 10-15 minutes idling as they recommend.
Turn the car off, and tell it you'll see it tomorrow.
Next day drain oil. Remove old filter.
Install new filter. Fill with fresh cheap oil.
Dump half a can of seaform or injector cleaner into tank.
Go for a drive. Just a nice long drive. Don't beat on it. Just drive it.
Bring it home. While it is still hot dump the second can of engine flush in it. Let it idle the 10-15 minutes. Say good night.
Next day drain cheap oil out. Remove filter.
Install new filter. Fill with fresh cheap oil.
Dump remainder of seafoam in the tank.
Drive like a normal person for a few hundred miles.
Go back to your normal, good synthetic oil and good filter.

11-10-2024, 01:40 PM	#1
2gnt2wrx Scooby Specialist Member#: 123625 Join Date: Aug 2006 Chapter/Region: NESIC Location: Dover, NH Vehicle: 2015 WRX Galaxy Blue	2005 STI oil burning problem Car has under 100k/mi original engine. Noticed it sucked down a half a quart or so of oil in 200miles, smoke comes out of tail pipe only under boost. Stage2+, Crawford v2 AOS. Car doesn’t get driven often. Car runs and drives normal, no noises, or anything that would suggest the engine is blown. I’m getting very frustrated at this point with the situation and looking for advice. Oil used is 5w 40 motul, engine has good oil pressure. Should I clean the AOS out? Stuck oil control ring? Thanks in advance. What I’ve done so far -Pulled tmic 35 times and it has oil every time. Except when I ran the AOS to atmosphere. Don’t worry I monitored my AFR’s. -No smoke out of the oil fill neck when warm. -installed 3MI AOS drain to turbo drain. -checked pcv routing… initially I did have a line crossed up by accident but fixed it. -did an initial compression test before seafoam. 136-143psi on all cylinders. -Ran Seafoam through intake track. -Compression test after cyl1- 145psi, cyl2- 139psi, cyl3- 144psi, cyl4- 138psi. -Leakdown test cyl1- 4%, cyl2- 7%, cyl3- 4%, cyl4 6%. -cleaned the tmic with gasoline, and drive the car another 120miles and burned another 1/4 quart. -Pulled exhaust manifold and no oil coming from the exhaust valve seals. -swapped turbo’s no oil coming from the exhaust side of either turbo. -Borescoped all four cylinders, noticed a small amount of oil sitting at the bottom of each piston bore. -Borescoped the intake valves couldn’t see any oil coming from I take valve seals on the o es I could reach. * Registered users of the site do not see these ads.

11-11-2024, 03:17 PM	#4
2gnt2wrx Scooby Specialist Member#: 123625 Join Date: Aug 2006 Chapter/Region: NESIC Location: Dover, NH Vehicle: 2015 WRX Galaxy Blue	Pulled everything apart: checked all lines, no kinks, no obstructions, blew through everything all clear, cleaned the AOS with gasoline then brake cleaner, and rechecked all hose routing. Still small clouds u see boost. Last edited by 2gnt2wrx; 11-11-2024 at 08:50 PM.

11-20-2024, 08:10 PM	#15
2gnt2wrx Scooby Specialist Member#: 123625 Join Date: Aug 2006 Chapter/Region: NESIC Location: Dover, NH Vehicle: 2015 WRX Galaxy Blue	I ran it to an aluminum can and drove 200 miles, nothing of note in the can. I’m considering returning the pcv system to stock… which is quite an ordeal since I blocked the pcv valve when I redid my intake manifold. This should eliminate the AOS as being the culprit. There are some reports of people having issues with the Crawford. Last edited by 2gnt2wrx; 11-20-2024 at 08:41 PM.

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11-10-2024, 04:47 PM	#2
AndrewsSubaru Scooby Newbie Member#: 534243 Join Date: May 2023 Vehicle: 1992 Legacy Turbo 2006 WRX, 2005 9-2x Aero	If your AOS is properly routed/set up you should not have any oil in the inlet or intercooler, even more so because your engine is stock. I installed both IAG and crawford aos's in my cars and they work great. I'm willing to bet you have a kink/clogged/not proper line somewhere. It sounds like you're not venting properly and under boost pressure you're pushing oil out of the breather ports straight into the inlet. When you ran it to atmosphere whatever oil the aos caught went out instead of being burned If you triple checked all the hoses the only other thing I could think of is the drain inside the aos is clogged, you could shoot some brake clean in one of the vents and see if anything comes out the bottom, or shove a rag or something in there to try and clean it

11-10-2024, 05:19 PM	#3
2gnt2wrx Scooby Specialist Member#: 123625 Join Date: Aug 2006 Chapter/Region: NESIC Location: Dover, NH Vehicle: 2015 WRX Galaxy Blue	Thank you, I tried blowing through the top and there was some resistance coming through the drain side. I’m Going to try cleaning it somehow, brake cleaner or gas. I’ll post my findings.

11-12-2024, 01:29 PM	#5
TurboRev Scooby Newbie Member#: 463945 Join Date: Mar 2017	I'd start by giving the AOS a good clean. Make sure the drain and any screens inside are clear so oil doesn't build up and end up getting sucked into the intake when you're boosting. You can use some brake cleaner or compressed air to flush it out. Then, go over all the PCV hoses and the valve to be sure there aren't any tiny kinks or clogs that could be causing pressure issues and pushing oil where it doesn't belong.

11-15-2024, 11:14 PM	#6
Nomiezvr-4 Scooby Newbie Member#: 538322 Join Date: Jun 2024	Id yank the AOS if you don't track or auto-x the car to see what happens. My car makes 370whp on e85, no AOS i street drive it, haven't had a need for an AOS yet.

