OEM Shortblock Markings:

1. The "BBBB" in pic #1 of your 2nd post refers to the cylinder bore sizes and which size piston they used (one letter for each cylinder). There's A and B bores from my understanding (most blocks are a mix of A's and B's). That's the only marking I know pictured. -Deuce Cam

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OEM Shortblock Markings:

1. The "BBBB" in pic #1 of your 2nd post refers to the cylinder bore sizes and which size piston they used (one letter for each cylinder). There's A and B bores from my understanding (most blocks are a mix of A's and B's). That's the only marking I know pictured. -Deuce Cam

Image Link

The numbers to the left of the piston sizes 33322 are the main journal sizes.

I have a factory replacement shortblock and my main sizes are 11111 and my pistons are all B size (smaller). This seems notable, as I have never seen or heard of another where all these sizes are consistent.

 

Removing the Pistons:

1. Remove the rear service hole cover. It is held on by 2 screws which require a #3 Phillips head socket (or screwdriver) to remove. When removing these screws, press in on the ratchet to prevent the bit from slipping out of the screw's head. If you end up stripping the head, use a drill bit and an easy out as described in step 2 to remove the screws. Note that the rear service hole cover uses an O-ring to create a seal against the shortblock housing (Picture 2).

2. Remove the rear pan cover. It is held on by 6 screws which require a 4mm hexbit socket (or Allen wrench) to remove. If the screw head strips, drill a 1/4" deep hole through the center of the screw with a 7/64" drill bit. Use a #2 easy out and an adjustable wrench to remove the screw. To get the easy out to bite into the screw, gently tap it with a hammer from behind before applying any torque with the wrench. The pan itself is held on tightly by liquid gasket, but will come off easily with the right leverage. I used a nylon pry bar to remove the pan without damaging it (Picture 2). Once the pan is removed, you have access to the service hole plug for cylinder #3. (Picture 3).

3. Remove the 3 service hole plugs with a 1/2" drive breaker bar and a 14mm hex bit socket. Lean on the opposite side of the block that you are pulling from as these plugs are difficult to loosen. Note that these plugs are assembled with liquid gasket and a steel ring gasket. Use a putty knife or razor blade to gently remove the steel ring gasket if it is stuck to the shortblock (Picture 2).

4. Rotate the crankshaft clockwise with a 3/8" drive ratchet and a 22mm (or 7/8") socket until the piston pins are visible through the #1 and #2 service holes at the front (Picture 2). Remove the retaining clips with a pair of needle nose pliers (Picture 3). Be careful and make sure you have them held securely before removing them. If they fling off your pliers while inside the block, you'll be fishing them out before proceeding.

5. Here is where methods can vary. The 07 STI Service Manual says to remove the piston pins from service holes #1 and #2 using the piston pin remover (Special Tool 499097700). Repeat step 4 again for the rear service holes. Then remove the piston pins from service holes #3 and #4 using the piston pin remover. The helpful links in the first post of this DIY show some fabricated tools that can be used instead of the piston pin remover. The pistons should remain in their cylinders so long as you do not rotate the crankshaft a full rotation after removing piston pins #1 and #2. The 07 Service Manual states that the pistons should remain in the cylinders when the block is separated. I'm going to use an alternate method starting in step 6. You might encounter some of the problems I encountered even if you follow the Service Manual, but steps 6,7, 8, and 9 will help you solve them.

6. Take a long and thin flat head screw driver and put a piece of electrical tape over the tip. This will help protect the shortblock components from scratches. Guide the screw driver through service holes #3 and #4 to reach the back of pins #1 and #2. Make sure that the flat tip of the screwdriver is seated securely against the piston pin and not the retaining clip. Tap the back of the screwdriver with the palm of your hand to force the pins out the other side. If the rods prevent you from guiding the screwdriver through, you may need to turn the crankshaft. Double check that the pins you are removing are still lined up with the service hole if you turn the crankshaft. Also, turn the crankshaft slowly if you've already removed a pin because that rod will be touching the cylinder wall. If you feel that it is binding, rotate it gently counterclockwise. Don't force the crankshaft if it doesn't want to move. Once pins #1 and #2 are out, repeat the same process for pins #3 and #4 after removing retaining clips #3 and #4. Mark the pins with a sharpie so that you know which cylinder/piston they came from. Depending on how you do this, you may run into a few issues and find that pistons start popping out and need to be removed. I removed all 4 of my pistons before separating the block, but this is not absolutely necessary. Steps 7, 8, and 9 cover the different scenarios you may or may not encounter when removing the pistons.

7. When the crankshaft is rotated during step 6, pistons may start popping out. This happens if the rods catch the piston after the pin was removed. Carefully pull the piston out if this happens (Picture 2). Mark the piston with a sharpie to identify which cylinder it came from. Wrap the tip of the rod with packing material to protect the cylinder walls as you rotate the crankshaft (Picture 3). If you wrap the rod too far up, it may pull into the crankshaft and feel like it is binding.

8. You might encounter a problematic piston. This one was sticking out enough to allow the ring to protrude. However, it was tightly fit to the bore and it was not exposed enough to allow me to pull it out by hand. I tried to rotate it slightly so that the rod could push it out the rest of the way, but this didn't work either. I finally resorted to inserting a flat headed screwdriver tip into the top ringland gap while supporting the piston with my hand on the opposite side. I also put a rag between the screwdriver and the shortblock surface to prevent any scraping or damage to this surface. I very carefully and slowly maneuvered the piston out with leverage. Step 9 shows a better way to remove a piston like this.

