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2011 Forester Engine
propwash49
Member Posts: 38
in Subaru
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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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
Thanks, Bob.
The 3.0l H6 was called the EZ30, and IIRC the 3.6l is the EZ36. Can someone confirm that?
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.
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.
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.
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
PLEASE bring over the boxer diesel!
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.
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!
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:
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:
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.
Either way, I'd love to have that instead of crawling under the car every time with a diaper to absorb spilled oil.
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.
and with the extended oil change intervals I don't think it's worth changing the oil yourself any more.
Not to mention it's rewarding to accomplish something that's not even difficult.
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.
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.
requires oil changes at 7500 mi.
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.
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.
"The cylinder liners appear to be completely un-attached from the block walls (IE totally wet, no semi-closed anything)..."
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.
There was a block cutaway on one of the web sites; can't remember which. There were other descriptions that seemed to suggest one or two large block-to-head water connections at the end of the heads and that the heads were not identical on the two sides.
If that poster (in another forum) was indeed looking at an open cylinder block deck, it implies that Subaru has been able to make the cylinders rigid enough not to need semi-closed bracing at the top.
The semi-closed decks of the turbo and diesel engines must be sand cast, which is expensive. Each mold must be made of sand, then destroyed, and the sand cleaned out.
The open deck of the plain old engines was likely chosen for the new FB25 naturally aspirated engine, because it is cast with reusable clean steel die molds. This engine will soon be the basis for the turbo and diesel, too:
"...this new-generation boxer engine... will be positioned as a main engine and the starting point of (Fuji Heavy Industry's) future power unit strategy. Starting with the Forester, the new engine will be deployed in other Subaru products in the future."
http://www.fhi.co.jp/english/contents/pdf_en_60853.pdf
The head gasket must still seal across the top of the cylinder block. No matter what the design of the block -- even in the closed deck block -- the water passages around the cylinders must have openings across the deck to allow casting. The head gasket still seals those openings.
http://www.subaruforester.org/vbulletin/f88/2006-head-gaskets-problem-64464/inde- x2.html#post716946
But I think you are right in that separate cooling of the heads does allow a much better head gasket, which solves the historic leak problem.
Separate cooling of the FB25 head must mean that those water passage openings in the deck do not go into the head. In the illustration of the new head here, it is a cast pan with a solid flat bottom surface that goes against the top surface of the head gasket. The head gasket bridges over the water passage openings in the top of the deck, and is penetrated only by the tops of the cylinders. This would give the head gasket much more strength and contact area.
http://subarudrive.preprod.dcim.com/Win11/_images/cam.jpg
Back in 2004-2005ish they switched to a smaller filter due to the older larger filters being too close to the exhaust headers and caused overheating of the oil.
By moving it up to the top of the engine it's much futher from the very hot exhaust so this alone is a great advantage. The filters are also larger giving them greater filtering capacity.
I'm suprised they haven't moved to having a larger sump, this is very common on a lot of new cars these days.
-mike