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2006 EJ25 doch head swap for 2005 EJ25 soch


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51 replies to this topic

#1 naldo

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Posted 16 April 2013 - 07:05 PM

hello people i was just wondering is it possible to swap the heads of a 2006 EJ25 doch  to a 2005 EJ25 soch heads i do have both intake manifold and the wiring harness. will they fit alright or no . the computer on my forester is currently running a soch ecu    I am trying to do this because i bought the motor doch and didnt realize that the wiring harness is totally different from my soch ecu that i have



#2 grossgary

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Posted 17 April 2013 - 06:14 AM

There were no DOHC's after 99 in the US market so you'll need to tell us what engine it is...is it JDM or is that a typo or....

 

If it's JDM variant then you should be able to bolt your existing intake manifold onto the new motor.  Now is the time for a new timing belt kit as well, regardless of mileage it's 8 years old.  If the vehicle had EGR and the JDM engine does not, you will have a check engine light or need to do some retrofitting to work around that....swap heads, custom piping...something.

 

In the US market - DOHC and SOHC intake manifolds are not interchangeable and the idle air control is different, they're annoying and essentially not swappable without significant effort and check engine lights.


Edited by grossgary, 17 April 2013 - 06:14 AM.


#3 bratman18

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Posted 17 April 2013 - 07:42 AM

The only dohc in that year was a turbo model. The last n/a dohc was made in 99.

#4 naldo

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Posted 17 April 2013 - 07:53 PM

well i bought this motor from JDM straight from japan and they told me it was 2000+ year model they specified that it was a 2006 model i don't know if they were correct on that .. I currently had a 2005 EJ25 SOCH on the car the motor went bad that's why i want to use the heads because i don't got that much money to spend on a ecu and complete wiring for the the DOCH so I was thinking in making my DOCH block to a SOCH somebody told me that they were interchangeable since they were the same Block I wasn't sure about that if it was possible



#5 86BRATMAN

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Posted 17 April 2013 - 07:59 PM

could you possibly upload some pictures of the engine, specifically the valve covers, intake manifold, and the intake manifold bolt pattern to the heads, among other thing this would help identify the engine

#6 naldo

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Posted 17 April 2013 - 08:09 PM

how do i upload picture because i am new at this ?



#7 naldo

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Posted 17 April 2013 - 08:18 PM

these the motor that i received 

Attached Files



#8 86BRATMAN

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Posted 17 April 2013 - 08:33 PM

did you get this one off their ebay site, I saw one on there a few days back and it looked like the same pics, it boggled me, because it has the phase 2 iacv on the throttle body and dohc

#9 grossgary

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Posted 18 April 2013 - 01:46 AM

to swap heads, i would aim to bolt your heads to that block - which is I think what you're asking.  when you do that, use the EJ25 Turbo headgaskets simply for the fact that they don't have headgasket issues like the nonturbo headgaskets.

 

be sure to resurface the heads.  there's no need to pressure check or test them, the non-turbo heads are never out of spec, you can do it yourself, it's really easy:

http://www.ultimates...hop-techniques/

 

I would attempt to swap the SOHC intake manifold onto the DOHC engine. the DOHC has variable valve timing heads but will run fine, the SOHC just won't control or use that system.

 

that being said...what happened to the original engine?



#10 lmdew

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Posted 18 April 2013 - 05:26 AM

If you ordered a SOHC, I'd make them send you the correct motor!



#11 naldo

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Posted 18 April 2013 - 03:48 PM

ooh ok so i bought this motor ought of a website online... 

 

And  the original motor have a bent piston I think i just going to take the SOCH head to the machine shop before putting them on just so they don't give me any trouble 

 

the problem with the original engine was that the head gasket failed and leaked water to the pistons and you know what happen next so yeah ..

 

the only reason i bought this motor because apparently my mechanic told me that it will work and it doesn't work at all so IDK what kind of mechanic he is lol apparently not a good one.

 

 

Ok so i need a head gasket from a turbo one should i get the DOCH turbo head gasket or SOCH turbo head gasket?



#12 grossgary

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Posted 18 April 2013 - 04:28 PM

This same swap (DOHC JDM into SOHC EJ25) has been done before without swapping heads, so you're mechanic may not be entirely wrong.
Why not bolt your intake manifold to the new engine?

 

 04 WRX STi headgasket Subaru part # 11044AA642



#13 naldo

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Posted 18 April 2013 - 05:55 PM

the only problem is that my computer and cables that come out to the car to the motor bay are for a SOCH engine so my intake has the wiring harness from a SOCH 

 

The ones that came with the motor have different wiring harness because it doesn't contain the plugs for the electrical throttle body

 

 

The are 2 cam sensors and another two on the heads of the DOCH that the wiring harness for my SOCH don't have 

 

 

the Subaru is selling me the wiring harness for the DOCH with electric throttle body which is the one that i need for $260 bucks if I were to putting right in without changing my heads   and it plugs in into the original cables that come out of the SOCH computer  but

 

Would the SOCH computer run my DOCH if the wirring harness are change to the one that i need? 



