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Transplanting an H6. . .

20281 Views 48 Replies 19 Participants Last post by  David Zablotny
So one of the subies I bought recently and regretted almost instantly was a 2000 OBW, nothing special, just a base model in white with the gray interior. It was advertised on CL as having blown headgaskets and was priced right ($1200) but had no pics and no mileage.

Cars like that don't stay on CL for long so fortunately I was the first to call and asked a few questions, the answers satisfied me to the point where I made a verbal commitment to buy the car, provided it was what he said it was. One of the questions I asked was what the mileage was. . .he wasn't sure but said it was definitely under 200k. Interior was "very clean" and the body was dent free.

Showed up cash in hand with the trailer hooked up to look at the car, and was hugely disappointed to learn once we hooked up the boost box that it had not just a little over 200k but a whopping 276,000 on the clock. VIN also indicated it was a 2000, not a 2001. That alone was enough to turn me off but the body was solid and interior clearly had potential, so rather than back up and run off I negotiated and wound up taking it and a very nice set of Michelin Hydroedge tires in 225/60-16 the guy had squirreled away for the car.

I'll say I let the fever of the deal get me because of the three Outbacks I bought that week with bad headgaskets (that's unusual for me. . It's usually like one a month but I had folks lined up waiting for cars), this was by far the worst deal. I built the other two and gave each a 2 week shakedown session before I even touched this car. It sat in the yard collecting leaves as I couldn't figure out how I'd be able to do a proper engine rebuild on a car with this many miles and still have any margin left over to make it worth my time.

I considered parting it, but nobody would want to buy driveline pieces with just shy of 300k on them, and body parts (aside from the front end) never sell well. . So it just sat.

On a whim I had my local dealer run the VIN for their own service records and was pleased to learn it had been a one-owner car for at least 260 of those 276k miles. . . Bought locally brand new in 2000 and driven by a college prof with a 120 mile daily commute (round trip), a longtime Subaru enthusiast. The guy I bought it from bought it from them literally as it was headed across the scales to the crusher! He'd been dismayed with the availability of good 2.5's so he just mothballed it unitl it went on CL.

Then I bought a rolled 2002 LL Bean. . .mostly for the interior. Got it at the sale cheap as the mileage was unknown, and I had the interior sold out of it pretty much before I brought the car home. Once I got the twisted metal free enough to start it I was pleased to discover it had a reasonable 169k on her odometer, and the entire engine and driveline was dry and clean and showed evidence of a good bit of recent service, including spark plugs and vc gaskets. Engine was quiet and smooth, not even a squeaky tensioner bearing.

I parted out a VDC 6 cyl once before and breifly considered swapping the driveline over to another 2nd gen outback but once I pulled the motor and saw all the differences changed my mind.

Changed my mind again now that I had a good 6 cyl driveline and a good 4cyl body. The little white outback was about to rise from the ashes and come back better, faster, stronger :)

This time I decided to try and approach it like the factory would. . . Drop out the whole engine and trans as an assembly on the crossmember with steering rack and suspension still attached. Do that on both cars, just move the powerplant unit straight across. Less bolts to undo, no messing with torque converter bolts (always my fave thing to do), and I get to swap over half of the suspension and 90% of the rotating assemblies on the hi-miles car (what we dubbed the white base outback). Once all the bolts have been turned the only moving parts on the car with 276k on them will be the rear axles and bearings.

Still, it's turned out to be a monumental undertaking. Even though the entire process is a bolt on, plug in swap, it's been about 4 8 hour days so far (one full day to strip the parts car down to a naked hull), and I've still got about 10 hours to go. A short list of what has to be swapped:

Rear diff
Cooling fans (H6 fans are thinner, 4cyl will not work)
Dash wiring harness
Cluster (I think. . .I'm not taking chances)
Front body/engine wire harness
Cross-dash harness including connection to underhood fuse box
Trans cooler lines and inline filter (H4's have the filter on the trans. Converter lives in this spot on H6 so filter was relocated to the driver's fender--I forgot about this and sent the parts car to the crusher with those $200 pieces still attached)

That's just to get it running. If you want some of the other amenities to work (might as well. . . It's more work to leave them off), you need to swap these goodies:

-Entire underdash HVAC system (6cyl cars all have auto HVAC)
-Combination switch (so you can have adjustable delay wipers)
-Lighted bezel around ignition lock (might as well, ey? Wires are there)
-Door harnesses (assuming you want heated mirrors)
-Windshield (assuming you want wiper de-icer)
-Rear body harness (or pare out the heated seat harness)

I drew the line at the autodimming compass/mirror. Don't see much need for it as I generally know which way I'm headed by the sun or GPS. I also left out the heated seats as I'll be putting an aftermarket set in. I don't want leather in this car as I'll probably wind up driving it myself and I'm not a huge fan.

