Anyways we removed the engine and replaced all "wear" items which also included all oil seals. The similarity between the 2.2 and 2.5 NA blocks are surprising. I dont know for sure if this is applicable to our engines but I would assume so - Edit: this confirms the 2.2 has the same problem http://bbs.legacycentral.org/viewtopic.php?t=33837
If you havnt seen it the rear main seal is just like the cam/crank seals only siginificantly larger. I would guess it has a 5 inch diameter? I feel that Subaru made a mistake in the implementation of the oil drain for this seal which could cause all your oil to spray out the rear of the engine after only 10 minutes of driving! I will try to explain -
The seals are pressed into a machined ring and oil usually enters from around the shaft or from a small hole near the top. The oil exit is usually on the rear face of this machined ring. On the rear main seal however the oil drain is on the outer surface of this ring. If you install the rear main seal and push it completely flush with the inner face of the ring instead of the outer surface of the block you will completely block this drain!
For those of you who have taken an engine apart and cleaned it you know that its normal for the car to smoke for the first couple minutes after starting. It was 4AM and I decided to test drive to Dennys up the highway .... it turned into what I can best describe as the "Spy Hunter" game. We covered all of highway 405 in LA with a thick cloud of smoke and left a visible trail of oil! When we stopped in the parking lot a pool of amber colered oil collected under the car. Nothin was open so we went in to eat some breakfast until the grocery store near by opened. We bought 3 quarts of el cheapo oil and refilled the car so we could drive back home, spy hunter and all.
It was obvious the leak was from the rear of the engine and the only spot back there it could be was that seal. We took the transmission out instead and the area behind the flywheel was shiny with fresh oil. It was EXTREMELY hard to get the seal out since it was so deep. I eventually used a drywall screw to stick into the seals face and pull it out. Tough lesson to learn but it did give us the chance to fix his leaking exaust and tighten up the shifter (5 speed).
In the end we removed nearly the entire power train not including the rear differential (we also did brake work). One thing I learned is that an Impreza fan is really also a Legacy fan and vice versa. They are essentially the same cars in different trim.
In conclusion when installing oil seals they should be only slightly below flush with the face of the block/head and not hammered all the way in.
Edit: Here is a picture [/img]http://i16.tinypic.com/72q037q.jpg