11-17-2024, 11:53 AM	#7
AndrewsSubaru Scooby Newbie Member#: 534243 Join Date: May 2023 Vehicle: 1992 Legacy Turbo 2006 WRX, 2005 9-2x Aero	Did you keep that metal piece under the intercooler? I just remembered I removed it because it was completely full of gunk and I ran the hoses straight to the breathers instead. So I'd check that too. If it's clear, you could try to run the aos breather port to some kind of plastic bottle (somewhere it won't melt) and see how much oil you catch if you're still having issues. Adding an aos shouldn't cause so much blowby but without seeing the car in person it's hard to say what the issue is

11-19-2024, 10:50 AM	#8
benflynn Scooby Specialist Member#: 515308 Join Date: Jun 2020	Could it not be a broken ring land? Only sever oil using without noticeable smoke has been cyl 4 ringland. And out of the dozen or so short blocks I have had apart only one had no cracked ringlands.

11-19-2024, 02:20 PM	#9
AlexL NASIOC Supporter Member#: 192988 Join Date: Oct 2008 Location: CT Vehicle: 2005 WRB GD Wagon	What was wrong with the PCV initially? If you pressurized your crankcase once upon a time, you may have blown some seals irrepairably and now you have more blowby than normal, which won't be fixed except by taking things apart. I would vent everything to atmosphere, to test, disconnect and plug the PCV. If it's still smoking, that's your rings.

11-19-2024, 02:23 PM	#10
2gnt2wrx Scooby Specialist Member#: 123625 Join Date: Aug 2006 Chapter/Region: NESIC Location: Dover, NH Vehicle: 2015 WRX Galaxy Blue	It’s a possibility but would it be the case if it had good compression and leak down numbers? Oil appears to be leaking out of the compressor housing of the turbo now.

11-19-2024, 06:50 PM	#11
benflynn Scooby Specialist Member#: 515308 Join Date: Jun 2020	Oil out compressor can high crank pressure or the pvc is dumping into the turbo inlet. I second the dump to atmo and see what’s up. Also a boost leak will cause oil past the compressor.

11-19-2024, 06:54 PM	#12
benflynn Scooby Specialist Member#: 515308 Join Date: Jun 2020	I can’t say from experience leakdown numbers associated with the broken piston. I am very quick to pull one apart since I do my own work and believe anything with oem top ring gap is or will be broken before long. I will say oil loss is the only symptom I have seen from one.

11-20-2024, 04:00 PM	#14
AndrewsSubaru Scooby Newbie Member#: 534243 Join Date: May 2023 Vehicle: 1992 Legacy Turbo 2006 WRX, 2005 9-2x Aero	He ran vta already which is why I suggested running into a can or something. You'll be able to tell if it's blowby mix or pushing mostly oil through (I'm guessing it would be oil) There has to be something we're missing since the compression and leakdown seem ok. I don't know what else it could be other than pcv or turbo

11-21-2024, 05:22 AM	#16
danger1138 Scooby Specialist Member#: 279525 Join Date: Apr 2011 Chapter/Region: Tri-State Location: Arkansas Vehicle: 06 Fxt	If there was no oil inside TMIC when you dumped/vented the AOS to atmosphere; keep it that way. Im running IAG AOS; tuned my vehicle with it routed the "street version" way. Everytime i pulled off my TMIC i had oil inside TMIC, on the couplers etc.. I have since routed the IAG aos to the "Comp version"; dumping to atmosphere and there is a stark difference. Very little to no oil inside TMIC & friends.

11-21-2024, 12:38 PM	#18
AndrewsSubaru Scooby Newbie Member#: 534243 Join Date: May 2023 Vehicle: 1992 Legacy Turbo 2006 WRX, 2005 9-2x Aero	If there was a bent valve, broken piston or a broken ring it would've shown up no? Unless it was poorly maintained and oil changes were extended the likelihood of a stuck oil ring seems pretty low. However it is a subaru and stranger things can/do happen I suppose

11-21-2024, 04:51 PM	#19
cboggess Scooby Specialist Member#: 30804 Join Date: Dec 2002 Chapter/Region: SWIC Vehicle: 87 Yugo Red	I'm betting stuck rings on this one. Yes. You can still have great compression and have stuck rings. I know. Personally. Because I've done it. Yeah, yeah, I know. I was busy with life and kept putting off my oil changes. Yeah yeah, I know. No really. I do know. Seriously. Yes. I'm a dummy. I'm not arguing with you. Anyway... Here is what I have done in this case, and had success with: Buy 2 cans of liquimoly engine flush. Buy some cheap oil you run in your weight Buy some cheap filters Buy a can of seafoam or fuel injector cleaner (skip this if you run e85 which I doubt you are doing because I don't think the rings would stick if you were) Dump can of engine flush in engine. Run for the 10-15 minutes idling as they recommend. Turn the car off, and tell it you'll see it tomorrow. Next day drain oil. Remove old filter. Install new filter. Fill with fresh cheap oil. Dump half a can of seaform or injector cleaner into tank. Go for a drive. Just a nice long drive. Don't beat on it. Just drive it. Bring it home. While it is still hot dump the second can of engine flush in it. Let it idle the 10-15 minutes. Say good night. Next day drain cheap oil out. Remove filter. Install new filter. Fill with fresh cheap oil. Dump remainder of seafoam in the tank. Drive like a normal person for a few hundred miles. Go back to your normal, good synthetic oil and good filter.