subaru FB25 engine interchange

In reply to jdf60 :

I looked at the 2016 Legacy shop manual and the TGV system seems to be more tightly coordinated with the throttle and operated in PWM servo mode rather than bang open/closed like before. Needs more study but I will see what I can infer about the hardware from the diagnostic graphs etc. Almost everything seems to be done using the Subaru Select Monitor which I believe is what they call their scan tool. No more resistors and multimeters.

Edit

Looking at pictures, the 2013-2014 Legacy TGV actuators are the same Denso part# 012010-6110 as jdf60 received on the 2015 Legacy engine. Given that the 2013-2014 Legacy engines were drop in replacements for the early oil burner Forester engines I think it is safe to assume that actuator is functionally equivalent to the unlabeled actuators on the Forester engines. This means the USB cable and 1K Ohm resistor test I ran on my Forester actuators at the electrical connector should be safe to use with the actuators on the one piece Legacy manifold even if the magnets on the butterfly mechanism have changed. The left and right actuators are identical, just mounted at different angles. Taken all together the mirror image rotation of the Forester left /right TGVs, mechanical examination of which end of the magnet is over the sensor in the actuator on each side when open/closed and the voltage measurement specified in 2011 Forester shop manual for TGV diagnostics implies that the magnet poles must be reversed left/right for the Hall effect sensors to work as expected. This has been experimentally confirmed for my Forester. Now I am going to study the 2016 Legacy manual for similar hints.

Edit2

OK, decidedly different. While the actuator sensor power to pins 2/3 is still 5Vdc the actuator motor power to pins 4/5 appears to have been reduced from 12Vdc to PWM 5Vdc. The sensor output voltages are different too. At idle the right position sensor are supposed to read 3.12Vdc while the left should read 0.82Vdc in the Subaru select Monitor instead of being the same which makes me wonder if the new white Legacy TGV magnets are more different than just physical size and strength and do not have the poles reversed left right. In which case swapping them would not work, but replacing them with the old black Forester TGV magnets might. Which is pretty much what the person who said the white magnets were incompatible with the Forester computer says they did as well as reusing the Forester actuators too. Hmmmm. Need to double check pictures of physical location of magnets vs sensors on the one piece manifold when the TGVs are open/closed.

Correction: I believe I was misreading a graph and the actuator motor powered is still 12Vdc. The lowered sensor output voltage could be due to different impedance in the circuit. The fact that the left/right sensor values are not the same at idle is probably the big clue.

Edit3

The odd angles make it a bit difficult to see, but the actuator motor and sensor are on a line more or less perpendicular to the mid point of a line through the actuator mounting holes in a "+" pattern. The mounting angles of the TGVs on the new Legacy one piece manifold are slightly different from the older Forester TGVs. The clocking angle of the slots to mount the magnets and gears to the flat spot on the shaft are different too. So probably not a trivial substitution. It occurs to me that if the white magnets are identical, one side or the other might make the Forester computer happy. Are the Legacy engine TGV codes only for one side?

Skenton said:

In reply

Are the Legacy engine TGV codes only for one side?

I haven't run it with them plugged in yet.  I will try that. I was afraid I might burn something out with the ecu wanting to turn them the wrong way. The way I connected them was to manually turn the flap fully open and put the stepper motor back on. And disconnect the wires. 

Can you remember anything about how the white magnet is constructed? In your picture below, there seems to be a lip at the near end but not the far end of the arc where the metal could slide into the plastic. But it is too thick vertically in the center unless there is a second piece of metal in the lower center. Which might make sense as a cost saving way to reduce the amount of magnetic material. Maybe put a small magnet in the center and "extend" it with a longer plain iron cover piece?

If the magnet can slide out using a screwdriver (with the help of some kroil), be flipped over and then reinsert it would be another way to flip magnetic poles if that turns out to be what is needed.

I would rather spend money on a lower milage engine than a second manifold, but it may come to that soon.

