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Engine swap US to JDM EJ251 DIY head gaskets

67K views 50 replies 11 participants last post by  WelLRoundeDSquarE  
#1 ·
I am currently doing an EJ25 engine swap with a EJ20 JDM motor. I have a 2001 outback (170K) with a EJ25 SOHC engine that has a rod knock. Engine is out of car and on ground. Went down to LA and bought the JDM EJ20 engine yesterday, the vendor did a compression test for me and it was good.

I am now back at home and the intake is off and you can see into the valves and they are full of carbon, it looks pretty bad actually. I took off the valve covers and every thing looks nice and clean inside of it. When I look at my EJ25 heads they are pristine looking inside, very clean, not a sign of carbon build up and even the aluminum surfaces are clean. The 2001 EJ25 does not have EGR so the inside of the head looks great.

My question is should I swap heads and use the EJ25 heads on the JDM EJ25 short block? Is the EJ20 ok with that much carbon build up? The EJ20 heads have a multi layer gasket too, so no advantage to changing for that.
 

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#2 ·
could you review and edit your post: "My question is should I swap heads and use the EJ25 heads on the JDM EJ25 short block?" Maybe should be JDM EJ20 short block. (I don't know if there is one more instance of that EJ25 vs. EJ20)

and a FYI, if you just drop the EJ20 in as is. you will find it really SLOW and lacking, ...a complaint of our Aussie people here, as they had access to 3500lb cars with that engine.
 
#3 ·
You are correct, the question is there an advantage to putting the EJ25 heads with 170K on the EJ20 engine. Right now I am proceeding on with the EJ20 heads thinking I am being to anal and the carbon build and it won't hurt anything.

Is the EJ20 engine really that much of a dog in the outback? I created a thread about that subject and didn't get any answers back from anybody that had done one. I did find one article about the swap and the guy said it was a little slower but not bad.
 
#5 ·
I would think if you posted it in the Aussie / Kiwi section someone would have responded within a week. They got some in Europe too. Not to be confused with older 2.0 turbos that they sold too.

but depending upon the year the 2.0 naturally aspirated made 123hp or 137hp.

you might have to dig up acceleration times out of a Australian publication.
it maybe fine for around town driving, but given how others drive today it is not advisable to get caught in merging traffic with a car that you have to beat on for it to move.

My comment about merging traffic comes from a review of the first year Nissan Cube as tested in LA. The sentiment was it was OK to drive, but you have to be running the stick shift and working the gas hard just to do what other people are doing with all other cars on the road with little effort.

___________

I don't know why they even import those little 2.0 naturally aspirated ones to the US, how many cheap dune buggy engines do you need?

the carbon in your pic worries me, just as a person not as a expert, but it is like these things were cheap turds that they made for little subarus to poke around Japan in traffic and on the flat.

And if you go without a EGR like some of the JDM engines seem to lack, you will be stuck with a check engine light as the USDM ecu is looking for something that is not there. (I guess you live in California, and like NYS where I live, I guess you don't pass annual inspection with a check engine light.) Plug and play it is not. (edit: whoops 2000-2002 US spec legacy / legacy outback, no EGR....2003-2004 legacy / legacy outback has EGR).


you could not find a USDM EJ251 to drop in, out of a rear end wreck, just after its head gaskets got done?
 
#6 ·
All the used engines that I have been able to find go for around $1600 and they all have 150K mi. What scares me is the engine i had 170K so I really have no faith in a used engine with close to the same amount of miles.

I was hoping the EJ20 would not be that bad performance wise and after hearing your comment and the shape the engine is in I am going to take it back. I can get a rebuilt long block for $1600 or I can get a JDM EJ25 for $1600 and both of them were on the shop floor Friday when I was there. I am nervous about the rebuilds since I don't know who does them so I think I will try the JDM EJ25.