As of right now it's in the car and running, although the exhaust and rear diff haven't been swapped. It's also still using the 4cyl fuel pump which I plan to leave in for a little while to see if it'll run properly on it. Might be news you H6 guys with failed fuel pumps could find useful.

Some comments on Subaru's construction methods:

I've always loved working on Subies. . .this one being no exception. Stuff is assembled with service in mind; it's very rare that you have to pull major components to gain access to minor ones. The hardest part of reinstalling the engine/trans/crossmember assembly? Lining up the steering rack u-joint with the steering column. Everything else was a cakewalk. . . Including sliding at least 800lbs worth of driveline under the car and raising it into position. God bless you Subaru for putting studs on the body to align the crossmember!

Wiring: I cannot fathom some of the decisions Subaru makes when it comes to building wire harnesses. They must have dozens of part no's for the cross-dash harness (for example), each with a slightly different wiring config for different options. . . But all include heated mirror wiring if the car has power mirrors. Know what doesn't have the 2 extra wires for heated mirrors? The door cords. 2 extra feet of wire per door but it's not in there. HVAC wiring is incorporated into 3 different harnesses, including the engine. The Auto HVAC systems use entirely different wiring, so going from a base to limited with the same engine and trans means a different wiring harnes part no. Things like heated windshield that could easily be packaged outside the main harness are incorporated into not one but TWO different harnesses. On the first gen cars it's even in with the engine harness!

And test connectors. . .these things are EVERYWHERE! And they look just like a regular connector! Make them all red or print TEST on them or put a tape band around them or SOMETHING! One of the more maddening elements of reassembly has been making sure any unconnected connectors are truly test connectors and not something I forgot and buried its mate under the carpet or something. Nothing like getting the dash fully reassembled only to learn that connector behind the HVAC wasn't a test connector, it went to the mode control motor (I didn't do that, but it would have been very easy to).

Anyway, pics to follow. It's raining so I'm stuck inside for the moment, otherwise I'd be out swapping the diff and exhaust. . .and wondering if Grizzard is gonna get back to me on those trans lines I need or if I'm stuck ordering them from Subaru :p
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are the springs different between H4 and H6? just wondering if the engine is heavier I guess.

man, what a project.

I'm gonna give you one of these;

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Well that's quite a project you took on! Shame you missed the filter re-location parts. One of the first things I have learned about these Subaru's is that the wiring guru's were insane.... I bet the harness, before installation, had color coded plugs at each of the ends for the assembly workers. Match the colored plugs and connect together.

and you are doing this with rain in the forecast....

Be looking forward to the pics!

Awesome, man! Thumbs up!
I'll keep following this thread ;)
I've no idea on the springs. I've heard they were a bit but that might be wishful thinking on the part of folks grabbing up the parts. I went ahead and swapped the struts/springs from the H6 as they have 100k less miles on them and aren't leaking. Whether they dampen the ride still remains to be seen but it's not like changing struts at this point would be a major undertaking.

I'd love to thread pics into this article but my laptop's bit the dust and I've been typing this on my tablet. . . Thinking I'll just post some links to the picasa albums. You're a smart lot, you can figure out what's what :)

Thanks 1LT. . What's that gif/meme from btw?
Thanks 1LT. . What's that gif/meme from btw?
I pulled it out of the Rubberbandits video for Horse Outside. one of a handful of songs that mention Subaru.

(many 'f' bombs in the song so - you've been warned)
The front springs on a 2002 H6 will be heavier/stiffer than on a Gen2 H4. This is evidenced by the fact that they give a pretty significant lift when people swap them into H4 cars. Also, 2002-2004 H6 cars have 7.9" of clearance stock and H4s have 7.3".

The H6 engine weighs almost 400 lbs. I think the H4 is somewhere between 250 and 300, but I can't remember for sure.

Looks like quite the project!
some pics
Yikes! Well, it does make it easier to change the plugs!:29:

Yikes! Well, it does make it easier to change the plugs!:29:
So the heater core, too :))))

Great pics, though! Keep it up! :29:
Very impressive. I agree with the mechanical engineering aspect. This is one of the easier cars I have ever wrenched on.
Great Job :29:
Very impressive. I agree with the mechanical engineering aspect. This is one of the easier cars I have ever wrenched on.
Great Job :29:
Mechanical is easy. Finding the wiring diagram that actually matches the car is the hard part.
Yikes! Well, it does make it easier to change the plugs!:29:

I threw those pics in as I was gonna add them to one of the how-to threads about changing plugs on the H6 saying "dunno what you're all on about. . . I had no problem changing my plugs :D"
I threw those pics in as I was gonna add them to one of the how-to threads about changing plugs on the H6 saying "dunno what you're all on about. . . I had no problem changing my plugs :D"
Glenn already beat you to that! :p
Lol totally forgot about that. Man talk about a nofun job. . . pulling the front end of an H6 down twice!

