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Old 03-18-2021, 03:07 PM   #1
akupenguin
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Join Date: Jul 2019
Default ej253 rebuild

Hello again! In the near future I'm planning on getting the engine in my 07 legacy wagon (na) rebuilt. The goal is to eliminate or at least reduce the oil consumption issue it has. Judging by the results of a couple of leakdown tests I'm guessing it's the rings. There's also a couple of unknown oddities with the engine from before I owned it, one of them being an obviously replaced right cylinder head. Also get high fuel trims and an amount of fine knock correction. I know I could swap for a jdm engine for cheaper but I feel like that brings more unknowns into the equation.
Anyway I was going to ask if there was anything I should consider having done while it's apart or replaced with non-stock. Thanks in advance.

Oh and it'll have 100k on it in ~1k
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Old 03-20-2021, 10:47 PM   #2
serrilion
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Location: Shoreham, VT
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2002 TS
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So your experiencing piston slap? The rings going bad at 100k surprises me, that motor is normally a very stout motor along with having the head replaced.

Are you sure its the pistons and not the valves? Is the motor in correct timing as well? As for the higher fuel trims, it is trying to keep the motor from exploding as its detecting knock. I would try to replace the knock sensor to make sure its not bad.

As for replacing parts while in there. If your tearing it down, make sure you use good MLS head gaskets, get a timing belt kit with a new water pump, idles and tenchioner included. Gates is my preference normally but everyone has a brand they prefer. An engine rebuild gasket kit is always handy as it replaces gaskets that are now going on 14 years old.

basically think what do I need for the next 100k when the belts due again
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Old 03-21-2021, 09:24 PM   #3
Pix3L8
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Quote:
Originally Posted by akupenguin View Post
Hello again! In the near future I'm planning on getting the engine in my 07 legacy wagon (na) rebuilt. The goal is to eliminate or at least reduce the oil consumption issue it has. Judging by the results of a couple of leakdown tests I'm guessing it's the rings. There's also a couple of unknown oddities with the engine from before I owned it, one of them being an obviously replaced right cylinder head. Also get high fuel trims and an amount of fine knock correction. I know I could swap for a jdm engine for cheaper but I feel like that brings more unknowns into the equation.
Anyway I was going to ask if there was anything I should consider having done while it's apart or replaced with non-stock. Thanks in advance.

Oh and it'll have 100k on it in ~1k
hey man I just read your post and it sounds similar to what I just did to my own engine. about a month ago I replaced my 06 ej253 (for oil consumption) with a OEM shortblock and rebuilt heads. I am by no means an expert on this topic but if you are ready to invest some money in the car I would 1: get both heads checked by a machine shop (mic'd, pressure tested, possibly valve job etc), 2: decide if you want to just simply replace your short block with a stock unit or rebuild your existing one, and finally factor in that whatever you think your budget will be, tack on another 25% or so on for "unforeseen circumstances". the last thing, if you do it yourself you'll save a heap of cash BUT its quite a bit of time and commitment if you've never ripped into a subie engine before.
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Old 04-12-2021, 05:29 PM   #4
OGspartan
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Quote:
Originally Posted by Pix3L8 View Post
hey man I just read your post and it sounds similar to what I just did to my own engine. about a month ago I replaced my 06 ej253 (for oil consumption) with a OEM shortblock and rebuilt heads. I am by no means an expert on this topic but if you are ready to invest some money in the car I would 1: get both heads checked by a machine shop (mic'd, pressure tested, possibly valve job etc), 2: decide if you want to just simply replace your short block with a stock unit or rebuild your existing one, and finally factor in that whatever you think your budget will be, tack on another 25% or so on for "unforeseen circumstances". the last thing, if you do it yourself you'll save a heap of cash BUT its quite a bit of time and commitment if you've never ripped into a subie engine before.
I find myself at this exact crossroads at the moment for my 06 2.5i. I am most likely gonna go the OEM shortblock and rebuilt heads route too. With that being said, is it necessary to follow any break in procedure given that it's gonna be a brand new shortblock?
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Old 04-14-2021, 07:59 PM   #5
Pix3L8
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Quote:
Originally Posted by OGspartan View Post
I find myself at this exact crossroads at the moment for my 06 2.5i. I am most likely gonna go the OEM shortblock and rebuilt heads route too. With that being said, is it necessary to follow any break in procedure given that it's gonna be a brand new shortblock?
this is what the parts guy at the Subie dealer told.
1. dump oil after the first startup to remove any impurities inside the block leftover from manufacturing
2. dump oil after 3-5 hundred miles
3. dump oil again after an additional 5 hundred miles
4. use traditional oil initially rather than synthetic as to let the rings seat properly
5 after 1000 to 1500 miles you can switch over to a trusted synthetic
6. it is normal to see some oil consumption while the rings seat (I lost half a quart in 500 miles) then this stopped when they seated.