The comment on getting a trouble light for not having a EGR is not true in this case. My 2001 USDM 2.5 SOHC does not have a EGR and that is why I believe the intake and exhaust were so clean. When I took it apart the throttle body, intake manifold and valves were very very clean. The JDM's EJ20 doesn't have an EGR either and that is why the gummed up carbon coated valves are suspicious. That engine looked like it was used and abused. The crankcase front seal was leaking and the rear cover was leaking oil too. They said the JDM engines are suppose to have an average of 35K mi on it and I don't' buy it in this case.

I talked to the the company I bought the JDM EJ20 from and I can exchange it but I cannot get my money back. I have decided to pack it all up and exchange it. I will either get a rebuilt long block or the JDM EJ25 they had. It's going to cost more but in the end it will be better. This whole project is really turning into a giant pain in the rear. I am wondering now if I should have just rebuilt the thing myself.

I can say one thing for sure and that is it everything after the intake manifold sure looked like a plug and play. All the sensors were the same, all the PVC and manifold hoses off the block were the same, the timing cover, the OHC gear, the crank gear and washer, all of looked identical.

More to come after I exchange the engine.
 
#7 ·
what if the person that had the EJ20 did not change the oil or just added it.

what if it was a Aussie engine that was run from sydney to perth and back weekly.

happy it was plug and play, not enough people trying what you are doing there to read about at least in outbacks / legacys. I would think there are a whole lot of 2000 and newer EJ25 Imprezas out there with EJ20 in them though.

and of course the bugeye impreza RS people LOVE the JDM imported turbo engines,...as they have lighter cars then the more modern WRX and get a engine just as powerful or even more so.

I wonder if you can open the a JDM EJ25 and look at it for carbon before driving it home.

which engine importer shop is this?

If you want to cost compare or ask questions to real experts with real good rebuilt crate engines. (big bucks, but good)

Edit: below the link for CCR

EJ25 2.5L SOHC
 
#8 ·
00-04 EJ25x are speed density, (meaning they have no mass airflow sensor, fuel metering is done as a function of air density (manifold absolute pressure + intake air temp) and engine speed (RPM).

The EJ25 will pump more air than an EJ20. . .so if you run the EJ25 ECU, you will run rich as the ECU will be sending enough fuel to match the amount of air an EJ25 would be drawing in.

It would probably run Ok tho but I would expect fuel mileage to be kinda crap, and I'd be unsure of the long-term viability of that setup without some form of correction.

Just posting to reinforce your decision to stick with the EJ25.
 
#9 ·
if you favor reliability - keep the EJ20.

JDM = lots of city time and carbon build up probably from idling or possibly other issues. i'd probably just run it and let issues come as they may since there's a good chance they won't.

if you favor performance and don't mind the expense/time of replacing the headgasket down the road - get the EJ25.

if you have a manual transmisison the lack of power is easier to absorb/not notice.

i removed an EJ25 and swapped in an EJ18, in an automatic. it's a great engine - they'll run forever and if properly maintained you can almost expect 300,000 miles out of them with little repair costs. same with the EJ20 and EJ22.

as to the EJ18:

it's fantastic in flatland - excellent gas mileage and drives just fine.

it is weak. with 16" wheels/tires and a full load of 5 adults it can't hold 70 mph up the steepest interstate grades in the mountains. i keep 15" wheels and smaller tires on it.

but - the reliability and ease of maintenance over the past many years/miles - can't beat it, that's exactly why i did it. i don't hardly have to thin kabout that car..."have i changed the oil in that thing any time recently?"
 
#10 ·
What EJ20 is it? What did it come out of? There are lots and lots of EJ20 motors, and they are all vastly different from each other.

Same with the EJ25.. there are many different versions of that engine as well. Your 2001 Outback came with an EJ251 or possibly an EJ253. An EJ202 would probably be the most similar EJ20x engine, and would largely just need an ECU swap and possibly some wiring mods.
 
