softroader

Thank you, so much to learn here. So that raises a question: I'm picturing the center diff as having a similar function to say a rear diff, where one wheel can turn faster than the other in turns... similarly with a center diff, one axle might turn faster than the other (which the MPT will try to compensate for). Hopefully this is correct so far... So, with the MPT inactive (with the VDC system failed, or disabled), would the AWD system be able to tolerate having a (temporaily) mismatched tire without overheating like the viscous coupler in MT models?

How much could I expect to pay for a good used 4AT transmission with VDC? Without VDC? Or a 5MT? Why are the 2003 VDC or 2004 the ones you would want? What's the deal with the non-adjustable LH defrost vent? Which cars have that?

Interesting, hadn't though of that. So the 5MT isn't normally notchy like I experienced? I have only driven one so far. Too slippery gear oil causes synchro problems because they rely on having enough friction to spin up.

I'm lost here. What does this mean?

Thanks, good info. Good question too, got me thinking about it. It's not a mental ego thing, I could train a monkey to drive a stick, I think it's a combination of many years of driving a 5-speed so it's become second nature, and my first impression of early automatic transmissions when they were inefficient, loud, slow and annoying, and failed a lot. First impressions... time to take another look. I drove a 2001 H4 OBW with the 4AT on city streets this week, and liked the convenience of the AT and the way it shifted. Not like the early ATs at all. Even with the H4 it didn't seem underpowered. The 2007 H4 5MT OBW I drove last week was noticeably more responsive, but that's also a different engine so whatever. I didn't like the feel of its 5MT, it seemed notchy and hard to shift, but part of that is getting used to the feel and I think the clutch wasn't fully disengaging and needed freeplay adjustment or something. In any case I expect the H6 with the 4AT would be a great combination, and I'm driving one (a high mileage 2001 H6-3.0 LL Bean) tomorrow so I'll find out for myself. Gas mileage, if it really is 2-3mpg, isn't a big issue. Cars around here don't rust at all and it's easy to spot one that has been in a rust area too long. I'm leaning strongly toward the 2001-2004 H6 4AT based on all the helpful comments here about reliability and availability of the 4AT and 5MT, and the AT really would be so much better offroad.

Sorry if this is a dumb question. Does the 10mm refer to the thickness of the drive gear inside the oil pump? Is the thickness of the housing the same in all of these? If not, do other parts needs to be changed? I have been running the same (similar to the EJ25) oil pump on my 22RE for 409,000 miles with good pressure, they don't seem to wear much at all. Wondering why Subaru didn't just start out with a 10mm pump and stick with it...

Can the 10mm or 11mm oil pump be installed on all of these? Sounds like a good way to compensate for the reduced rod bearing oil flow that GD describes. Cheap insurance for $110.

Thanks Bennie. Makes me a lot more comfortable with the EJ251.

Good info. Do you worry about the added complexity of the VDT system with all those extra sensors? I'm looking for reliability, especially when off-road. Is this something to worry about? It sounds useful but is it prohibitively expensive and difficult to repair when it fails? Off topic rant: I look at all the complex features on the new 2020 vehicles (not just Subaru) and shake my head, so many are just crutches for incompetent/complacent drivers, and cost a fortune to fix. Lane keeping assist? Seriously? If you can't do that yourself you shouldn't be behind the wheel. Maybe put your phone down and pay attention to the road while you're driving... old school, I know, but it works.

Thanks Bennie. I think the poster who described his MT puking 2nd gear teeth wasn't driving it that way, and it does sound like an exception and not typical. Maybe it was abused before and had stress cracks or something. And Numbchux just described tha ready availability of good used 5MTs, so I'm not worried. I have two spare 5MTs for my 37 year old Toyota DD, same idea. So the EJ251 inherited the bad reputation of the EJ25D? That is reassuring. Head gasket replacement doesn't look too difficult. JDM EZ30 H6 engines are readily available, they run about $1100 around here, maybe $1200 delivered. If I end up with a 2000-2004 H6 4AT Outback, I will probably just buy a JDM engine while they are available, compression check and borescope it, and store it for possible future use. Maybe try to find a good used 4AT also. Then if one fails, I have one. I intend to keep my Outback for a long time and don't want to worry about the supply of major components drying up (been there, done that).

Numbchux, I can't thank you enough. This is exactly the kind of big picture insight I was hoping for, very, very helpful to me. I just got back from driving a craigslist 2001 EJ251 4AT with 270,000 miles, it needed work but it drove well and it was dirt cheap, didn't buy it because with an AT I want an H6. Gave me a new appreciation for these older Gen 2 OBs (and I'm not biased, my Toyota DD is 37 years old with 409,000 miles). I have been overthinking this, but that's easy to do with an unfamiliar vehicle, I have a Black Belt in my DD but Subies are new to me. For many years I have wanted a silky smooth 6-cyl car, in part because my DD sometimes vibrates so much I need a kidney belt and I have had enough vibration to last me several lifetimes... always thought that would be a V6 until I heard about the Subaru boxer engines... my intended use is light offroading (forest roads, occasional bumpier stuff) while exploring and dispersed camping off pavement... Sierra Nevada, Colorado Rockies, maybe up into Canada... lots of freeway miles where noise and comfort makes all the difference over many hours. So the H6 appeals strongly. Though when my friend gave me a ride one time in her H4 I couldn't believe it wasn't a V6 it was so smooth. I'm an MT guy but I'm thinking it wouldn't hurt to consider a 4AT for the softroading part, especially considering that when I go on an exploring roadtrip in the current MT DD I shift into 5th and stay there for hours on the freeway anyway. The posts about a failed AT meaning the end of the car kinda ruined that, but you have turned that around with your post about the availability of good used ATs. And I agree about the 2005+ CANbus cars. As a network engineer, this is like depending on an eggshell to keep the car running. Too many essential functions depending on a single point of failure.

