Replacing spark plugs.

Its about that time to change the plugs out. Who has done it and anybody have a walk through or advice? This will be my first time changing plugs on the boxer motor.

If you have changed plugs before, it's pretty much the same, just that they are on the side of the engine. I haven't done them on my car yet (it's going to be a while before they are due) but on my old WRX, you needed to remove the air intake, battery, etc. to make room, then just remove the coil packs and change out the plugs.

If you haven't done plugs before, keep in mind you have a steel threaded sparkplug going into an aluminum head - you do not want to crossthread the plug into the block.

Originally Posted by DrD123

If you haven't done plugs before, keep in mind you have a steel threaded sparkplug going into an aluminum head - you do not want to crossthread the plug into the block.

Yeah, I did that to my '93 Impreza. Wasn't fun.

I have changed quite a few sets of plugs in the past. I do appreciate the heads up though. Wasn't sure of the best way to go about it. From the top, or bottom? I'll take a closer look in the morning. I'm sure I will figure it out, I don't mind being the Guinea pig and I can pass the word along.

They can get a little tricky to get to, inside the frame rails. Read the service manual for tips on rotating the coil packs for easier removal after hold down bolt has been removed.

Notice white oxidization on bolts in photo below.

I cleaned up bolts, then anti-seized them. Also, added some di-electric grease to the top of the new plugs, along with a small amount of silicone paste for the boot. Also added some anti-seize to the new plug threads.

Got to love the epoxy floor. I got the same stuff for over 6 yrs now and still holding strong. Sorry to sidetrack this thread.

I actually changed my plugs yesterday. Overall its not too bad but a few tools are a must; a universal joint, 3/8 inch spark plug socket, 4 inch extension, 12mm socket to remove the coil packs, and 10mm for the battery. I found its easiest to remove the battery/tray to give you room to work with on the right and obviously remove the intake for the left. The front coil packs I removed with the coil pack wires still attached and then unplugged them once I had them out (not much room to work with). For the rears I disconnected the wires first and then pulled the coil packs. For all four of the packs its easiest (and nearly required for the rears) to rotate the coil pack 180 degrees before pulling them out. Install in the reverse order but make sure the pack properly seated on the plug, it might take a few tries. Some say use a rubber house on the new plugs to thread them but I just used the spark plug socket with universal joint to thread them in. Make sure to put some anti seize on the new plugs to save you a headache down the road and ensure the plugs go in smooth. A torque wrench will be hard to squeeze in to achieve the correct torque but if you thread by hand and then tighten up until snug and another 2/3 a turn to smash the crush washer you should be fine, just take a look at the plug box and it'll make sense. Id also recommend when removing the coil packs to keep them organized (easy to just lay them out in the correct order when pulling them out) Since its your first time it should take you around 3 hrs. Best of luck!

I tried to swap the coil packs in my forester yesterday b/c i'm getting a misfire. Managed to get the wrench stuck between the engine and frame rail and got sufficiently pissed that I gave up and had taken to the dealership. I suck.

It's great that you guys are posting this. I've changed a ton of plugs in my life, but these subaru boxers are unique. So we need a 3/4 universal joint? Isn't there an extension combo that fits or does the partially removed plug force the socket against the frame?