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2001 Engine vs 2003 Engine

1034 Views 29 Replies 6 Participants Last post by  cgeromi
I have the opportunity to take my dad's engine out of his 01 Outback and swap it into my 03 Outback. Ill spare everyone the reasons why, that's a long story!!

I know my engine is stamped ej25. I also know that my 03 has a map sensor and my dad's 01 has a maf sensor. Other than that, everything else is the exact same.

Could I take his motor and put it right into mine if I use my existing intake or would I need to swap anything else out?
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Yes to using your intake and harness. Check the driver side cam gear and crank reluctors. I don't think there's a difference for the cam and crank sensors, but it's been a while and can't recall.
What do you mean by the crank reluctors?
The teeth on the crank and the bank 2 cam gears that trigger the sensors.
Oh ok. I'll have to do an in-depth comparison of my dad's 01 to my 03 motor components. My 03 motor has rod noise around 3000 rpms and the car has hdit been a nightmare since I bought it last January. My dad's Outback on the other hand has been old reliable! She's rotted but her power train works well.

Wonder why his motor has a maf and mine has a map sensor? Any idea what motor code came in his 01?
The '03 will have EGR, the '01 won't (at least for non-CA cars). This compicates it a bit if you have to pass emission inspections because the '03 computer is looking for EGR input. No EGR and you'll get a CEL code (engine light). The '01 driver's side head (assuming US car) will not have the port drilled out and threaded to accept the EGR pipe that goes from there up to intake manifold (which is different on '03, beacuse of EGR). The head can be drilled and tapped to fit the EGR pipe (I've done it in this situation).
Well that's a bummer! My county doesn't have emissions inspections/tests but I hate having a cel. I'm going to look at my car (03) tonight and look at the EGR system. I never really took notice of it.
The crankcase ventilation valves are different between the 2.
What would I need to do to use his motor with this difference?
Don't remember at the moment - it was 3-4r years ago that I found that there was a difference (I have both an '01 and an '03, and bought 2 of the '01 versions before I found that there was a difference). Sorry!
No problem. I'm going compare the 01 vs the 03 here this evening. I'll reply back with some pics.
Ok so just parked both cars side by side and did a comparison.

  • Both cars are ej251
  • 03 does in fact have EGR components as shown in pics below
  • I would have to block off the EGR if I swapped in the 01 engine. Any suggestions what I could block it with, with minimal effort?
  • 01 has a different crank system. The 01 goes from the block into the throttle body and also into the air box. Where it splits there is a plastic piece that's round. I'm thinking a carbon filter.
  • My 03 crank system goes right from the block and into the throttle body via a thinner rubber hose than the 01
  • Transmission codes are different but both are different. The 01 has engine has a more square projecting piece on the engine where the end of the block meets the bell housing. See pics below.
03 EGR setup:
Motor vehicle Automotive tire Automotive fuel system Gas Automotive wheel system

Gas Motor vehicle Auto part Automotive exterior Metal

03 Transmission (where engine meets bell housing):
Automotive tire Motor vehicle Gas Automotive exterior Auto part

01 Transmission (where engine meets bell housing):
Black Automotive tire Gesture Style Motor vehicle
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What you are referring to as Crank is the PCV system. These can be swapped.

The "crank" concern is if you have the same crank and cam trigger systems on both engines. This is the go-no-go.
Can you be more specific about the same crank and cam trigger? From what I can see the 01 and 03 cam and crank sensors seem identical.

As for swapping the pcv parts, the 01 uses a larger diameter tube and my 03 is smaller. If I use my dad's 01 engine and my 03 intake, the pcv tube as the motor is large diameter and smaller where it would go into the throttle body.
if this is pennsylvaina that rust "needs" some bondo. 💪
Definitely Pa penn dot rot. Compliments of the state. The 01 motor runs incredible! I wanna make this swap work but the pcv system has me a little perplexed how to make it work.
Here's the pcv systems...

03 pcv at motor:
Footwear Shoe Leg Human body Automotive tire

01 where pcv at motor:
Automotive tire Grey Fender Hood Automotive design

Shoe White Tire Automotive tire Black
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oh, and what is wrong with the 2003's OEM engine, its OK to state it ran out of coolant / out of oil.
(the subaru oil trouble light comes on right when the engine is going terminal, not actually a low pressure warning light)
It's a LONG story but i'll "try" to keep it short.

I bought the 03 back in January of 2022. Bought it from a guy who has a little shop that buys broken subi's and fixes them and sells them. He seemed to be a nice family guy just trying to make some extra money on the side. The seller said he bought the car from a lady down the road who lost her crank pulley and blew the top end of the motor. The seller rebuilt the heads and installed a bunch of new parts. He gave me records and the car seemed like a great buy!!

