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2012 Forester 2.5X, 4EAT; formerly 2006 Outback 2.5i, 4EAT
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Discussion Starter #1
I replaced the cats in my 2006 2.5i 2 1/2 years ago, summer of 2015. Back then I had the P0420 code, even though the car ran fine, and after replacing plugs, wires, A/F, and O2 sensors, it was still there. Replacing the cats (Eastern Catalytic front, Walker rear) resolved the code, and an autopsy showed that there was very little left of the OEM cats--in fact, the rear cat was emptied out.

Last month the car died suddenly and dramatically. In a matter of miles it went from a slight underpower (I was making a mental note to run a tank of gas with Techron) to being unable to pull itself uphill with the accelerator on the floor. No codes (until it actually died), no prior issues, nothing. I had it towed, and the diagnosis came back that both catalytic converters were plugged. I replaced them, and it runs beautifully.

Here's my question: what would cause the kind of fouling I see in the pictures below in such a relatively short time? The car uses about a quart of oil every 1,500 miles. The head gaskets were redone at about 114k miles, and I'm sitting at 148k now; I've had to add a very small amount of coolant here and there, but nothing consistent or alarming.

The first picture is the front cat via the A/F sensor port--note the greyish-white gunk clogging it. The second is a camera shot of the media inside the front cat. The third is a shot of the rear cat from the front. Any suggestions are appreciated. I'd really like to track this down before having to do it again in a couple of years--or sooner.
 

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I simply cannot abide useless people.
2006 2.5i and 2002 3.0 wagons.
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12,305 Posts
Check/change the PCV.

I've never had oil consumption that high in any of my EJ25 engines without a issue needing addressing.
 

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Lawn ornament XT
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Sounds like the front cat flamed out the rear cat.

Your oil consumption issue is certainly part of this- that is a lot of oil to burn off in the cat. But you also need to read the data from the ECU and make sure that there isn't something else going on. You can roast out a brand new cat pretty quickly if something is making the engine run too rich, even without oil leaks.
 

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2012 Forester 2.5X, 4EAT; formerly 2006 Outback 2.5i, 4EAT
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70 Posts
Discussion Starter #5
Are you using a decent name brand gas?
Thanks. The gas varies; the local station available isn't a brand name, but the guy delivering to the station told me that where he picks up runs similar additives to one of the better brands...BP, I believe it was. When I'm in a larger town I hit an Exxon station, though the Kroger station there also seems to run well. Any of the stations I frequent have consistent enough traffic to avoid old gas.


Check/change the PCV.

I've never had oil consumption that high in any of my EJ25 engines without a issue needing addressing.
I changed out the PCV filter back when I had cat issues last time, and just did it again a couple of weeks ago. There was a good bit of oil sitting in the hose leading to the PCV filter, so I'm hoping it doesn't reclog too quickly. Would this be a sign of a problem further back the line?


Sounds like the front cat flamed out the rear cat.

Your oil consumption issue is certainly part of this- that is a lot of oil to burn off in the cat. But you also need to read the data from the ECU and make sure that there isn't something else going on. You can roast out a brand new cat pretty quickly if something is making the engine run too rich, even without oil leaks.
I haven't run RomRaider for quite awhile (probably not since I got rid of the P0420 a couple of years ago, since it was running well); I'll try to do so in the near future to see what other clues I might pick up. Any specific recommendations on what settings to keep my eye out for?

I also wonder if I may have hurt the last set of aftermarket cats by reusing the OEM heat shields with them. I was afraid that without enough shielding, the cats might not get hot enough to work well, and the Rock Auto entry for the Eastern Catalytic front cat said that _some_ of their cats were made to reuse OEM shields. But I did have to modify the shield some to get it to fit, and looking back I wonder if the extra layer might have overheated them?
 

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'17 Outback 2.5i Premium
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163 Posts
OEM catalysts are required to perform to spec for 100k miles, but replacements only need to last 30k; go with OEM if you plan to keep the car.
 

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2012 Forester 2.5X, 4EAT; formerly 2006 Outback 2.5i, 4EAT
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Discussion Starter #7
As it turns out, it looks like my concern is now a moot point. I had started hearing a rattle back in May, and was starting to wonder if the new cats had started working loose (sounded about like a heat shield rattle, mostly at idle). In June the rattle became a scream when I downshifted, and I ended up taking it to a trustworthy independent mechanic.