Made some progress yesterday amid the rain. . .

-exhaust swapped. Not only is the midpipe/muffler combo shorter it's also larger on the H6 vs. 4cyl. H6 has a little bypass widget in the muffler that's supposed to change the tone at a certain exhaust pressure.
-Rear diff and driveshaft swapped. Driveshaft is the same length, I swapped it as the original 276k unit had a boot on the DOJ starting to fail. It's not serviceable according to Subaru.
-Swapped the "puddle lights" over to the door panels. Wiring was already there, might as well add 'em.
-Swapped on the heated mirrors. Fogged them semigloss black. . . not repainting anything white on this car (doesn't need it. . . bumpers do tho).
-Reinstalled headlights after restoring them. GF has figured out how to do this and loves to help out by taking on that task (and detailing the interior)
-Reinstalled steering column after a 2 hour battle getting the u-joint reconnected. Finally figured out it was easier to unhook it from the rack, hook up to the column first, then the rack.

Waiting on parts now. Trans cooler lines are hooked up temporarily but I don't want to test drive it without a filter so I'll wait on the new hard lines from Subaru. Also need a radiator fan shroud, mine didn't survive the crash.

In the meantime both bumpers are off to the body shop, carpet is hung out to dry (in the garage. . . usually let it dry in the sun but the weather's not cooperating this week) and i'll busy myself upgrading the stereo and tinting the windows (winders for my fellow southerners).

I have one connector underhood I can't identify that's not connected. . grey 4 pin square near the brake booster. The 2001 LLBean I bought from New York shows up today, i'll probably just figure it out when it gets here.
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-Reinstalled steering column after a 2 hour battle getting the u-joint reconnected. Finally figured out it was easier to unhook it from the rack, hook up to the column first, then the rack.

^^^ That info is now tucked away, Thanks!

I have one connector underhood I can't identify that's not connected. . grey 4 pin square near the brake booster.
Don't know what it controls but here is a pic of mine.



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That's it. No idea what it does either but ill go digging
So are the H4 and H6 driveshafts identical?

That would be a welcome bit of news.
I edited the pics (deleted some dupes) and added captions. Lemme know if it makes more sense now.
CNY Dave said:
So are the H4 and H6 driveshafts identical?
They are. I had the 4cyl. driveshaft and rear diff in as I raised the engine/trans up to marry to the body. . . I considered leaving the 4cyl driveshaft in but after I noticed the torn boot I swapped it. I left it connected to the rear diff as I swapped it as I'm lazy :)

But yes, they're exactly the same length and flanges at the rear diff are the same. . . so they're not specific in any overt way.

Relay above the brake booster is apparently part of the AC system. . . or so sayeth Subaru. Thanks much for the pic OldStyle. . . fwd'd that to my dealer for ID and pricing ($70 my cost---ouch!), then found one I had squirreled away with the other H6 motor/harness I have in the barn.

Would have had a **** of a time doing this without having a parts car or two laying around. I'm not much for documenting stuff as it comes apart and instead tend to trust my own knack for figuring out where stuff goes but I'm also prone to lose bolts/clips/etc. . . I never throw those away when parting a car out so I have a huge collection of them now, they're just not sorted. It's also nice to be able to just stick my head under the hood/dash of another car and go "oh so THAT's where that goes!" :)

I'd also like to say that I work without a lift and don't really have any special tools. I did every bit of this in my driveway (which is level and concrete fortunately) with a roll around floor jack, transmission jack, engine crane (AKA cherry picker), and a few jack stands. No help lining the engine up or dropping it out, just cautious use of the hydraulics. I do have air tools and a decent-sized compressor but they're not absolutely necessary. I used air impact on the larger bolts/nuts, everything else I did with a little electric impact which works great for most bolts/nuts up to 14mm head size.

Not bragging just mentioning it to point out that this is a swap that pretty much anyone is capable of doing. . . if you have the time and the short list of tools I mentioned. I'll have about 40 hours in this one by the time it's all over, 2nd one will probably take half the time (oh yes. . there will be a 2nd!).

Didn't do anything on it last night for a couple of reasons: waiting on trans filter kit (only $90, not $200 like I originally thought), fan shrouds, and bumpers to come back from the body shop aaaaand. . .


I'll get back on it Friday night/this weekend. It's running but hasn't been on a test drive yet as I haven't filled the radiator all the way up (top hoses get in the way of R&R'ing the fans).

At some point I will do a better write-up with pics inline, maybe make a .pdf. It's really not difficult, just time-consuming. Just repeat the mantra "how do you eat an elephant? One bite at a time!" when you get overwhelmed. :)
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