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Numbchux

EJ251 in place of EJ25D.....IAC?

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So, As I mentioned in my thread in the new gen section, I just bought a '99 SUS with a mangled crank snout.

 

My coworker just parted out a '01 RS.

 

 

So, since the EJ25D is leaking like mad anyway, let's yank it out, and put in the 251.

 

Pulled the EJ25D last night, and noticed an oversight. Continued research today has me worried.

 

All EJ25Ds have the idle air solenoid mounted to the manifold next to the throttle body. And all EJ251s have it integrated into the throttle body.

 

Then came the thought, we'll just swap throttle bodies. Well, then we'll have nowhere to put the solenoid.

 

So, started researching swapping electrical connectors, and having the 25D ECU control the 251 stuff.....looks like the TPS would be fine, but the idle air, not so much. Looking at the pinouts, looks like the 25D has an Open and closed signal circuit coming from the ECU. Where the 251 just has one signal wire.

 

 

What are the odds, that I could hook up the Open signal wire from the 25D ECU to the lone signal wire on the 251 IAC, and have it work?

 

 

Plan B....Possible that a phase 1 EJ22 intake manifold would work? Gaskets are a different part number, but they look awefully similar.

Edited by Numbchux

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i may be wrong, but it seems that i read somewhere that the phase 2 ej22 and phase 2 ej25 intake gaskets were interchangable, if that is true then the phase 2 ej22 manifold would be an option

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Make manifold adaptor plates and use the 25D manifold.

 

Phase-I 2.2 manifold will not fit. Phase-II will since its the same as the 251 manifold but you run into the same issue with with IAC.

 

GD

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Make manifold adaptor plates and use the 25D manifold.

 

Jeez, that seems like a lot more work.

 

 

 

Yea, after staring at it for awhile, I think this is more work than it's worth. Also, I'm pretty sure the ECU pinout I found was for a phase II EJ22, which has a 3 wire IAC, but they're a different 3 wires than the older IAC (as mentioned above). But the EJ251 IAC is actually a 6-wire.

 

So, we're rebuilding an EJ25D, and going to clean up that crank snout. Off to the search feature to find out what the correct head gaskets are for that, I seem to remember that there was an updated part number or something.

Edited by Numbchux

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Jeez, that seems like a lot more work.

 

Not really - take a couple gaskets to someone that can water-jet you the plates. Then countersink some socket-heads to mount the plates to the head and bolt down your intake. Even with paying for the CAD and water-jet time it will be cheaper than rebuilding a 25D. I had some 25D to 22E plates made up to proto-type using the 25D manifold in place of the 22E - thus allowing any year and model of 22E to be used in place of the 25D - not just 95+ automatic's. The only reason I haven't yet done one is because I haven't taken the time to address the EGR tube. But a stainless flex or adding a small section to the factory steel tube will not be that hard.

 

So, we're rebuilding an EJ25D, and going to clean up that crank snout. Off to the search feature to find out what the correct head gaskets are for that, I seem to remember that there was an updated part number or something.

 

If you order from the dealer you will get the updated gaskets. They pulled all the old ones long ago and disposed of them. At any rate the life expectancy of a replacement 25D head gasket is no more than 100k and often times less. A fellow respected board member here recently mentioned to me that his 25D gaskets lasted about 80k after he had the block and heads surfaced, used Cometic head gaskets AND installed ARP head studs. Didn't matter -they still blew. It's a bad design and there's no solution out there that works. They WILL blow around 100k. Fact of life.

 

GD

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Well, this is a fix n flip car. I don't think intake manifold adapters are going to go over well for reselling...But I will remember that for future projects, as I'm sure I'll be encountering this again.

 

 

Also, I say "rebuild", but it's not a full rebuild. This car runs great, just leaks. So it'll be a Head gasket/reseal/timing belt job. It's already got close to 200k miles on it, and although the body is pretty rust-free for a midwest car, I would be impressed if the chassis holds up for another 100k miles.

 

 

Even with a full engine reseal, and a new fender/mirror, I'll have about $1500 into it, and blue book on it about $5k....

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What about the intake off a 99 forester or 2.5rs? They were a phase 2 EJ25 but still MAF so likely the same IAC logic as the EJ25d?

 

Nope. MAF logic but still phase-II IAC. Not compatible from a wiring perspective.

 

The ONLY good way to do this swap is with 25D->251 manifold adapters/spacers.

 

GD

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Or install the EJ25D heads onto the EJ251 short block and be done with it. Swapping short blocks would leave the car stock from a maintenance point of view.

 

You mentioned you didn't want to have to tell the new owner that there were special instructions to the engine if you repaired the crank...With the EJ251 they'll have to order a different timing belt, manifold parts, valves adjustment...and IAC, throttle body from something else maybe.

 

Not sure what the compression ratio would be but you're a smart cookie and can crank that out in no time to see if it's palatable.

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EJ251 is already in it's new home.....which is not this car.

 

 

 

I have a local feeler out for a good used crank, but we'll be ordering all the gaskets that we need to tonight or tomorrow, and hopefully have this thing ready for a new home by this time next week.

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Yea, bought this car with the plan of putting the 251 in it. Less than 12 hours after taking delivery, a good friend of mine (and owner of the shop where 2 of my cars live) blew up the 251 in his '01 Outback. So we had to make a quick decision.

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For future reference:

25D heads on a 251 block will make a nice running engine that WILL NOT blow head gaskets provided that the heads have been machined.

 

I'm running machined 25D heads on a 1995 22E block using thin MLS 222 gaskets & I've got 8K miles on it so far with no head gasket leaks.

 

If your mating surfaces are nicely machined, then there will be no gasket issues.

 

222s & 251 long blocks are compatible with each other & the cars they come out of but they aren't compatible with cars under 1999, which are Phase 1 EJs.

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K i know this is an old thread But for people that are in this situation i have the solution. I did a ej25d swap into a 99 OBS. i ran the ej25 off of the ej22 computer and it worked just fine everything worked out except my spark plugs and the IAC. so I rig up the spark plugs using parts off both engines. (needed the longer wires from the 2.2 and i need the ends from the 2.5) in the end they worked great. then came the sensor. I made an adapter plate for the sensor. it bolted on to the ej25d's intake mainfold and had a hole in the middle for the phase 2 IAC. mine worked out. not saying this is your best option but for me i had to get the car running. if i had the time i would have done an adapter plate for the intake manifold itself.

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