#11 ·
Ok I got the JDM 2.5 engine. It a 2002 to 2004 year model. Its a EJ25 block and Z25 heads. It has EGR but I can plug the port so no big deal. The engine is in a lot better shape than the other one I got, you can tell it has less miles. It is way cleaner. I will be moving lots of parts from the original over to this JDM engine. Things that are different are the coolant cross over pipe, head has EGR port, knock sensor, and crank front timing gear

Do you think I should change the the head gaskets out while I have the engine out. I wasn't originally planning to do that but seems like I am doing everything else. They ones that are installed look like they are a single layer gasket. I know six star is a recommend brand but are there any others, are the fell-pro or Victor Rienz ok to use? I was thinking I would just remove the head check flatness and then reinstall.
 
#12 ·
Yes you got a JDM with the same crappy head gaskets like the USDM.

its out. buy Fel Pro, or Six Star, both good, (edit: in later dates, I have read that subaru turbo OEM gaskets with bare MLS are the only way to fly).

SKIP Rienz.

How many miles on it,...just as dirty inside as the other one? I would think that based on the USDM EJ251 that the heads and the block remain basically straight but typically people clean them up / and or do quick MILD hand resurfacing.

Gates timing belt kit,

OEM PCV, OEM thermostat. = the OEM on these is cheap and it avoids unreliable crap. Subaru Water pumps are pretty reliable or so they say here, so you might get one off the old engine if you don't got one with the new.
 
#13 ·
If you pull the heads, you've gotta machine them. . . mind you there are folks here who are advocates of the 'post apocalypse home head resurfacing technique' involving spray glue, sandpaper, and an ultra flat rigid surface (glass or a chunk of granite countertop) and I can't endorse or refute it so if you don't feel like paying the $150 or so a machine shop will charge you to flatten them out, that's an option.

As for gaskets, I use the OEM Subaru 610 turbo gaskets (thus named because the part no. ends in 610). They're awesome.
 
#14 ·
If you pull the heads, you've gotta machine them. . . mind you there are folks here who are advocates of the 'post apocalypse home head resurfacing technique' involving spray glue, sandpaper, and an ultra flat rigid surface (glass or a chunk of granite countertop) and I can't endorse or refute it so if you don't feel like paying the $150 or so a machine shop will charge you to flatten them out, that's an option.

As for gaskets, I use the OEM Subaru 610 turbo gaskets (thus named because the part no. ends in 610). They're awesome.
I thought we were there already:

edit: here is that USMB thread
http://www.subaruoutback.org/forums...orums/110-gen-2-2000-2004/165417-engine-swap-us-jdm-ej251-diy-head-gaskets.html

Image
 
#15 ·
So it was a bad week at work but I am back to working on the car again. I have already swapped the JDM EF20 for a JDM EJ25 casting with Z25 901 and 902 cast into the block and Z25 heads. I was told it was a 2003 to 2005 model.

The crank gear and cam gear are different than mine so I was going to swap them out. Does anybody foresee a problem with that. I have to do the cam gear also. I included a picture of the 2 different crank gears. The Z25 is on the left.

I am going to pull the heads and change out the gaskets. I found a granite surface plate at work and am going to try to wet sand the heads flat on that using the the old school method. I will let you how that goes.
 

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#17 ·
I have read so many articles about the head gaskets failing that I thought it best to change them out while I have the engine out. The car is going to my son who is going several states away to college and I need to make sure the car will no mechanical issue.

I just got done taking the first head off and the pistons had a bunch of gunk in them. Good new it was real easy to clean out and now both of them look spotless.

I did a water test on the valves and all of them are leaking, both exhaust and intake. I guess I am going to take off the cam out and then pull the valves and hand lap them.
 
#18 ·
I notice how wise Canubaru has 3 cars with wonderful trouble free engines in them
01 Outback H6 VDC,
97 GT wgn w/ ej22, 98 OBW w/ej22 (these are divorced of their EJ25D turds)

now the EJ25 SOHC is not a turd, but even the JDM has the crap gaskets in them,...and it is going to fail sooner or later. (and I wonder if the way the JDM's actually are I would think doing head gaskets on all of them is a good idea.)...

