GeneralDisorder

Fuel delivery or plugged exhaust. GD

With a small pick. You fold the brass tang in and they slip out. GD

Have you verified the fan motor is good? GD

I did tell you to send it to Philbin for a reason.... GD

I've seen that happen. Old wiring. Replace the plug with a newer one. It has nothing to do with the pump. GD

Amazon. EBay you might get counterfeit. GD

Get 1217H from Nissan. Their price is about 1/3. Lay 1/8" bead on all raised surfaces. Inside, outside, and around the bolt holes. GD

Yep. We don't touch cylinders unless they are really damaged and have to be oversized. I put forged pistons into EJ255 and EJ257 engines almost weekly and we have NEVER had one burn oil. When I do A "full rebuild" we line hone and deck the blocks. We don't touch the cylinders unless boring them over and then we go straight to 100mm. That goes for other types of engines as well. I have talked to drag racers that would re-ring their big block every 50 to 75 passes and they get faster sealing and higher ultimate compression vs dingle-ball honing. GD

Dude. Chill out. Just paint the backside of it if you feel the need. It's a few scratches that will never be seen on a 12 year old car. What you should have done is ask here prior to buying something you did not need. Now if the engine were going to turn 9k or 10k rippems then sure why not. But on the other hand I've built several that did as well as 4G63's that do and used stock balancers on those so..... GD

There is no need for a fluid damper on a Subaru engine. The engine is internally balanced.

Better to just use the 2.5 with 2000 to 2004 flat top pistons, 770 gaskets, and some torque cams. The dual cam heads breathe better. People's fear of the 25D is founded on misunderstanding and lack of experience with fixing them properly. GD

Just leave the covers off. Get a skid plate instead. GD

The newest iteration has all the sealants being replaced with Three Bond 1217H. This is MUCH cheaper from the Nissan dealer. It's about $15 a tube vs. nearly $40 at Subaru. GD

I've seen plenty of engines that "overheated" and were fine. It's all about the oil and how it was driven and how hot it got. You can't say anything for sure till you open it up and look. GD

The 06 to end of 2.5 SOHC production (11?, 12? something like that) is an AVLS engine. It is not AT ALL compatible. It has different pistons and rods - they got offset wrist pins, and left/right pistons with domed tops that fit the AVLS heads like a key in a lock. You cannot use those engines. Also you should preferentially look for 2005 engines as they had larger oil pumps. The rings are different on 05+ also - they use the same ring as the turbo model piston. GD

I mean carb (what type) or fuel injection, etc. GD

Depends. What induction system are you running? GD

Definitely Exedy. GD

You don't need one. It's only going to increase pedal effort. You arent making enough power to exceed the limitations of the stock clutch so what's the point? GD

Cut everything off flush. Grind the stuck bits with a 1/8" carbide burr till you can slide the axle off. Should take about 10 minutes. At this point it's all F******d so just grind it out and be done with it. They make punches in factorys every day and sell you new ones at the store..... your time is priceless. GD

There is no difference in "case thickness". You can't swap the cranks - well you can, but the machine work to move the thrust bearing runs about $600 if you can find a machine shop competent enough to do it and/or willing to destroy a fair number of cases to learn how. In any case, DO NOT split the case. If you have not done this before you are SURE to end up with a steaming pile of scrap metal after your attempt. And don't think that any old machine shop can do it either. Seek Subaru specific professional engine builder experience (such as myself) if you want to do a bottom end. It is not a simple process. The primary reason you see thrown rods is due to oil consumption from carbon build up in the piston rings. Leading to low oil conditions and resulting in rod bearing failure from oil starvation. The oil pump sizes on the early 251's didn't help. The legacy models had 7mm pump rotors vs the Impreza at 9mm and the previous generation engines (and 05+) at 10mm. GD

5-10 MPG probably indicates problems with rich mixture or timing. It should not be that much different. GD

You don't need a fuel return with a Weber. Just make sure you have 3-5 psi going to the carb. Forget about the return. Just cap it at the firewall. GD

The 96 block has flat top pistons, about a 10cc larger combustion chamber, and hydraulic lash buckets. It uses a year specific valve cover gasket and spark plug tube seal. The 97/98 are basically the same They have 10cc smaller chambers, and dished pistons. But retain the #3 thrust of the 96. 99 blocks have the 97/98 pistons but are otherwise a 2000 block in every other way. 52mm rod journals and #5 thrust. Any of the three can use any of the pistons. Including Phase II (SOHC) flat top 2000 to 2005 pistons which do not crest above deck height at TDC. Thus with these pistons any of the D blocks become 251 blocks for all purposes regarding head and head gasket selection. So the OP need only swap the pistons along with a new set of rings (NPR is good) from his rod knocked Phase II engine into the 96. He can then bolt the Phase II heads back on (after thorough cleaning and inspection) and it will, in effect, be a stock 251. Just with 48mm rod journals and #3 thrust. Which will decrease it's long term reliability, but no more so than any Phase I 2.2 or 2.5. The 48mm rod journals aren't really a problem but the #3 thrust can be on heavy clutch applications. I have seen a number of #3 thrust failures - usually on 2.2T's but have seen others as well. Never seen a #5 thrust failure due to "natural causes". Seen it only from improper rebuild. GD

If the spacer is properly installed into the REAR O2, it cannot cause the P0136 code. The rear O2 does not affect mixture control except on '05+ models. GD