He called the next day, asking if the oil leak was new (it was). Apparently all four bolts that hold the torque converter in place had come loose, and one had stripped out entirely. When it did, it dented the flywheel, throwing it off balance. The mechanic said the oil leak could be a torn up seal from a bolt rattling around inside, or there is a thin place in the block that it could have damaged; no way for him to tell apart from pulling the engine, and given the car's age he was guessing I didn't want to do that.

They tightened up the bolts, and I'm driving gently and watching the oil until I can replace the car. The mechanic works on a lot of older Subarus (they're plentiful here in WV), and said he's never seen a torque converter loosen up like that. It's disappointing at 152,000 miles, but there it is.
 

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OBW H6 VDC, Tribeca, XT6
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Is it engine oil or ATF that's leaking? other fluids can look like engine oil as they pick up debris and wash off old oil/CV grease from the engine bay and crevices. it is not uncommon to mistake a leak for an engine oil leak when it is not.

if it's ATF then it's probably the torque converter seal. $7 and labor.

this would make the most sense since if the torque converter came loose the TC shaft will have free play where it rides against the TC seal lip.

and said he's never seen a torque converter loosen up like that.
yeah he's right, it doesn't every happen, something caused it. bolts never randomly walk out, there's always something causative. they would have been removed during the headgasket job:
The head gaskets were redone
seems likely they weren't tight enough or stripped/damaged threads.
 

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2005 Outback R LL Bean 3.0 H6 w/ 5 speed sport shift
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As it turns out, it looks like my concern is now a moot point. I had started hearing a rattle back in May, and was starting to wonder if the new cats had started working loose (sounded about like a heat shield rattle, mostly at idle). In June the rattle became a scream when I downshifted, and I ended up taking it to a trustworthy independent mechanic.

He called the next day, asking if the oil leak was new (it was). Apparently all four bolts that hold the torque converter in place had come loose, and one had stripped out entirely. When it did, it dented the flywheel, throwing it off balance. The mechanic said the oil leak could be a torn up seal from a bolt rattling around inside, or there is a thin place in the block that it could have damaged; no way for him to tell apart from pulling the engine, and given the car's age he was guessing I didn't want to do that.

They tightened up the bolts, and I'm driving gently and watching the oil until I can replace the car. The mechanic works on a lot of older Subarus (they're plentiful here in WV), and said he's never seen a torque converter loosen up like that. It's disappointing at 152,000 miles, but there it is.
There are tracer dyes that can be added to the engine oil to enable you to determine where the leak is originating from.
 

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2012 Forester 2.5X, 4EAT; formerly 2006 Outback 2.5i, 4EAT
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Discussion Starter #11
Is it engine oil or ATF that's leaking? other fluids can look like engine oil as they pick up debris and wash off old oil/CV grease from the engine bay and crevices. it is not uncommon to mistake a leak for an engine oil leak when it is not.

if it's ATF then it's probably the torque converter seal. $7 and labor.

this would make the most sense since if the torque converter came loose the TC shaft will have free play where it rides against the TC seal lip.

yeah he's right, it doesn't every happen, something caused it. bolts never randomly walk out, there's always something causative. they would have been removed during the headgasket job:
seems likely they weren't tight enough or stripped/damaged threads.
I didn't look very closely, but as I was wiping down the underside of the engine before taking it in (to confirm that the leak had gotten worse) the fluid was used-oil brown-blackish, rather than the red tint of the ATF that I had just changed a month or two ago. It may be ATF, and if so, that might take the cost of repair down to the flywheel and a torque converter seal, but I've decided to find a replacement. Any car needs maintenance along the line, but this one has nickled, dimed, and dollared me to the point of no return. Someone with more mechanical aptitude and time (I do as much of my own work as I can, but at this point redoing the engine is beyond what I have time and skill tackle) could make this a nice car; it has the first hints of surface rust on the undercarriage, but the body still could have a long life ahead of it. But the engine puts me out on this one.

And I agree, too, that something had to work the bolts loose. I don't think it was the headgasket work, as that was done close to five years and 37,000 miles ago, but maybe it took that long to creep out. I just don't know.
 
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