I can see the logic of "if it ain't broke don't bother fixing it, yet" but at the same time, plenty of crate engines have them done, or expect the new owner to do them. (the JDM sales people may not "make" you do it, because they are willing to say anything to make a sale,
and happy if you come back with a HG problem in a month, because they have 20 more stacked up like the one you just got and are willing to give you another one, for the junk one you got now).

Kite: where is your kid going to school, ...it maybe a cool thought to keep in the back of your head that when he is getting done with school that he / you sell the car there. If it is somewhere where subarus are in demand like colorado or where they rust, you could get all your money / and aggravation money out of this in the end.
= Listing it as california car, head gaskets done, :cool: x :cool:
and on its way towards 300,000 miles. one forum member out of Iowa, whenever he goes to california he buys a subaru unrusted with minor problems and pays to 18-wheeler it to iowa, fixes it up and sells it, which pays for the trip and then some.
 
#19 ·
I guess what I am looking for from forum readers is if any body see something wrong with what I am doing please let me know.

I have pulled the heads and checked them for flatness using a straight edge. They look flat to me, I have some .002" feeler gauges coming to check officially but it looks good, no gap at all.

The pistons were full of gunk so I cleaned them and they look almost like new. I used carb cleaner and a tooth brush to clean them. if you look at the center there are a bunch of what looks like little marks, any idea what those are from?

I did a water test on the heads and the majority of them leaked so I took the rocker panel over the cam off and started removing the valves. After I get them all cleaned up I plan to hand lap them in. Is there anything that can bite me with this plan? it all seems pretty simple and that's what scares me.

I have attached several pictures of what I have done so far
 

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#20 ·
So I am concerned about lapping the exhaust valves. They are suppose to have a nitrite coating so I don't think I am suppose to lap them. If that is the case then what should I do.

Am I suppose to cut the valve seat somehow using a tool? Should I sacrifice one valve to lap all the seats and then replace the one exhaust valve with a new one? Should I just put it back together and not do anything with the exhaust valve.

The intake valves should be ok to lap correct?
 
#21 ·
So I don't know what to do. I tore one head torn down and cleaned it all up and put it back together again.

When i do the water test I maybe get a little weepage but when I blow air to the piston side of the valves I see air bubbles in the water. I called the nearest machine shop I trust and they said that lapping will do nothing because the valves expand when they get hot. he quoted me $200 a head to grind them all. I really don't want to spend another $400 on this project.

Any ideas on what to do? Leave them alone (do nothing) or lap them anyway because that is what the manual says to do.
 
#22 ·
I usually don't do a valve grind unless the pre-teardown compression test sucked, and then I'd have a good look at the pistons and rings and decide if the short block was hosed.

Price sounds about right. My machinist does them for $9/valve, not including resurfacing which is $75/head. . . so about $300/pr. for milling and a valve grind, but I'm in the cheap seats as far as cost of living goes and this is a guy I've been using for 20 years. I pay cash, no receipt, and I don't pester him. Drop 'em off, he calls when they're done.
 
#23 ·
so is your recommendation to do nothing? Is the little bit of leaking I have not going to affect anything?

I am leaning towards lapping at least one of them, what can it hurt? Maybe it will make it seat better. The machinst I talked to said lapping should have went away with the model A and it would do no good so he made me feel like it was the wrong thing to do.

I sanded my head on a surface table with a piece of sand paper glued to it.....Seems like it came out pretty good....I can't get a .05MM feeler gauge under the straight edge I have. I will attach some pics of how I did it later.....it was pretty flat to start so it went ok.
 
#25 ·
So I just got done lapping one of the exhaust valves. The seats were kind if shinny and had some pits or stains or something and now the surface is a dull looking color and all the pits are gone. There was not a lot of pits or whatever they were but now they are all gone. The valve was the same way but on it you can still see a little bit of the remnants of the pits. I can't get good close up pictures but I attached one of the exhaust valve from a little distance away.

I'll bet it will pass the water test now.

Should I keep going and do them all?
 

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#26 ·
you've gone this far - do it and be done with it. good job with the valves!

1. water causes rust. filling the intakes and looking for rust gives valves, stems, and valve stem seals opportunities to oxidize. be careful.

