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Old 10-24-2015, 09:07 PM   #1
keyoutback
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Default EJ25 SOHC stock build advice needed.

Hi Everyone!

Kinda feel embarrassed asking after having read about, and seen all these big power big budget builds!

I am quite an experienced wrench in general, but this is my first Subaru engine rebuild, so need some detailed advice.

The backstory:
Step-Son's 2001 Outback EJ25 SOHC motor with 162k miles, split the radiator top tank and had a major overheating event. Headgasket breached into coolant passage on #1 cylinder, and also contaminated the oil.
Removed the engine, replaced the HG's and timing belt set and oil, and replaced the motor, but all was not well. Rod knock occurred after 20 miles or so. Compression was about 175psi across the board, and oil pressure was still ok. Drained the oil and it looked like odd...



Pulled the motor again and found #2 and #3 rod bearing spun.

#3 had welded itself to the rod..
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Old 10-24-2015, 09:36 PM   #2
keyoutback
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#3 rod journal was not pretty...



#2 rod bearing was stuck to the crank...





So, with the carnage visible, we are on a tight budget to get this rebuilt... Nothing fancy or expensive, just do it right so it will last at least another 100k/5 years to get the Step-son thru Graduate School!

Now down to the details... and questions.
The crank will need to be assessed and reground if possible... it looks like it will clean up on the mains ok, but I am concerned about #3, as it reads oversize with all that transferred material!

I am a little unsure on this whole A and B bore sizing, and how to measure and assess what the block needs.
I have Micrometers that measure to 0.0001" and a Boregauge that measures to 0.0005".

My first issue is here is Southern California... measuring the parts at 68degF or 20degC has proven difficult! Best I have seen is 74degF, and that is what I did so far.

Questions:
1/ How big a difference concern is my temp increase over 20C?
2/ When measuring each bore... do I zero my Bore gauge at the LARGER size and measure the difference?

Any input from you guys here will be a great help!
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Old 10-24-2015, 10:08 PM   #3
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#1 I have no idea. Maybe someone else does
#2 If you mean piston to cylinder wall clearance, you would measure the bore diameter at a spot in the cylinder according to Subaru or piston manufacturer specs, then measure piston diameter and subtract the two to get your clearance.

To do this right, I would replace the crank and send the rods to the manufacturer to be tested and refurbished if possible.

It appears you have a lot of reading and learning to do before tackling this on your own.
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Old 10-24-2015, 11:19 PM   #4
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What's your budget?

New OEM rod and mains about $250. Recondition rods $70. Hone $75. Polish crank $60. New piston rings $100? New crank? $300. Hondabond $14. New Pistons? $300-500. Bore for new pistons $150. New OEM shortblock $2000. All new seals, head gaskets, $300-500. Resurface heads $100....
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Old 10-25-2015, 01:02 AM   #5
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Thanks for the input.

Budget is not to spend more than the car is worth... If I can keep it under $1000 with me doing the checking and assembly I will be happy.
Crank will need a regrind, as the mains and rods are definitely scored.

I am scouting engine machine shops in Orange County.
So far, R & D, in Costa Mesa, CA, had some good answers.
They said:
$90 to regrind the crank.
$200 to bore and hone the block with a torque plate.
$18 to resize the rods each.
$40 to hot tank the block.
They also said that sometimes a rod bearing issue like this will push the mains out of line, and so might need a main align hone at $300... could that be so?

Anyone else who knows Subaru's?

Remember, this is a stock 165hp build, so I don't think we need to go crazy..
Not sure if the block needs to be bored... my initial measurements look ok.. as I can see all the OEM honing marks right to the top ring.
Maybe I can get away with a light hone and re-ring the original pistons.
If not, what is a good budget cast piston?

Assuming that the at least 2 rods need resizing, does the rotating assembly need rebalancing?

Last edited by keyoutback; 10-25-2015 at 01:15 AM.
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Old 10-25-2015, 01:14 AM   #6
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This is an example of the bores... shows hone marks and the wear spot from the piston skirt... remember this is 162,000 miles.



The same bore piston after a light wipe down look like this.
Red mark is the 37mm line down from the piston crown that Subaru says to measure the skirts at.