#14 grossgary

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Posted 18 April 2013 - 07:29 PM

the only problem is that my computer and cables that come out to the car to the motor bay are for a SOCH engine so my intake has the wiring harness from a SOCH 

 

The ones that came with the motor have different wiring harness because it doesn't contain the plugs for the electrical throttle body

 

 

The are 2 cam sensors and another two on the heads of the DOCH that the wiring harness for my SOCH don't have 

 

 

the Subaru is selling me the wiring harness for the DOCH with electric throttle body which is the one that i need for $260 bucks if I were to putting right in without changing my heads   and it plugs in into the original cables that come out of the SOCH computer  but

 

Would the SOCH computer run my DOCH if the wirring harness are change to the one that i need? 

 

you're not hearing or listening..it's hard to explain when we only get to type. 

the wiring and plugs are completely irrelevant for now:  bolt the SOHC intake manifold onto the DOHC engine block - then it has the same original wiring harness and the ECu doesn't know any different.

 

the extra cam sensors are for the variable timing stuff and not necessary, so just don't use them.  that's done on USDM swaps so i assume same with JDM...

 

so:  make sure the intakes have the same bolt pattern and interchange - bolt spacing, etc. they're probably the same.

make sure the cam sensor you need (drivers side top  same location as original engine) is in place and the same - same connector..if not, just swap the sensor.

 

anyway...i think it would work without any additional expense or much effort.



#15 naldo

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Posted 18 April 2013 - 09:43 PM

ooh okay i will try that this weekend thanks alot i will keep you guys updated with the info of what happend 

 

thanks 



#16 grossgary

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Posted 18 April 2013 - 10:31 PM

i hope that makes sense - there are like 4 bolts on each side of the intake manifold that hold it to the heads - so 8 total bolts.

then of course remove hoses, disconnect wires, sensors, throttle cables, etc and lift the entire intake manifold as an assembly off the engine.

install the other one.



#17 naldo

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Posted 21 April 2013 - 04:25 PM

OK so i manage to plug everything the only problem that i encounter was that my spark plug wire are too short  one of the wire doesn't reach the coil distributor .

 

do you guys know if they sell longer cables for that type of covers. If you can see on the picture that i posted the spark plugs top are different they are not round so i need to find those same one but longer. Does anybody know if they sell them longer ?



#18 grossgary

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Posted 21 April 2013 - 08:30 PM

can you simply remount the coil like it originally was for that engine/spark plug wire set?  that's what i'd do so it keeps things simple now and for future spark plug wires.

 

a company like Magnecor can probably make you a set longer...or tell you their lengths - they may be slightly longer than stock anyway.  can put like 200,000 miles on their wires too - for $60 you can't go wrong, i run them on like 3 vehicles for years and get tons of miles out of them.


Edited by grossgary, 21 April 2013 - 08:30 PM.


#19 naldo

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Posted 22 April 2013 - 12:05 PM

And they make the ones that I need correct I will check that out you said Magnecor right okay because I was planing to buy a universal ones but they don't come with the same cap for the cover of the DOCH motor

#20 grossgary

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Posted 23 April 2013 - 06:08 AM

what about simply relocating the coil?

 

i wouldn't get universals anyway - they're usually cheap and EJ engines are prone to cylinder misfires with cheap wires, they'll do it right out of the box.

 

magnecor likely won't have what you need but can make what you need if you give them the ends and lengths required.

 

the problem i see here is every time you need a spark plug wire change you'll be in trouble again...at least with the Magnecors you'll never have to replace them, they'll last the life of the engine.



#21 naldo

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Posted 23 April 2013 - 09:50 AM

i think i am going to get a magnecors wires because i try to relocate the wires already and didn't work and it just one spark plug wire that is falling short to the distributer i am going to call them to see if they can make me the same ones that i have but longer

 

I let you know what happens XD



#22 naldo

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Posted 25 April 2013 - 11:01 AM

so i have a problem   my spark plugs are not getting fire i check the able that goes to the ignition coil N is getting electricity but from the coil out is not firing what  you guys think   might be i already bought a ignition coil  just in case it  bad if thats not the problem what you guys think it might be



#23 grossgary

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Posted 25 April 2013 - 05:45 PM

any check engine light/code - have you read the code yet?

all sensors plugged in - cam and crank?

igniter plugged in and working?

 

some EJ engines around the 2001 era have different cam sprockets and you have to switch them to get it to fire correctly.  the trigger marks are different.  compare the trigger marks on back side of the cam associated with the cam sensor on the new engine to that of the old engine.  shouldn't be that though, there is another guy that stopped one of these DOHC JDM engines in his and it ran.....


Edited by grossgary, 25 April 2013 - 05:46 PM.


#24 naldo

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Posted 26 April 2013 - 10:25 AM

All the cam and crank sensor are connected at least the two that are in front of the motor. igniter plugged is in and working but for some reason my ignition coil is not firing .

 

I bought a new ignition coil just in case that one was bad . 

 

i do have the cam and crank sensor from the other motor do i switch them or not? . I don't think it will make a difference because my plugs fitted right in  the other ones 



#25 grossgary

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Posted 26 April 2013 - 10:30 AM

sensors probably won't matter as you suspect.

 

you need to count and compare the trigger marks on the back of the cam sprockets...unless you run into some other thing to check.






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