Skenton said:

I would rather spend money on a lower milage engine than a second manifold

Agreed. No need having an extra manifold at this point.. Looks like you are pretty committed to the swap. Might pull the trigger on the lower mileage engine so you can continue the fix investigation. LKQ on ebay does seem to have the best prices. 

Since jdf60 has confirmed that unplugging the TGVs does not cause any big problems I guess I should just commit and buy an engine. Codes are not an issue here while I tinker.

It is a bit more than I want to spend, but there is a 2016 Forester engine with 99K miles on Ebay for $485 plus shipping and tax that might let you sidestep the whole TGV issue since codes do matter for you. It looks like I have a few local-ish 2015-2016 options on car-part.com if I road trip a bit with the daughter & her truck.

2016 Forester engine ... let you sidestep the whole TGV issue...

2016 is the last year Forester with the old style 2-piece TGV/intake and PCV system. Other models changed over at different times.

In reply to mildensteve :

So do you know the details on the Oil consumption on the forester engines?  Did they fix that after 2013?  I thought I read that the newer style legacy wasn't as bad with oil consumption but not sure on the forester. 
 

anyeay, quick update on mine. Seems to be running good. Even with the misfire code. I really can't tell it is misfiring at all.  I've checked everything I know to check. Compression is great, coil pack and plugs are new, swapped  injectors.  Im curious to see if it's something related to the newer legacy engine that causes a false misfire code. Although all the sensors are from the forester. Code seems to always be there but it really isn't running rough at all. 
 

Once in a while it seems to start a little rough. I wonder if that is the intake runners.  

In reply to Skenton :

From this pic it sure doesn't look like the magnet comes out. But I can't remember much detail other than the pics. I do plan to take it apart again but we're needing to use it right now. Possibly in a week I'll have a chance to get it apart.  Was thinking I might replace the crank sensor to see if that might be the cause of the misfire code. I've read it can cause that. Anyway manifold needs to come off to get to that sensor anyway so we'll see. 

jdf60 said:

In reply to mildensteve :

So do you know the details on the Oil consumption on the forester engines?  Did they fix that after 2013?

Based on what I have read the 2013 and on are better.  I would stick to as new a model as possible.

I agree, they fixed the piston/oil rings issue pretty fast. Certainly everywhere by 2014 according to what I have read.

My Forester engine is loose and ready to pull once I disassemble and move the hoist and get it reassembled it at my daughter's house. Time to get serious about a donor engine.

Subaru recommends a whole bunch of different sealants, many of which have been superseded due to progress in the field.

As far as I can tell Permatex "The Right Stuff" should work for the timing cover, rocker covers and oil pan. What did you use?

The old Forester TGVs sensors output the same voltage for the left/right when the butterflys are open to the same angle. This is why the black magnets needed the poles reversed on the clockwise and counter-clockwise ends for the two sides.

My best guess is that the TGVs in the Legacy 2015+ one piece manifolds have identical white magnets for the two sides and the sensors output different voltages for the left/right when the butterflys are open to the same angle. Probing with a magnet and nail etc should easily confirm if this is the case or not. Then a fix can be designed.

In reply to Skenton :

Sounds like progress!  Yes I would recommend getting the engine ordered sooner than you need it, mine took a while. And when you do make sure you give them a note that you need a lift gate. Lkq on eBay says they provide a lift gate with their residential shipping, but that was need to my freight company. If I remember right on the lkq site the same engines were a little more $$  snd charged extra for a lift gate. 
 

also ask for a pic of the actual engine if possible. I wish I had. Mine was very corroded looking. Just cosmetic but still not preferable. Or maybe just order from a dry warm state! 
 

