I may have found the short answer. This was on wiki.

“EJ259

Usage: 2004 Legacy, Legacy GT and Legacy Outback (Only Sold in California and New England). Also sold in 2005 Legacy and Outback non turbo models. Engine has a unique setup, most notable is the oval, single port exhaust, three catalytic converters and five air/fuel and oxygen sensors. These engines were also all drive by wire (DBW), and had a three piece intake manifold with a tumble valve in the center section.”

 

You can swap the heads and intake and use the block in anything, at least in the same generation and probably others.

 

That’s good to know.

Guess I need to decide whether to just sell engine as a good running engine for someone that needs it, use the short block in something else or find a 2004/2005 California car that used the JS259 to install it in.

Not sure I want to go down the rabbit hole of dealing with an orphan car that can be hard to keep running properly.
Had a 2004 Toyota Camry California car that was problematic. Catalytic converter was dealer only. $$$$

 

From my research, it appears that the pistons are different on the EJ259 then on the EJ251.
Anyone know if you can use the EJ251 heads on the EJ259 block without changing the pistons?

Anyone swap pistons on the EJ motors before?

I might be willing to swap piston and install new rings, but I’m not willing to split the case. That’s a bridge too far for me.

There is a thread by Regno from 2020 on UltimateSubaru.org that touches on these issues, but I don’t feel like it’s a yes or no on wether the pistons NEED to be swapped.

 

That is a question best left answered by others you may need to wait a bit for an answer from

I haven't seen @cardoc , @Toad442
Maybe even @seagrass and I can't remember who else ATM.

I'm under the belief that so long as it was not a turbo or DOHC, the pistons wouldn't need swapped. I don't know for sure if they do even if it was.
Unfortunately I do not know enough about these other engines to make that determination.

 

The answer may have been in the thread on ultimatesubaru.org.
The user that seems the most knowledgeable states:
“1. Use pistons that match the heads - put whatever piston in whatever hole - doesn't matter.
2. Use new rings.
3. Turn key. “

Takeaways I gleaned from the thread are:
used pistons that match the heads are ok.
Use good quality new rings.
Nothing really fussy about it, just normal good assembly practices.

Seems to be a plethora of opinions. And the JS259 is a 1 off oddball, so hard to find someone with a bunch of exp on it.

 

I have a car I bought for parts with an EJ259. Couldn’t hear it run due to bad computer… was a flood car. Oil and other fluids were clean, no evidence of water.
So, got a computer cheap, popped it in and engine started. Noisy on start up for a few seconds…. May 5 or so, then quieted down. Ran for a minute then got some noise from throw out bearing.
With clutch pedal depressed at idle, quiet. Run the rpm’s up a bit, I hear what sounds like a bearing rattle or piston slap that quiets as I drop back down to idle.
sounds like rod bearings. But my experience in Subarus is a bit lacking.
Other background I know, head gaskets done recently, and engine was 1.5 qts low.

Any thoughts on how to pinpoint this? Any possibilities on causes other than bearings?

If rod bearings, is it worth the freight to do rod bearings and rings? Chances of getting away with just rod bearings?
Based on my reading, I’m not splitting the case. A bridge too far IMHO.
Thoughts and ideas. Thanks!

 

Is the noise there with the clutch in? If it's not then it could be the release bearing.

If it is the engine, and a rod bearing, then either rebuild or replace. You'll not find one of these engines easily. Depends on where you are.

Changing bearings, you'll be splitting the block.

 

Not sure it’s a rod knock. Nothing audible at low rpm. Noise goes away at higher rpm. About 2-3000 rpm is where the noise is.
Doesn’t seem like a rod knock to me. But what the hell do I know! 😎
Anyone out there experience something like this?
I may just spend $40 on an oil analysis to see what’s going on internally before I try to use this engine.
I took a video with sound, but can’t seem to be able to upload.

 

You have to put video on a server like YouTube or Drive and then link it here.

 

ok, I splurged $40 and had Blackstone do an oil analysis. Anyone know how to read these for Subaru? Iron is pretty high and aluminum is a little high. No excess copper, lead or tin showing up. If main or rod bearings are wiped, wouldn’t they show up? Wonder if iron could be from cam/lifters?

 

are you trying to run the EJ259 of 2004 in the body of the 2002 with the 2002 ECU? or is it still in the 2004 body with the 2004 ECU?

(updated thread title, from gen 4 (2010-2014)

to gen 2 (2000-2004)

 

It is still in the original car. 2004 Outback with Cali emissions. I may break it done to the short block, if the bottom end appears ok.

 

So, maybe an idea from left field a bit. Change the oil, like a heavier thicker oil. If you google "subaru piston slap thick oil" you will find plenty of stuff to read. I think the first step is to confirm it is inside the engine (pistons, value train, or rod bearings) or something outside the block/heads (timing belt, pulleys, clutch, power steering, alt, something loose.....).

 

@Wendellnla
merged the 2 threads, as its all about that one EJ259

 

I had similar thoughts.
The oil analysis shows aluminum wear a bit higher normal, and iron wear much higher.
But no other metals like copper, lead, tin or nickel.

Aluminum could indicate piston wear which could explain piston slap. Not an uncommon thing on Subarus. But that doesn’t explain the excess iron

Or, could it be cam bore wear with worn out valve train components?

Or are main and rod bearing made from an aluminum overlay?
Which coupled with the excessive iron wear, could point to excessive rod and/or main bearing and journal wear.

Just trying to make sense of the info I have to make a decision on this engine.