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2004 Subaru Outback LLBean
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53 Posts
Discussion Starter · #1 ·
Hey everyone I’m Andrew I’ve been a member for a few years now but don’t post much. We’re a Subaru family and my daughter is getting her learners permit in the spring so I figured her first car should be an Outback—sweet!

I picked up this 2004 Outback LL Bean edition for $800 (the dude probably got the better end of that deal lol). It was ran low on oil and developed a mystery knock. My question is would anyone be interested in following along as I pull the engine down and rebuild it?? I know my way around the 4 cylinders pretty good but the H6 is new to me so I’ll learn as I go and probably have a lot of questions for you folks.

If there’s interest I’ll post up some pics and such as I chip away at it. It’ll be a great project to get me through the winter. Anyway thanks for your time,

Andrew
 

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Premium Member
2020 Onyx
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19,580 Posts
Repair/build threads are always fantastic - many more views than comments, and may be a super helpful resource for those who follow for years to come - so PLEASE do a project thread. I think some project threads spanned years because the work started and stopped here and there but even then it's gold for posterity. Sometimes the "what can go wrong" parts are the most essential.

Even for those of us who will never rebuild a motor, it's a fascinating thing to witness.
 
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On the Super Mod Squad
2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
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28,368 Posts
ez30 rebuilds don't always turn out,

cheaper / easier/ is to get a JDM ez30 with the metal intake, and drop it in. (with a little extention for the north american brake booster, as the JDM is in-front of their right hand driver).
plastic intake is from the later EZ30, that is not drag / drop...and not actually "faster" to drive anyway). the metal intake ones are marked in JDM use years 99-2002,

alternatively, from a rear end crash, that you can hear run. (north american spec year 2001-2004)
 

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2004 Subaru Outback LLBean
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53 Posts
Discussion Starter · #7 ·
ez30 rebuilds don't always turn out,

cheaper / easier/ is to get a JDM ez30 with the metal intake, and drop it in.
Good to know thanks for the help. Any particular reason they don’t turn out well? I’m definitely open to the JDM option. Was kinda hoping I’d find the smoking gun with this engine and just fix it but I’ll have to weigh out the cost—like you said I might be money ahead with a replacement engine.
 

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Premium Member
2020 Onyx
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19,580 Posts
You'll be pulling the old engine either way right?
 

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On the Super Mod Squad
2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
Joined
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28,368 Posts
Good to know thanks for the help. Any particular reason they don’t turn out well? I’m definitely open to the JDM option. Was kinda hoping I’d find the smoking gun with this engine and just fix it but I’ll have to weigh out the cost—like you said I might be money ahead with a replacement engine.
it seems there is a lot more going on in the way the DOHC H6 is put together and its workings than its plain jane EJ25 of the same era.

from those that have done many EZ30 head gaskets on this on this board, its a arduous journey to get it buttoned up properly, and the known good JDM is so cheap to buy in comparison.

this vs. doing a plain old simple Ej251 or Ej253 that one can easily estimate 10 hours, plus the some DIY head polishing or a trip to the paid machine shop with them.

(& all my dogs, have all loved subaru wagons)
 

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2002 Outback
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819 Posts
Not to discourage you from rebuilding but you may want to look over Cardoc's Sleeper VDC thread and note that even as an expert Subaru mechanic with all of the tools and facilities at his disposal, he chooses the JDM route instad of a rebuild. I've rebuilt a few 2.5's and a few other maker's engines but I'd have to think hard about attempting an H6.
 

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Premium Member
01 VDC, 05 R Sedan, 06 BAJA EJ257
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18,806 Posts
The parts for the H6 are high. The time to do a rebuild is long. If a bearing is damaged there's metal everywhere which would mean a THOROUGH cleaning of the block and heads. You'll need either a new crank, or a turn and polish of the original. Turn means sizing the bearings correctly. Then there's the possibility of scoring on the cams.

Either way, a JDM is quick, a rebuild will keep you busy.

Here's the FSM. Just got the H6 section.
 

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Registered
2022 Outback Touring XT Forest green
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90 Posts
Get a replacement engine like many are saying. Cheaper and much less down time and in the end you will more then likely buy the replacement anyway after money spent on an atte rebuild and utter frustration.
 

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Premium Member
01 VDC, 05 R Sedan, 06 BAJA EJ257
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18,806 Posts
Another thing - you can get any 30d engine that is not AVCS and swap your current intake manifold and harness over to it. The plastic intake manifold tends to indicate that the engine has AVCS. You have to pay attention to the posting and see if the solenoids for the oil control are mounted on top of the heads.
 
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