I will double check my numbers tomorrow and post them.
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Old 10-25-2015, 09:49 AM   #7
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Step #1 is to measure the mainline. You have the tools so it would benefit you to do this yourself. A good average diameter for the main tunnel is 2.520". Carefully clean the case half parting surfaces of burrs and debris(absolutely no air powered tools), torque to specs and measure each hole with your bore gage. Anything over 2.520" will increase your main clearance accordingly, and main clearance is important on a Subaru. If it's too much over that, all things considered, get your self a better core to rebuild. I am not a fan of line honing Subarus for many reasons. If it's ok, THEN have your crank checked out by a competent machine shop. That crank suffered a lot of damage and could be either bent or cracked. If it's grindable, buy .25mm bearings, torque them in the block, bore gage their i.d. and have the shop grind it .0015" max clearance. I would suggest even tighter on a stock build. If the shop gives you a blank stare when you describe this procedure, find a shop who understands.
Aluminum is very sensitive to temp. Even leaving a block on the floor overnight versus up on a table makes a difference. As long as all your parts and mics are at the same temp, you are simply comparing differences between pistons and cylinders and that will remain relatively constant at different temps. Stock build I wouldn't worry too much about a little extra PTW, most people would be very surprised at what new cars leaving the factory have for actual ptw versus what the factory SAYS they have.
I would not recon that one rod, it looks way past recon-able. Bottom line, if you can't find a shop that speaks Suabru, get a better core that you can simply re-ring with new bearings without having to rely on a lot of machine work.
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Old 10-25-2015, 10:34 AM   #8
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^+2 or just get a running motor and not mess with a rebuild. With a 1k budget I'd lean towards getting a running motor vs rebuild for stock HP
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Old 10-25-2015, 11:23 AM   #9
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Dont think spun bearing was anything you have done. Diluted oil must have allowed a bearing to chirp plus coolant eats away at the friction material. So if it sat long, which it may have by looking at the rust on the valves. Not a huge surprise.

Grinding the crank is not worth the time or hassle. These are 280 new, new rods 40. Reality is that you are not a pro machine shop and not equipped to do any of the measuring. Save the time and energy.

On a used sohc block a/b pistons wont make a difference. In fact All Nippon replacement pistons are B grade.

Which brings to another point. New set of pistons and rings is 130$. Only catch is they are not Cali Spec pistons nobody makes them aftermarket. If you show top of piston i'll tell you if its cali or national.


This is not a race car so my recommendation to you is Hone/Deck the block.

Throw a new crank with some std bearings and let it roll. Recheck with plastigauge to be safe but once again. This is not a race car, you worrying about 20 degree difference is overkill and a waste of man hours.

Make sure to pull all galley plugs on the block and clean all the metal out. Clean loctite as it tends to fall down in hole.

Hone/Deck 140
Crank 280
2x Rods 80
DNJ Bearings 50
Nippon Pistons 130 Or Just re=ring for 30$.
~800 out the door and will outlast rest of the car by a mile.

subarupartsheadquarters.com has by far best prices. lmk if you need help with PN.
Dont forget new case bolt sealing washers

PS: DNJ parts are cheap and work, many made in japan. Never had a problem with bearings or rings. Dont overthink it.


Also pop the oil pump off and check rotor bolts. Better yet open up the pump and check for any major scoring.

Last edited by al_s14; 10-25-2015 at 11:35 AM.
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Old 10-25-2015, 01:09 PM   #10
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Thanks everyone for the input so far!
I will take it all onboard!

Here is some more info... cos we love carnage pics.

Here is the HG that popped on #1 that started this mess...


The car sat for a few weeks until I could get to it, and as a result, #1 bore had some marks on it, like this.


Upon measuring the bores and pistons #1 was the worst, as I kinda expected.

Here is what I did for measuring #1, so you guys can crit/comment.
This was done at 74degF.

#1 bore and piston is "B" spec.
Bore spec says 3.9171" to 3.9175".




I set my Micrometer to 3.9175", and then zero'd my bore gauge to that.
As per Subaru FSM, I measured the bores at:
10mm = +0.0010
45mm = +0.0005
80mm = 0.0000
115mm = 0.0000

Now, what confused me a little was the piston...
Subaru spec for a B piston says 3.9163 to 3.9167 at 37mm down from top.
My WORN piston reads 3.9169???

So, on my #1 cylinder I have:
Bore max is 3.9175 + 0.0010 = 3.9185.
Minus Piston size of 3.9169.
Piston to Bore clearance = 0.0016" which is under the 0.0020" minim... by a bit, but not much.
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Old 10-25-2015, 04:35 PM   #11
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I will get to checking the block bore tomorrow...

Now to the crank.
Can I get some more input on regrinding vs replacing?
If a regrind is only $100 or so, why not?

