I'm in the process of changing our my motor as well. I've been trying to loosen up the rear wiper arm with PB Blaster, but haven't had any success yet. I thought about cutting the shaft, but I'd like to get the core back for the old motor. I was also hoping to use the old arm, but things aren't looking too good there either, even if I am able to remove it. Oh well, at least it's still cheaper than having the dealer do it.
Let me know if there's anything else I need to look out for in the swap!
Well, it doesn't look good for the wiper arm if yours is like mine, but the good news is I didn't have to damage the old wiper motor head to remove the arm.
First off, start from the outside, all the interior side bolts must be in place and tight so it doesn't move around while your working. (I found this out quickly.
I used a hack saw blade (a dremmel tool might work) to make a cut parallel to the motor shaft and directly above it. Once I got down to the teeth you could see them at the bottom of the cut. Tap in a screwdriver gently, and it may take some prizing and tapping, but the aluminum is weak and should break off in a chunk large enough to free up the arm to the point it can be pulled off easily.
Now once the arm is off, if it was that tight the nut holding on the motor probably won't be any better. I used a deep well socket. It came off, but it took great pressure applied very carefully. That nut isn't the best quality either, and you need it for the replacement. It should come off, just be careful.
Now there is a washer and a odd shaped spacer that makes up for the curve of the window. That can come off too, but I highly recommend leaving it on there as it doesn't go back easily and it only covers the rubber seal. It doesn't need to be removed, but if the buildup is really bad (as was my case) it seemed to help some.
Take off the interior side cover, and only 2 fasteners should still be holding it to the glass, and of course unhook the electrical plug. One fastener looks like a star shape and can be taken off with a socket. It turns correctly from the outside, which is a flat headed smooth button. It is backwards from the inside, so turn it to the right. Now that is free the motor and cover together should be able to come through. It might take a good bit of squirming and wiggling it around to loosen it up so it will come out.
Once it's out of the window, 2 small screws hold it into the plastic cover. They are 5mm socket I think. Keep the rubber spacers from the motor, they were not provided on mine, both have washers as well, note how these come off.
Going back on is just a reverse order of taking it off. I added silicone sealer to the 2 places where fasteners pass through the glass, yet to see if it's watertight but I believe it will be.
Good luck, wasn't as hard as I thought it would be, just took some careful thought before doing. Cutting the arm was difficult for me cause I didn't want another part to replace, but once I got inside it I clearly seen I wasn't going anywhere till it came off. I probably provided more info than you wanted, but if this gets searched for whoever is looking will have a more complete set of instructions.