9. You might encounter a piston that does not want to come out at all. In this case, the rod and piston align so well that the rod will not push the piston out when the crankshaft is turned. To remedy this, take a rag or cloth and clean the service hole for this piston. Then take 2 to 3 rags and wind them up so that they can fit into the service hole. Stuff 2 to 3 rags in the service hole towards the back of the piston and then turn the crank. The rod can't align with the piston when the rags are in the way and it will force the piston out.

 

Separating the Block:

1. Make a cardboard template of the bolt pattern for the side with cylinders #1 and #3. The service manual calls this the RH or right hand side. Prepunch the holes with a Phillips head screwdriver. The template will make reassembly easier. Remove the 6 bolts (Picture 2) with a 1/2" drive breaker bar, 1/2" to 3/8" drive adapter, socket extension, and 12 point 12mm socket. Make sure the extension and socket are long enough to give the breaker bar good clearance to the machined surface. The bolts are not easy to reach and remove once they are loose. Use a telescoping magnet to pull them out (Picture 3). As you remove the bolts, punch them through the template (Picture 4).

2. Make a cardboard template of the bolt pattern for the side with cylinders #2 and #4. Add the "Underneath" and "Behind" locations to the template. The service manual calls this the LH or left hand side. Prepunch the holes with a Phillips head screwdriver. The template will make reassembly easier. Loosen the 10 bolts (Picture 2) with a 1/2" drive breaker bar, 1/2" to 3/8" drive adapter, socket extension, and 12 point 12mm socket (Picture 3). On the bottom left bolt, I recommend using a 6 point 12mm socket instead of the 12 point since it gives you more contact surface. Make sure the extension and socket are long enough to give the breaker bar good clearance to the machined surface. Do not loosen the bolts more than 1 turn. Do not remove these bolts.

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4. Turn the shortblock on its side with cylinders #2 and #4 facing up. Locate the screw underneath and remove it with a breaker bar, swivel adapter, and ...

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6. Place a couple pieces of cardboard on the inside of the shortblock so that the jack base and crown will not damage the aluminum surface. Use the OEM jack to separate the 2 case halves. WARNING: You only want to start the separation. Do not continue turning the jack screw once you see a thin gap between the metal. Once you have this thin gap, take a rubber mallet and tap the metal near the seam at the front of the two case halves to help loosen the liquid gasket. Be careful not to hit or damage any machined surfaces. Optionally, place cardboard against the metal to dampen the blow of the mallet. Then remove the jack.

7. Separate the two case halves by lifting straight up on one side. If you start lifting and the case halves get ****ed to one side, push them back together and try again. You can take some precaution here and have a friend place some cardboard against the metal where the rods are going to fall. I let mine fall and they were fine, but it's still a good idea to protect the surfaces.

 

Separating the Block:
This section shows how to separate the block.

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Here's a method that worked well for me.

1. Take a section of broomstick, or a wood dowel, with a diameter a bit smaller than the wrist pin, and a couple inches longer than the cylinder diameter.

2. After removing all the bolts which hold the case halves together, stick the broomstick into one of the cylinders, say #1, and push it through the connecting rod little end, like you're installing a piston. Push it through far enough so it will catch on the cylinder wrist pin holes on either side of the cylinder.

3. Then turn the crank to put some preload tending to force the the case apart.

4. There are a few projections around the case which can be tapped on. I used a heavy hammer and a short piece of 1x2. With the force from the crank, and the tapping, the case started to split after a few taps.

5. When I saw the initial split, I put the broomstick in a cylinder at the other end of the engine, like cyl# 3, turned the crank to put some pressure, and tapped.

6. After that end of the case started to split, I separated the case halves by continuing to tap around the case, and just generally pulling the halves apart.

With this method you avoid any sort of prying on the case halves, which risks marring the mating surfaces of the case halves. Anyway, this worked well for me.

 

Remove the Crankshaft, Bearings, and O-rings:

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2. 1.5mm Allen, 3mm Allen

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Remove the Rods from the Crankshaft:

Top of the 2's on the ring faces the front. 4's on the rods face back.

 

The "BBBB" in pic #1 of your 2nd post refers to the cylinder bore sizes and which size piston they used (one letter for each cylinder). There's A and B bores from my understanding (most blocks are a mix of A's and B's). That's the only marking I know pictured.

 

That's a pretty cool idea for separating the block without upsetting the metal. I'm going to try it a different way just for the sake of experimenting, but I'll come back to yours if I can't find an alternate method.

 

Sounds good. Let us know how it goes.

 

sorry, but this was too awesome to let die... LIVE!!!

 

Really good stuff man! I agree with the above this is to good to let die.

 

very nice

 

Excellent write up. I am in the process of doing this right now due to failed bearings. My bad, running US Spec Castrol 5w-30 led to this.. I suppose driving at the limiter for miles on end is not a good combo on this oil.. Need to run the ACEA A3 spec stuff from now on..

 

I just ordered my 14mm hex socket from NAPA for teh wrist pins to start my disassembly. This write-up is exxcelllllentttt!!!! :tup::tup:

 

Will use this with the FSM to help my brother pull apart his engine this week!

-Don't let this post die, people!

 

Friends, I need to know if the metals of a boxer engine (subaru impreza ej18), are equal?. Bone, if the metals or block bearings right or left are exactly alike, so that it can exchange. Greatly appreciate the response and even better a photograph to be quiet.
Thanks, greetings from Chile.

 

When I removed my piston pins, I bent a metal clothes hanger to have a handle and hook on the end. Wrap the end in tape as not to scratch anything. My lady friend called it an abortion tool. Works like a charm.

 

why it has two different parts? 703 and 702

sorry

 

Awesome how to write up.

Does anyone know the meaning of the letters following the engine size? As in B257C?

 

Awesome write up. Helped me out alot!