I double checked my measurements today...
Stock spec of MAINS say 2.3619" to 2.3625".
Sizes measured on stroke and 90deg to stroke.
#1 = 2.3618 to 2.3617
#2 = 2.3618 to 2.3617
#3 = 2.3620 to 2.3620
#4 = 2.3620 to 2.3619
#5 = 2.3621 to 2.3622

These are only just under the minimum spec, so I think a minimum regrind would be fine.

The rod journals spec is 2.0466" to 2.0472".
Again, these are measurements taken on stroke and 90 deg:
#1 = 2.0464 to 2.0465
#2 = 2.0441 to 2.0455 (this bearing spun.)
#3 = * spun, could not measure due to bearing material transfer.
#4 = 2.0465 to 2.0466.
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Old 10-25-2015, 04:45 PM   #12
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Ok, just measured crank run out and this might be the clincher.

Removed main bearings 2, 3, and 4.
Wiped crank and bearings clean, and lubed bearings 1 and 5.
Placed the crank in place.
Set up my dial indicator on main journal 3. Dial indicator only reads to 0.001"

Upon rotating crank I am getting 0.005" thru a 360deg rotation.
Subaru FSM says 0.0014" max.

Checked bearing 1 and 5 for reference and get virtually 0 movement.
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Old 10-25-2015, 05:04 PM   #13
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Any crank that has spun a rod journal that badly is going to have some main runout. 2 whacks with a radius'd chisel and it'll be straight again. I've ground cranks for over 30 years, worst crank I straightened had .050" so .005" is nothing. Some hack shops will just grind a bent crank straight, wrong approach. The reason I am for a better core to rebuild is I see horrendous machine work, especially Subarus, as shops do not upgrade their equipment and it's all old and worn out since it was new in 1965. Your block needs so much work, the quality of the build will all be up to the quality of the machine shop. If you can get 10 local people to say Shop X does perfect Subaru work, then I'd change my opinion. Just sayin'.
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Old 10-26-2015, 12:00 PM   #14
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Quote:
Originally Posted by al_s14 View Post

On a used sohc block a/b pistons wont make a difference. In fact All Nippon replacement pistons are B grade.

Which brings to another point. New set of pistons and rings is 130$. Only catch is they are not Cali Spec pistons nobody makes them aftermarket. If you show top of piston i'll tell you if its cali or national.
Cali pistons?
This IS a Cali car as far as I know...
What is the difference?

For clarity, here is mine.


Each piston has WM1 stamped on the lower half.
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Old 10-26-2015, 01:38 PM   #15
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All the sites just say that the NPR pistons are 99.50mm...
I am wondering if I can get away with a light hone and fit these...
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Old 10-26-2015, 05:53 PM   #16
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Quote:
Originally Posted by Motion Machine View Post
Step #1 is to measure the mainline. You have the tools so it would benefit you to do this yourself. A good average diameter for the main tunnel is 2.520". Carefully clean the case half parting surfaces of burrs and debris(absolutely no air powered tools), torque to specs and measure each hole with your bore gage.

Did this today, but the ambient temp was 84degF.

Set my mic at 2.5200" and zero'd my bore gauge to that.

Checked every bearing surface at thrust, and 90deg:
Minimum was +0.0005 and Max was +0.0010
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Old 10-26-2015, 09:00 PM   #17
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The mainline is definitely big, you can subtract about .00015" for the 84 degrees but it's still on the big side. In a perfect non-budget world, it should be line bored but you can also install .25mm bearings, measure the i.d. and have the crank ground to give you .0015". It will be over "spec" but this is a common practice if you want a specific clearance. Again, assuming you can find a good grinder. Going larger than the book says is not unusual. I am doing an Alfa right now this way (also aluminum block) and I need to grind the crank .0005" larger than the oe size to give it .0015" clearance, on both mains and rods. The block line bore measured at the top of the spec, but not over, and I re-sized the rods to middle of the road. Most of time extra clearance is a result of aftermarket bearings not being as thick as they are supposed to be. A bearing only .0002" thinner will give an extra .0004" clearance.
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Old 10-26-2015, 10:15 PM   #18
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Ok.
An Alfa... Mmm... no we are talking... here is mine...
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Old 10-28-2015, 11:33 AM   #19
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So, crunching numbers on the crank mains is tricky...
If I buy a new crank, and put STD size mains in... I risk being on the high side of oil clearances out of the box!
If I have the old crank refurbished I can have the crank custom fit to my block mains...
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Old 11-02-2015, 10:32 AM   #20
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Quote:
Originally Posted by keyoutback View Post
Cali pistons?
This IS a Cali car as far as I know...
What is the difference?

