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2011 Forester Engine

I understand that the engine in the 2011 Forester has gone from a single belt-driven OHC to double chain-driven OHC. Does anyone know if this is a completely new engine, or is it a derivative of an engine that has been around for awhile?
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Comments

  • rshollandrsholland Posts: 19,663
    It's completely new, and goes by the following IDs: FB20 (2.0L) and FB25 (2.5L).

    The old EJ engines, especially the EJ25 were wildly oversquare with a much bigger bore and a very short stroke. The new FB 20 is undersquare, and the FB25 is just slightly oversquare.

    Bob
  • ateixeiraateixeira Posts: 72,587
    So now we have our new nomenclature.

    Thanks, Bob.

    The 3.0l H6 was called the EZ30, and IIRC the 3.6l is the EZ36. Can someone confirm that?
  • aathertonaatherton Posts: 617
    edited October 2010
    The new naturally-apirated (non-turbo) engine has these changes:
    1. SOHC changed to DOHC.
    2. Cam drive changed from 1 exposed rubber belt to 2 enclosed chains.
    3. Top deck of cylinder block probably changed from open casting to the semi-closed casting of the present XT DOHC engine, which continues unchanged. The open deck was the cause of head gasket leaks.
    4. Oil filter changed from under engine amid exhaust headers, to top front of engine.
    5. Single coil changed to coil module on each plug (direct ignition).
    6. Synthetic oil required.
  • ateixeiraateixeira Posts: 72,587
    A lengthy list of improvements, but it makes you wonder why they didn't add Direct Injection and bump HP up to 180-200 or so.
  • prigglypriggly Posts: 642
    Subaru may finally have produced an engine that is no longer prone to the dreaded head gasket problem because this new one is of semi-closed deck block design.

    Hurrah! They may have been geologically slow in bringing this engine to market but at least they got there. Time will tell if it is in fact reliable. The old one was not.
  • saedavesaedave Chicago, ILPosts: 683
    Subaru may finally have produced an engine that is no longer prone to the dreaded head gasket problem because this new one is of semi-closed deck block design.

    I hope you are correct, but where is the semi-closed deck block specified?

    The problem MIGHT be solveable by the smaller bore also. I don't know whether the failures started with the change from 2.2 to 2.5 liters.
  • aathertonaatherton Posts: 617
    edited November 2010
    ... where is the semi-closed deck block specified?

    That is the assumption, and the question. The old and present DOHC turbo engine has the semi-enclosed cylinder block deck, so it is assumed that the new DOHC naturally aspirated (NA) engine has the same.

    Why else would Subaru roll out a new NA engine with DOHC and supposedly lifetime chain cam drives, only to have the complex chain drives at the mercy of head gasket leaks caused by the old engines's open decks?

    Subaru has posted that the semi-closed deck of the DOHC XT and diesel engines was to stop head gasket leaks, so it is assumed that the new DOHC NA engine was designed with the same semi-closed deck as the DOHC XT and Diesel:

    "... The BOXER DIESEL adopts a semi-closed cylinder block deck to improve the rigidity around the head gaskets, following the precedent of the semi-closed type used in the Subaru EJ20 turbocharged gasoline engine."
    http://www.boxerdiesel.com/engineering/en/03.html
  • morin2morin2 Posts: 399
    Please, please, please, Subaru bring us the boxer diesel next. What good will the new DOHC gas engine be when gas is degraded so much by more ethanol.

    PLEASE bring over the boxer diesel!
  • aathertonaatherton Posts: 617
    edited November 2010
    I think that with the new chain-driven DOHC, Subaru has brought us their last pure fuel engine, which they did in preparation for its next evolution to hybrid.
  • nine51nine51 Posts: 78
    4. Oil filter changed from under engine amid exhaust headers, to top front of engine.

    Please tell me they haven't put the filter on top of the engine looking down. Where does all that oil in the filter go when you remove it? All over the place. My 944 Turbo has an inverted filter at the front of the engine and I have to pack a half-roll of paper towels around it so it doesn't puke oil all over the engine when I change the filter. The previous Sube oil filter location was just great. I could pull the oil drain plug and remove the filter without moving the oil drain pan. Took me 15 minutes to change oil and filter.
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,459
    They have actually included a cup that catches the oil that drains out as you remove it. I had the same concern as you when I first saw that.

    In recent years, the exhaust pipes wrapped around the filter location, making removal more difficult than in the past when the filter was easily accessible to remove and install by hand. That said, I agree that the oil change is a simple job on these cars... just not if you try to do it by hand!
  • nine51nine51 Posts: 78
    Opps...looks like the ads that run here in the Edmonds forums may have just answered my question. After my last post, an ad for Subaru popped up on the right side of the page and it shows the front of the engine, with a sideways mounted oil filter near the bottom of the block on the passenger side. That's OK, still accessible and won't drain the oil all over the engine.

    I know some web sites track where you are going on the site, but this is creepy!
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,459
    I know some web sites track where you are going on the site, but this is creepy!