I drove the car gingerly for the first 500 miles making sure to engine brake (downshift) when I could and not let it idle for more than a minute or so. VARY YOUR RPMS don't just get on the highway and cruise. I have another thread going with some problems I have with the car but I have ruled out the new motor and am chasing electric gremlins, the point being this method worked for me with zero issues. There are all kinds of theories out there on how to break in an engine. on my bronco, I rebuilt the engine and drove it like a bat out of hell and that worked just as well for me so who really knows what the "correct method is", but Subaru gave me a specific method they said they do with all their short block installs so I followed it.
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Old 05-12-2021, 03:43 PM   #6
Lega-C
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I'd replace the water pump for sure and make sure the coolant system is functioning properly.
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Old 08-15-2021, 06:25 AM   #7
Pacomartin
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I inherited a 2007 2nd generation Impreza with 62,000 miles and a 2.5-liter EJ253 engine. I became aware of the head gasket issue with these engines so I replaced an 8 year old battery and flushed the coolant and the transmission fluid, changed the motor oil and replaced the air filter and cabin filter. I read that any old fluids or acid from old batteries can shorten life of head gasket.

Is there anything else I can do? My mechanic said that the head gasket failure is inevitable and I won't be able to stop it with anything preventive.

A previously owned Subaru by my father was a 2003 Legacy which had it's head gasket replaced on 3 January 2011 with 101,935 miles. The car was sold.
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Old 08-15-2021, 06:25 AM   #8
Pacomartin
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Quote:
Impreza Sales 5th generation
7,170 2017 month avg peak 8,546 in May 2017
6,367 2018 month avg peak 8,154 in Aug 2018
5,535 2019 month avg peak 7,519 in Aug 2019
3,636 2020 month avg peak 4,654 in Aug 2020
------
2,771 Jan 31, 2021
2,708 Feb 28, 2021
3,636 Mar 31, 2021
3,447 Apr 30, 2021
2,946 May 31, 2021
1,657 Jun 30, 2021
706 Jul 31, 2021
Although the assumption is that once the chip shortage is over, Subaru will return to producing Imprezas, but I have my doubts. For one thing, the chip shortage may last two years. I also fear that Crosstrek sales are so strong that the Subaru executives will not want to risk them by producing a lot of Imprezas.

Last edited by Pacomartin; 08-15-2021 at 06:34 AM.
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Old 08-18-2021, 03:04 PM   #9
car_freak85
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EA63 , EA81T, EJ20G,
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Replace all the PCV hoses and tees. We had pretty bad cold-start piston slap on our '99 -253 and it turns out the system was basically fully blocked in a couple spots from coked up gunk.
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Old 08-20-2021, 11:09 PM   #10
benflynn
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I have a piston slap after everything in the world 06 253, slapped forever now, pistons looked ok, replaced with 100mm npr pistons and still slaps. Been reliable though, made through 2 kayaker owners driving it everywhere. Can’t wait to sell it, I should send it up north to my brother, they wouldn’t know what to say with a completely rust free southern 06 manual forester
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