I did just use permetex. It worked great on both timing and oil pan. Just hand tighten the bolts snd let it dry 10-20 minutes  then fully torque.  I'm sure you know how to use it. 
 

also keep in mind the oil pan is different on the legacy it won't use the forester gasket. I had ordered one in anticipation of replacing it but just used permatex when I found it was different.  
 

couple other tidbits. Timing cover is difficult to remove.  But not aweful. Remove the legacy cover first for practice!   Also wiring harness would not fit back on forester  bracket, if I remember right the egr valve was farther away and it moved the harness forward a couple inches. I zip tied it down good. Had to cut the vehicle side harness retainer off the firewall to reach. Also the temp sensor needs longer wires as it is in a different location. I did use all the original forester sensors as none of the legacy connectors matched. Crank sensor bracket needs swapped also and is a little difficult to get out. Dont break it!  Don't forget the flex plate and sensor wheel along with camshaft sensor plates. They are easy and only go on one way. One thing I did different was to leave the long studs out of the engine to have more room, and screwed them in after. I think most people would leave them in to help line up the engine but I'd rather have the extra space for drop in.  I also sanded the dowels eith 400 grit and lubed them up, they were tight.  of course solo reinstall is tricky as usual with any engine. 
 

oh and the crank damper from the legacy seems to be working fine.   it is a one piece design with the oil pump adapter on the damper itself whereas the forester is a two piece design. 
 

final tip I can think of  I ordered two new idler pulleys but they were slightly too large and the belt wouldn't go on so I reused the old ones. Not sure what was up with that. Probably rock auto/ cheap parts issue.  Old ones are working fine  maybe the new will work on after the belt stretches a bit  and next time I'll order a slightly longer belt  

if I think of other tips I'll post them. 
 

Skenton said:

there is a 2016 Forester engine...

Well, I cheated.  At least it feels like it.  I got a 2016 Forester engine from LKQ on ebay.  Not the one you found but a lower mileage one (70k) from a warm state so it wasn't all corroded like jdf60's was.  And yes it was easy to adapt not having to deal with the TGV.  Still had to change out timing cover, valve covers, harness, flex plate, crank trigger, several sensors, bypass CVT cooling loop, engine mounts, harmonic balancer.  Intake, TGV, and PCV system are interchangeable except for one extra PCV "case equalizer hose" (not sure what it is for) on the old engine which is no longer on the new one.  Started up with no codes.  Driven for a day so far, time will tell.  I am going to keep up with this thread since I have emotionally invested in its success.

Words about LKQ:  No problems, engine arrived at my house on a huge pallet, shrink wrapped.  Only damage was a couple of wires cut on the original harness from the front end wreck the car was in.  Shipper was kind enough to back their truck down my driveway (I have about 100 feet) instead of leaving the  pallet at the street.  All in all, would do it again with them.

In reply to mildensteve :

Would you want to sell your old cam and crank sensors?   I just have a suspicion that one of those might be causing my misfire issue. I'm currently using the cam sensors from the legacy which I think are the same. I can't swap my old ones back on. I somehow managed to break the connectors off mine during disassembly. They were corroded snd weak.  If you want to keep the engine complete I understand.

sounds like your steps were mostly identical to mine other than my tgv from the new manifold isn't compatible. 
 

did you replace the idler pulleys and if so what part did you use?  Still curious why rock auto sent me a slightly larger pulley. 

jdf60 said:

In reply to mildensteve :

Would you want to sell your old cam and crank sensors?  did you replace the idler pulleys and if so what part did you use?

Are you speaking about the round thing at the end of the camshaft?  If so, I broke one of mine as well, connector being a very weak point.  Ended buying one from ebay  https://www.ebay.com/itm/393142724697  With free shipping (and a lowball offer of $19) it ended up being about $20.57  If you still want my old one that isn't broken PM me.

I have all new pulleys, water pump, idlers and belt ready to install.  I didn't want to waste new parts if the thing didn't work.  Easy enough to change them all.  I also got most of my parts from Rock Auto or eBay.  I had not checked to see if there were any differences.  Guess I should.

Edit:  Checked new Rockauto pulley = 3.23" diameter.  Used Subaru pulley = 3.15" diameter.  In my opinion, 0.08" diameter is not enough to make the belt too short.