This is exactly why I'm having trouble deciding which 2000-2004 Outback to get. One moment I'm leaning toward the H6 with AT because of the extra torque and advantages of the AT off-road, then I come across a post (here, I think) that says that usually when the Outback AT fails it's so expensive to replace that people usually just give up on the car. So back to the EJ25 with 5MT, simpler and more robust than the AT, no worries about the AT failing, just timing belts (I've come to terms with that, easy to replace and no big deal), and head gasket problems (I can do that myself, and lost of good info around). So, leaning toward the 5MT. Then I read your post... the MT decided to puke up all its 2nd gear teeth on an unmodified vehicle? AYFKM? Why is it so hard for Subaru to properly engineer their vehicles? So now I'm just bouncing back and forth between the H4 and H6, trying to decide which money pit of problems would be better.

Thank you. Any opinions on the 7mm oil pump issue? Do these 01-04 EJ25 engines have it?

Having not seen either one for 01-04 (I have only seen a 2007 EJ25 engine up close), what would I look for?

Thank you. When looking at a used Outback, other than the data plate under the hood which the engine might no longer match, is there an easy way to determine what engine is in there before buying it? Do the DOHC EJ45 engines look different from the SOHC versions?

Do the 00-04 Outbacks use the EJ251 engine? Wikipedia says "The EJ251 was soon replaced by the EJ253 in many models due to its improved cooling to aid in head gasket life and improved engine management and sensors. The EJ251 commonly experienced head gasket failures resulting in interior channel breaches or exterior fluid leaks due to the continued use of a single layer coated gasket first introduced on the EJ25D." I'm looking for an 01-04 Outback (my first Subaru, and I'm just beginning to learn about them) but this worries me. Does replacing the EJ251 head gaskets with the MLS gaskets fix this problem? If it does I'll just do that when it comes up. Also concerned about the 7mm oil pumps that GD routinely replaces with a 10mm, does the EJ251 have this, and is the replacement easy to do? I want nothing to do with the 2005+ CANBUS Outbacks, too fragile.

Of course it's a matter of individual preference, but would you say it's worth giving up MT fun for the advantages of an AT off-road? I'm really torn on this, I have been driving a 5-speed MT for years and years and love it (and will keep it when I get the Subie), but there's no doubt that an AT is better off-road especially at slow speeds and around obstacles, a MT clutch won't live too long under those conditions. Before you bought your 03H6OBW did you drive a 4-cyl MT OB? Impressions? Are you still glad you got the H6 AT? I'm leaning toward the H6, I like the timing chain, fewer head gasket failures, more power and torque, etc. Just wish they had offered a MT with it in Gen 2 OBs (retrofitting one is more headache than I'm willing to take on, especially with California smog testing).

New to Subaru and these forums. I'm looking for a Gen 2 or Gen 3 OB to be used for softroading and camping but having trouble figuring out which combination of OB, engine and transmission will best suit my needs, and which engines to avoid. I've been wrenching on cars for a long time so I don't mind doing things like replacing the TB, head gaskets, or buying a rebuilt Subaru short block and putting heads on it etc. After hours reading and searching these and other Subaru forums I'm getting a bit lost in all the information, largely because I'm not clear on exactly which engines were used in which model years even after looking at cars101.com and the Subaru engine wikipedia pages. Many of the posts here have been very helpful, especially those by GeneralDisorder and the other gurus, but I still have questions that I'm hoping the experts here will respond to: I have a strong preference for the MT, which unfortunately pretty much rules out the EZ30 engines for me. I like the EZ30 engines because I prefer timing chains and they don't seem to have the same head gasket problems as the EJ25. Not sure I could live with an AT to get the EZ30 but maybe. GeneralDisorder posted somewhere here (sorry, I'm not sure how to quote a post from another thread) about the 2005+ OBs being in "CANBUS h*ll", a view I strongly agree with. Too many fragile and nonessential things on the CANBUS that can fail and kill it, disabling the vehicle. Not a good thing miles from paved roads. So I think that rules out the Gen 3 2005-2009 OBs for me. Good news there is I won't have to deal with expensive immobilizers either. GeneralDisorder posted about EJ25 family engines that have 7-9mm oil pumps and are even more prone to rod bearing failure caused by increasing main bearing clearances due to soft case aluminum alloy. Exactly which engines are these, and what year OBs were they installed in? Are these the EJ251 engines in the 2000-2004 OBs? The ones with a worse head gasket problem than the 2005-2009 OB engines? If my understanding is correct (not likely at this point) it looks like my choices might boil down to these: A 2001-2004 OB with the EZ30 6-cyl engine and 4AT. Good: timing chain, head gaskets, JDM EZ30s are cheap and available, more torque, AT better at slow speeds off pavement than a MT, can mod a 4WD switch. Bad: I want a MT, an AT has much more to break than the MT. A 2001-2004 OB with EJ25(?) 4-cyl engine and 5MT. Good: 5MT. Bad: timing belt (not so bad), head gaskets, rod bearing failures (is this the engine with the feeble oil pump?) Confused about exactly which EJ25 version was used in this OB. A 2005-2009 OB with EJ253(?) and 5MT. Good: better engine 2006+ (175hp, variable valves). Bad: CANBUS h*ll, expensive immobilizers. I know that's a lot of muddled and probably not quite right information. Can someone please help me sort it out? Thanks in advance.