Can anyone explain the difference between the Phase1 and Phase2 2.5 liter engines?

DOHC and SOHC respectively, I think. Hopefully someone more knowledgeable can help you out. I did do some research on it for a friend at one point, and the origional (Phase 1) engine I think required premium fuel and only made 155 hp.

96 phase I's were 155hp and required premium fuel. 96+ phase I's were changed to solid lifters, upping the hp to 165. the octane requirement was also lowered to 87.

There is more to it. I think you'd find the full story on NASIOC or the old i-club if you really want to dig into it.

 

Phase I

DOHC

Central thrust bearing on crank

Has an EGR

4 bolts holding tranny bell housing

 

Phase II

SOHC

Crank thrust bearing moved to one end (rear?) Lessening / eliminating a crank walk issue (I've rarely heard of this happening)

My dealer told me that the casting in the bottom end was beefed up. Heavier ribs, etc in the crank area.

No EGR circuit

7 (?) bolts holding tranny to engine. The extra ones are additional, so older trannies will bolt up to newer engines and vice versa.

I've heard that they played with piston pin offset and bearing area etc as part of trying to get rid of the piston slap. I can't substantiate it though. For the most part, I think they just paid closer attention to tolerances to fight this problem.

Rev limit is a hint lower on the Phase II (by 250 rpm I believe).

 

The hp stayed the same at 165. The torque rose from 162 to 166. (I'm leaving out the 1995 engine here.) I think the revs for these figures stayed pretty much the same. More importantly, the curves were "fattened" in the midrange. Something like 15 or 20% better for the Phase II. Also, gas mileage improved (5 or 10% maybe?). The biggest contributor to these two was the SOHC design. Considerably less losses.

 

That's about all I can think of right now.

 

Commuter

This may be trivial to some, but since I owned a 97 OB before my 02 OB, and I did my own oil changes, etc., the phase 1 engine had the oil filter on the driver's side, while the phase 2 moved it to the passenger side. Obviously major changes to the block were done as well.

My 97 OB Phase I has the oil filter on the passenger side...

 

Commuter

Now I know the Phase I DOHC engines were interference with respect to valves vs. valves (get the cams on one head off-timing to each other and the valves will slap each other), what about with respect to valves vs. pistons, if timing belt breaks, pistons will slap valves... for either Phase I or Phase II?

so change those timing belts on time.

Does the phase II head use solid lifters?

unless there are versions out there I am not aware of.

Phase II isn't supposed to be interference, and the timing belt interchange was extended to 105K miles in '99 on the Forester and in '00 on the rest of the line. In '00 platinum sparkplugs were also dropped as standard equipment on the Phase II (not that that has anything to do with the engine design, just thought I'd throw that in there).

WagonONLY...............Don't Kid yourself. ALL 2.5L ARE Interference! This has been a Regular thread here.

First a reply I received from SOA on an inquiry about my '02 Forester:

 

Thank you for taking the time to contact us. Your 2002 Forester has an interference engine. Therefore, if the timing belt were to break, it would cause further damage to your vehicle. We recommend that the timing belt be inspected at every 30,000 mile service interval and replaced at the 105,000 mile service interval.

 

Then a Reply from Emily at CCR Engines:

 

 

EJ22

'90-96. Non-interferential, definitely.

'97 and 98 are a little fuzzy. Seems that somewhere in the late '97-98 MY there were changes, some of which we haven't seen yet. Late '98, if it looks like a 2.5 SOHC (only 2 timing covers on the front), extremely likely it's interferential. One of these is a 4 month only engine.

'99 EJ22 is definitely interferential. We've done 3 in the last couple of months. 1 year only engine.

 

EJ25

All are interferential, no matter what year, both DOHC and SOHC.

 

EJ20

Interferential

 

 

It's valves that hit pistons. We have part of one piston that was hit so hard that the only thing remaining intact (sort of) is the head (flat side) and what's left of the ring landings. The head is actually in 3 pieces and is being held together by the rings which are "mostly" still in the grooves. The wrist pin was in the oil pan.

 

And the failure doesn't have to be as catastrophic as a broken timing belt or failed tensioner. If the belt is off by as much as 3 teeth, it can and most likely will cause valve/piston damage.

 

If I have ever "preached" maintenance and using Genuine OEM parts, I do it doubly for these engines! Change your oil and never, ever, under any circumstances let them overheat! Use the right octane of gas too. We see burnt exhaust valves in 3 out of 5 engine cores that were replaced for a different problem!

 

Take it for what it's worth, But I Plan to keep a regular check and replacement of my Timing belt.

 

:-)

yeah that whole thread on NASIOC has good info. Also, below is a link to the page I posted pics of the different markings on the phase 1 and phase 2 blocks.

 

http://forums.nasioc.com/forums/showthread.php?s=&threadid=184026&perpage=25&highlight=phase&pagenumber=4