For clarity, here is mine.


Each piston has WM1 stamped on the lower half.
Those are national emissions. Cali Spec SOHC has "dome" shaped pistons. It may not have been available for your year EJ, but i had to ask just in case. In any case i'ave used National in a cali spec engine without issues. Just cant say for sure how it would impact emissions.

NPR 99.5 will be just fine. Just be careful there are a lot of piston sets that are advertised as NPR but fine print shows its the rings that are npr and pistons themselves are china knock offs.

NPR is factory supplier of pistons for most older subaru/nissan engines. I swear by NPR.

Last edited by al_s14; 11-02-2015 at 10:55 AM.
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Old 11-02-2015, 10:51 AM   #21
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Quote:
Originally Posted by keyoutback View Post
So, crunching numbers on the crank mains is tricky...
If I buy a new crank, and put STD size mains in... I risk being on the high side of oil clearances out of the box!
If I have the old crank refurbished I can have the crank custom fit to my block mains...
Like i said, i think youre over engineering a grocery getter and will only end up with a bigger headache than you started with. Being on a high side isnt going to cause world to come to an end. High side on mains will still keep your oil pressure where it needs to be. Thats what's really important.

So lets say this build lasts 100k instead of 130k. By then your bores will be finished. 250k plus on original bore is crazy. You'll need new guides, probably a valve or two. List goes on . Rest of the car will be falling apart. Just doesnt make sense to go balls out on the block if everything else is not up to par. And if you decide to redo every little bit of this engine then your budget...forget about it...


PS: if your shooting for such long term plans definitely deck the block. It may be flat with a straight edge but i am willing to bet you have pitting on the head gasket compression ring area.

In fact i can actually see it in your picture where its cleaned up.
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Old 11-02-2015, 12:23 PM   #22
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Awesome info, THANKYOU!
My pistons are dished... so maybe there was no difference on this model year.

Yes, makes sense the block will be decked while it is at the shop, as you are correct, there is some marking on the fire ring area.

I know this isn't a 500rwhp build, and so a little unusual/boring in this section!
However, I have learned thru past builds that the details from big power builds apply well. The devil is in the detail, and I think that the small details that make a difference.

Could I get info opinions on the Connecting rods?
I cannot find a definitive rod size anywhere..

Here is #2 that spun...
Caps side..


Rod side.


And #3...
Cap side.


Rod side..


I have seen worse resized, but am concerned about having them resized and would I need to have the assembly rebalanced... Indeed, would I have to if I replaced them??
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Old 11-02-2015, 04:04 PM   #23
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Usually if the bolts and whole cap has not turned blue youre ok to reuse. Granted surface is untouched....I would discard all these...

Your cheapest option may be used sti rods. Looked it up and Outback rods are about 57 each, STI rods are 45. New.

I am sure someone wouldn't mind selling a set for 30 each.

Keep in mind your wrist pin bushing may have some wear on it as well. New used rod set may be a decent option.
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Old 11-02-2015, 07:47 PM   #24
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I hav'nt seen any one say get a new oil cooler if your motor has one ,the WRX's do . any time you spin berings a new oil cooler is needed ,some even say a new oil pan ...but you can clean those up pretty easy . I have used new cranks with the +.025mm mains (king bearings) and have met the clearance spec called out by Subaru. gurus on here say never to build a used block ...but that is for turbo motors. you are going to need new head bolts too as im pretty sure all subys use torque to yield bolts ,which shound not be reused. maybe the sohc motors are totally different
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Old 11-02-2015, 10:54 PM   #25
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Quote:
Originally Posted by wrx1392 View Post
I hav'nt seen any one say get a new oil cooler if your motor has one ,the WRX's do . any time you spin berings a new oil cooler is needed ,some even say a new oil pan ...but you can clean those up pretty easy . I have used new cranks with the +.025mm mains (king bearings) and have met the clearance spec called out by Subaru. gurus on here say never to build a used block ...but that is for turbo motors. you are going to need new head bolts too as im pretty sure all subys use torque to yield bolts ,which shound not be reused. maybe the sohc motors are totally different
Correct, ditch the oil cooler , and pan at the minimum. In fact aftermarket pans are so cheap its not even worth the time to clean the oem one.

SOHC dont have a cooler though.

There is no subaru out there that is torque to yield bolt. All head bolts are ok to reuse so long you do not exceed the turning angle . Sohc has special center bolts, typicaly marked blue on the heads.
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