    Hahaha! I know what you mean. I visited a plumbing supply store online last week and now I seem to be getting a lot of advertisements for plumbing supplies. :surprise:
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,459
    edited November 2010
    it shows the front of the engine, with a sideways mounted oil filter near the bottom of the block on the passenger side.

    I think that one is the 3.6L H6.

    This is a photo of the new 2.5L from the cars101 site - note the oil filter just to the left of the oil filler cap:

    image
  • aathertonaatherton Posts: 617
    edited November 2010
    "... The previous Sube oil filter location was just great. I could pull the oil drain plug and remove the filter without moving the oil drain pan.

    I have changed my Sube oil and filter many times, cursing at the gusher of oil to the right side and the inaccessible filter on the left side, never realizing that my huge radiator drain pan might catch both. Still not sure I want to risk it.

    But I still look forward to the new Sube filter on top of the engine.
  • ateixeiraateixeira Posts: 72,587
    Also, I wonder if the OEM filter itself has one of those anti-drain back valves that prevents oil from flowing backwards?

    Either way, I'd love to have that instead of crawling under the car every time with a diaper to absorb spilled oil.
  • nine51nine51 Posts: 78
    AHHhhh nuts. Looks like that is going to be a mess to remove.
  • If this refers to the top-mounted filter of the 2011 engine, how is it going to be a mess to remove? Have you actually looked at one?
    It would appear to be a lot easier and cleaner to remove than the one buried up in the header heat shields under the engine.
  • What is the big deal you still have to get under the vehicle to change the oil,
    and with the extended oil change intervals I don't think it's worth changing the oil yourself any more.
  • ateixeiraateixeira Posts: 72,587
    For me, I've seen dealers overtighten filters (badly overtighten), so I prefer to do it myself.

    Not to mention it's rewarding to accomplish something that's not even difficult.
  • I agree they sometimes also overtighten the plug and you have to listen to a sale pitch for unnecessary service.
    But If they screw it up it's their problem.

    I have been changing my own oil since 1957 up to about four yrs. ago when I decided that it's time to put away that oil pan.
  • aathertonaatherton Posts: 617
    edited December 2010
    "What is the big deal you still have to get under the vehicle to change the oil,
    and with the extended oil change intervals I don't think it's worth changing the oil yourself any more."


    Draining the oil is a lot easier than removing the old filter. On the 2009-on models without the plastic under tray, the oil plug can be reached and the oil drained without raising the car. But accessing the filter up in the headers requires raising the car, and getting yourself right under the filter which is buried up in the header shields. The filter is a mess to remove, and the header shields must then be cleaned of oil, as well as the ground and your hands. The top mounted filter on the 2011 is a big improvement in ease and cleanliness.

    Extended drain intervals do not apply to Subaru, whose intervals stand at 3750 miles for the X under all but long Interstate commutes or trips, and 3750 miles for the XT under all conditions.
  • ateixeiraateixeira Posts: 72,587
    Isn't it 7500 miles with synthetics for 2011+ models?
  • I'm referring to the 2011 model, the owners manual maintenance schedule
    requires oil changes at 7500 mi.
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,459
    edited December 2010
    The filter is a mess to remove, and the header shields must then be cleaned of oil, as well as the ground and your hands.

    I agree, Allan, though I doubt I feel as strongly about it. In addition to this, the exhaust piping is likely simplified as it does not need to route around the filter location underneath the car.

    The older generations (pre-2005, I think, for Outback - not sure about Forester) routed the exhaust differently (behind the engine rather than in front of it), so there was more room for the filter (and it had a larger casing as a result), but the exhaust also extended further toward the ground, which resulted in less ground clearance and a greater likelihood of damage to the pipes if the car bottomed out.

    So, in the 2005+, we ended up with better clearance, but more difficult/messy oil changes.
  • aathertonaatherton Posts: 617
    edited December 2010
    "Isn't it 7500 miles with synthetics for 2011+ models?"

    For the 2011+ models, synthetic is required.

    For the X it is 7500 miles except 3750 miles for severe duty, which consists of stop and go cold weather driving that most people are doing now.

    For the XT it is 3750 miles, as the turbo engines are considered to always operate under severe duty.
  • aathertonaatherton Posts: 617
    Concerning item 3, I just read in another forum that:
    "The cylinder liners appear to be completely un-attached from the block walls (IE totally wet, no semi-closed anything)..."
  • danielldaniell Posts: 128
    Aatherton, what is the implication of that design for the headgasket reliability issue?
  • saedavesaedave Chicago, ILPosts: 683
    There is another quote that may provide the answer:"Cooling has been optimized by using separate engine cooling circuitry for the block and the head, resulting in improvements in fuel efficiency and output characteristics."

    Separate cooling circuitry could suggest that there are no water passages sealed by the head gasket which certainly could solve the problem. Similarly, cooling circuit separation distinguishes the 3.6l from the 3.0l engines.
  • ateixeiraateixeira Posts: 72,587
    That's interesting. Any images of the new heads/gaskets?
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