Then pretty much from the day I drove it home I had problems with it. Just little things. New thermostat sticking, brakes sticking. etc. Also, the car from day 1 ran so rich it smelled like a friggin lawn mower! From Jan 22 to August I drove the car here and there and even though it ran rich with poor gas mileage it still seemed to be solid. Fast fwd to August 22. I was preparing to take the wife and kid to OBX. I slapped on a big old turtle on top of the roof rack, changed all the coolant hoses, rotated the tires, and gave her the 100 point inspection. She was READY! I told the wife a few day before the trip, let's take her a test run down route 80 to pick up our son from his grandparents about an hour away. After about a 40 min drive on route 80, I got off an exit, coasted down a hill and the car just died. The motor just stopped. I had the car towed to a mechanic friend of many years and it was determined the timing belt with 4000 miles had failed!! I went back in the my records from the seller and found the timing kit. He bought a Chinese kit on Amazon. 4000 miles!!! That's all it would get me.

So, a buddy of mine said tow the car to me and let's take off the heads, take them to a machine shop and put on new heads gaskets. So, we did just that. $1000 later in head work and all new seals, gaskets, Aisin timing kit, the car was ready to crank. We cranked her over and it ran like dog poop! I then had the car towed to very reputable independent subi shop my dad has worked with for many years. They determined the valves were too tight and the MAP sensor and o2 sensor were bad. After a few days the shop called me and said I have good news and bad news.

The bad news:
The engine has bottom end knocking after 3200 rpms. Which after he said that I realized that I heard it all the while since I bought the car I just attributed it to the terrible sound the boxer engine makes :)

The good news:
The car now runs from a fuel and air standpoint amazing! Fuel trims are darn near zero and my gas mileage is right on spec.

So I pay the pauper and bring the car home and after driving it home in Dec of 22, I notice my coolant temps wont go below 203 and the fans are constantly running. I install a brand new t-stat (once again) and rad cap and do a flush. No go. The car still won't open the thermostat. After much research I determined something my friend and I did during the head gasket installation must be incorrect. I am bringing in combustion gas into the coolant system and it's back up at the t-stat. So since Dec 22 I drilled a hole in my t-stat and have put about 1100 miles on it. But, I can only drive it locally and with it being winter it won't overheat.

At this point I'm at my wits end and my dads 01 Outback is rotting away and he offered me his motor because he got a newer car.
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the good news: PA and not southern california. so finding 20 year old subaru engines in great shape maybe cheap / painless. and not maddening.

(just like when the 1st guy had it, ...the right thing to do if starting up a subaru fix it business: specialize in the things you are buying, so you can always have the exact matching part in your own pick/pull.
so it would have been nice if he had a great supply of Legacy / outbacks in both 2000-2002, and 2003-2004 varieties).

a while back I was picking up a truck at a auction, and there was a guy with California plates on his 18 wheeler. he was loading 10 rust bucket fords on, all 5.4 engines.
all with NY rust that could choke a pig, and all going to southern califrornia. to sit behind a truck garage and be parted into rust free things.
...and the truck driver said, today its 5.4 fords from around 2004 , next month 6.6 chevy diesels circa someone out there loves North East Rust.
My big issue right now is I have $5000 into this thing. $3000 purchase price. $1000 to do the heads and parts. $900 after I took it to the independent subi shop. I'm either putting in my dad's free motor or I'm running this current motor into the Susquehanna river!! 🤣
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I would make arrangements to have that EGR tapped out of your dad's engine. (ask a couple engine shops).

and you are not the only one who has spent $6000+ on what was thought to be a $3000 all in purchase.:geek:
I was going to plug my current 03 intake with a 3/4 plug and delete the egr stuff...
If they are both auto tranny, there shold be no issue swapping in the 2001 engine. I swapped a 2003 2.5 L engine from an '03 Forester into a 2001 OB, both were automatics and no issues. The EGR thing is your choice; you can either have the head drilled to accept the EGR pipe or cut the pipe off and have a welder weld up the cut end (so it acts like a plug) or take the EGR pipe and find a plug that matches the thread on pipe (that goes to EGR). I think you could even leave the EGR port unplugged and just disconnect the connector (so EGR valve won't open). But this would give you an engine CEL (light) for EGR malfuction for sure. I can't remember what I did for the PCV hookup but I'm sure it wasn't that difficult. Depending on where you live, it could be a struggle to get the engine and trans separated. In the salted north east, the dowel pins tend to get stuck, making it a chore to get engine to separate from tranny (there are threads on this). Also, be very careful not to let the torque converter pull out of the tranny. If it does, you need to be very careful reinstalling it (search is your friend here too).
Thanks Mike! I'll be doing the swap probably sometime in April or May. I think to make the pcv work, all I need is a reducer, or I could just install a catch can and plug up the whole on the throttle body to stop the vacuum leak. I'm pretty excited, his motor runs impeccable! I'll pretty much have the entire 01 Outback at my disposal, then I will put my half broken motor into his 01 and sell the 01 for whatever I can get for it.
did you consider putting the 2001 trans in the 2003 ?

leaving it coupled with the engine. you may need a extra set of hands, = subaru engines with trans make for a long thing on the crane, but a time saver and less fustrating if you can just leave them coupled.
No. His transmission has 313,000 miles on it. Mine has 192,000 miles. HIs motor only has 190,000 on it though, which is why I want his motor.
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