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Discussion Starter #1 (Edited)
Hey guys I've got a pretty confusing situation. I typically am pretty decent at troubleshooting engine issues, but this one has me stumped.

Let me give you the background, ej253 from a 2006 impreza 2.5I, purchased on craigslist from a wrecked car with 65k miles. Did a timing belt/waterpump and swapped the appropriate sensors to drop it into my forester.

Started the engine, had a smoking issue from the get go. The smoking wasn't TOO bad though, and I had put oil in the cylinders and turned them by hand to lube them up before starting it, so that was expected. Seemed like it was burning coolant too, so suspected a headgasket.

After about 20 mins of runtime, still smoking steadily, the motor let loose. It just started burning oil worse than I've ever seen, HUGE smoke cloud - i shut it off immediately. Not sure anymore if there was coolant burning too, or just oil - the smell and color was predominantly oil.. stink and blue.

Now, this is where things get confusion. I assumed a good ole leakdown test would find my culprit.

Cylinders 1-4 ALL were within 5% of each other, and ALL read good (under 15% leak) on my tester running @40psi or so.

This confused me, so i turned to a compression test.

Drivers side was in the 140's compression on both, within 5psi of each other.
Pass side was in the 160's compression on both, again within 5psi of each other.

I've never seen a engine where the compression test shows different from the leakdown test.

Now, I know i need to tear this thing down and look into it now, but i wanted to see what the subie community has to say on this one. It's a real bummer and I was hoping it was a headgasket at first, but considering its oil that is burning and the rate it is consuming it, I'm just not sure.

Ringlands are a common issue, but those should have been OBVIOUS with the leakdown test and not given me good results.

Oil control ring? valve stem seals? Not sure what else could cause this.

To give you an idea, it burned probably almost 2 quarts within 20 mins of running total. Honestly, i think now it's consuming more like a quart / 5 minutes at this point. It's bad.

Any ideas guys? Like i said I know it's teardown time, I just would like to know what to look for.

Thanks much.
 

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Discussion Starter #3
I just pulled that motor, oil is everywhere. It was drowning in its own fluids.

Oil pooled on the intake valves:


Exhaust ports (all four look like this)


header full of oil. Both sides, all four ports are like this.


Must be some major blowby or something right? I should get the motor apart soon, i can't believe it ran so damn good like that.
 

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2000 obs green
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By the sounds of it the rings are badly worn, all the cylinders are low on compression. I'm not sure though if that would be enough to cause it to burn that much oil. Do/did you have a lot of oil in your air box, from the crankcase?
 

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Discussion Starter #5
By the sounds of it the rings are badly worn, all the cylinders are low on compression. I'm not sure though if that would be enough to cause it to burn that much oil. Do/did you have a lot of oil in your air box, from the crankcase?
Yip, that's where it appears to be coming from. I suspect BAD blowby that is leading to oil getting dumped into the intake through the PCV system.

I'll post up some more post-mortim pictures later!
 

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Discussion Starter #6
Okay, i'm facepalming so hard. The PCV system was hooked up wrong, the pass side VC pcv hose was hooked up DIRECTLY to the intake manifold.

Could this suck huge amounts of oil into the intake and cause this?
 

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Discussion Starter #7
Actually, let me answer my own question. Yes, yes hooking your VC breather up to a vaccuum would act like a huge straw and such a ton of oil into your intake.

Also, yes, that is what your intake would look like, lol.

I'm 99% sure this is my issue, so dumb. At least i can put new HG's on this motor and be done with that.
 

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1996 imp jdm ej20 NA dohc swap
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It's like the mousehunt movie where the mouse hooks up the vacuum hose that the two guys put in the wall right up to the sewage line.... major blowage... lol

Hopefully this fixes it :) Time to clean the pistons and chambers in the heads... lol and part of the exhaust ports in the heads.
 

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Discussion Starter #9
It's like the mousehunt movie where the mouse hooks up the vacuum hose that the two guys put in the wall right up to the sewage line.... major blowage... lol

Hopefully this fixes it :) Time to clean the pistons and chambers in the heads... lol and part of the exhaust ports in the heads.
LOL, yeah. You could say that. I got some more pics of the motor. I'm glad I found this out AFTER i tore the heads off. Pretty much a fail on my behalf.

After looking at the intake manifold again today, i'm almost 100% sure that is where the oil was pouring in through. My worst automotive fail to date, I think.

The port on the IM that I had the valve cover port hooked up to.


The inside of the IM, oil pooled under where that port is.


Heads both look like this:



Headgaskets looked fine:


Cylinders:





The carbon on the pistons seems to flake off in big chunks, I'm guessing that is new from the suck-by (reverse of blow-by).

Thinking I'll clean the tops of the pistons, clean out the intake manifold, get some new gaskets and go back together. Learn something new everyday
 

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Discussion Starter #10
So.. any input on this? I'm about to clean up and slap this thing back together and blame the oil filled IM/cylinders on my PCV routing, i'm pretty confident that's the problem but I'd like other's opinion.

Thanks
 

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Discussion Starter #12
I had the breather from the valve cover directly connected to a vacuum port on the intake manifold.

It's SUPPOSED to go to the intake box, pre throttle body. This spot see's minimal vacuum normally.
 

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95L, 07 2.5i, R6
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You must have been sucking tons of oil from the valve cover directly into the intake manifold during idle. Then when you boosted, the oil sitting in the intake manifold gets blown through the cylinders. Sounds about right from your description that you had the pcv incorrectly routed.
 

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Discussion Starter #14
It's a n/a motor, but yeah basically the same concept when the air flows into the cylinders.

This motors been back together with fresh headgaskets for over 2k miles now, not a single drop of oil or coolant burnt. I love it.

 
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