In reply to mildensteve :

Yeah those round sensors at the end of the camshafts. I'll try to swap mine left to right first and see if that helps anything.  I may want to buy yours if your just getting rid of it.  I'll pm you sometime. 
my pulleys might have been slightly larger plus the belt being new. They old pulleys are not noisy so I guess I'll use them a while and try the new ones when I need them. 

 

I need to reinstall the AC compressor bracket since it has one of the lift points, but otherwise I am to the separate and pull the engine stage. I got the hoist moved over and reassembled and the floor jack is there too.

My starter had one bolt and one nut holding it on. The service manual claims there are two upper engine to transmission bolts on each side. Is that just wrong? I assume the long starter mounting bolt is one of the driver side upper engine to transmission bolts. Is the starter mounting stud threaded in to the engine or the transmission?

Worth asking before I start prying :-)

Edit

Never mind about the 2nd driver side upper engine to transmission bolt. I found it after I dealt with the AC bracket. Right next to the starter mounting stud but recessed some more.

Did either of you have any issue with the torque converter pulling out with the engine? The service manual talks about a special tool to hold it in place through the starter hole.

In reply to Skenton :

No problems.  Just make sure you remove all 4 converter bolts.  The hardest part of pulling the engine was getting the short, close tolerance guide pins on the engine sides to pop out of the transmission.  Even here in Texas they were slightly difficult due to corrosion.  You can see the pins and the 4 converter bolt holes in this picture.

Thanks. All 4 torque converter bolts are out (and not dropped down the hole). I sprayed the sides of the engine/transmission joint with Pblaster multiple times and have been letting it soak for a while.

I just bought a 2016 Legacy engine with 102K miles for $330 plus tax, 90 day warranty and no core charge. My daughter needs some stuff from Tulsa so we will go get it after the weekend. The donor car was really bashed in the the back but the picture from the front looked great :-) Knock on wood.

In reply to Skenton :

Nice!  So you got it from Tulsa?  I got a similar deal but from lkq on eBay, I never saw one close like Tulsa or I'd have gone that way to save freight. 
 

agreed, watch the converter. If I remember right Mine did slide forward some but you can push it back through the access hole or gap on top as you pull on the engine.

and my dowels stayed in the tranny. I just left them. I also remember that recessed bolt. The bolts seemed hard to get to in general. But I'm used to working on huge old Chevy cars! 
 

remove the radiator first, but you probably did already. I didn't because I wanted to replace it anyway, and I poked a hole in it. 

I guess I got lucky because I didn't even think to look at the torque converter as I was removing the engine.  I was busy trying to pry the engine from the transmission.  $330 for an engine seems like a great deal.  I paid significantly more, plus had to ship it from the east coast.

Subaru engines and transmissions get a death grip on each other.  I have never had a factory assembled drivetrain not come apart without starting with a thin chisel around various points on the top of the bellhousing.

I checked all the local places and looked on Ebay, but I found the best deal on car-part.com sorted by distance from my zip. In this instance the VIN code for the 2.5L FB25 engine really does not matter since we are swapping parts on the long block so I searched through the various offerings for 2015-2017 and ended up with the 2016 that I bought from Midway Auto up by the Tulsa airport.

Edit - Planning to pick it up tomorrow.

In reply to Skenton :

Nice!  How did the pickup go?  That's a year newer than mine. I believe the 16 and 17 models were more expensive when I was looking. Never even considered looking at carparts.com or anywhere other than lkq for a local engine. Good info for next time. And like you said we just need the long block. 

In reply to mildensteve :

But you did get a real forester engine right?That's worth more IMHO because you won't have to swap timing covers and all sensors, etc. 

jdf60 said:

In reply to mildensteve :

But you did get a real forester engine right?That's worth more IMHO because you won't have to swap timing covers and all sensors, etc. 

Yes a real Forester engine.  However, still had to change out timing cover, valve covers, harness, flex plate, crank trigger, several sensors, bypass CVT cooling loop, engine mounts, harmonic balancer.  Intake, TGV, PCV, and cam trigger wheels are the same on the 2016 as the 2012.