2. This is pure speculation but I wouldn't worry too much about water leakage. that engine was likely running amazingly right before it was pulled. it may be that many 100k engines "leak" under a test like that, that's just a suggestion though i'm not certain of it. when engines are turning at thousands of RPM's and pistons are containing the pressures and forces of explosive materials...the difference between your heads before and after are probably nearly negligible in terms of engine performance. i've done this test before too - but not very often - it'd be interesting to do it on a few/dozen sets of good heads and see how many "leak".

3. "grind" them as essentially a clean up procedure and install them. sounds like you're doing perfect.

4. Resurface the heads yourself. Yes you have to source a proper machinist grade granite or 3/8" or thicker glass (not tempered, just regular glass)- but the glass is easy and available locally anywhere.

DIY Head Resurfacing... or "Post-apocalyptic machine shop techniques!" - Old Gen.: 80's GL/DL/XT/Loyales... - Ultimate Subaru Message Board

Even if they are without issue, I have yet to resurface a Subaru head that didn't show high/low spots during the resurface procedure. Given that and their propensity to have head gasket issues, i wouldn't skip that step, there's no reason to on such a big job.

There is hardly anyone that can talk technical/materials properties as they pertain to automotive mechanics like GD can. His experience and capacity are top notch. All that to say - it's a bit non-standard but follow the directions and you're golden.

Once you get the piece of glass - it takes like 11 minutes, I'd rather just have a shop to it and clean the heads for me but it saves so much time - not dropping off, waiting, going back, there are no places close to me.

*** Don't forget the Subaru coolant conditioner when you're done!
 
#27 ·
I have already done one head....I used a small surface table and glued the sand paper to it like just like the post. I used 400 and then finished with 1200. According to that site you attached the guy said the highest you should use is 325 grit so you don't get it too smooth. I finished with 1200 but honestly I don't think it is too smooth. I can redo it with 400 grit again if needed. Sometimes that my problem, more isn't always better.

The head barely fits on the 11" wide surface table but it was fine. I did not have any trouble sanding it down. When I measured it before sanding I could not get the .05MM feeler gauge under it but after a little sanding with the head all lubed up I was able to get the .05MM FG under it on the diagonal test. So the lesson here was to put some lube on the head before checking the flatness and you might find what you thought was good dry is not when lubed or oiled up. I did not use WD40 either since I did not have any on hand. I used fluid film (lanolin) and it was fine.
 

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#28 ·
Yes, use WD40 or something similar.

I used a small surface table
Woah, is that machinist grade granite or glass? This needs to be thousandths of an inch tolerance.

You need something that is inherently flat - the production mechanics of glass ensure high grade flatness. nothing else does. i would cringe at using a random table.

I would resurface with 400 grit using glass or machinist grade granite.
It's better to not resurface than to use materials that don't have thousandths of an inch tolerance associated with it.

I guess you can keep checking but I'd expect non-flat sections to just "move" from one place to another as you try to address them on a table that's not properly spec'd. the fact that it was worse after doing it - probably suggests the table isn't properly flat.

Hopefully I'm just assuming incorrectly since you didn't explicitly say what it was - but I wanted to get it clear in case I didn't see this thread later.

ANY local glass shop will have glass to properly do this. Or use a glass cabinet door or screen door insert, old window...all properly braced so it's not bowing...something at least is better than nothing?

Also do circular motions, figure 8 style, not back and forth.
 
#29 ·
. . .or just pay the $150 to a machine shop and be done with it.

What's your time worth? What's it worth to you to ensure you won't have to pull those heads off again and buy another $100 worth of gaskets?
 
#30 ·
kitesurfer, I just wanted to let you know I Private messaged both gary and the lockmedic to look at this thread, ...as they both actually have done this kind of work many times.

(I think both sleep with a pistol and a expensive torque wrench under their pillow).

ultimate how yours comes out will help others trying the JDM alternative,...and I already linked it to someone working on his girlfriend's 2001 EJ25 SOHC.

good pics. / and good luck.