I noticed that the oil pressure light came on when I was rolling backwards in neutral a couple of weeks ago. At the time I freaked out, and I damn near cracked a rib trying to shut the card off. I then gave it a thorough going over and everything seemed ok, still hesitant to turn the car over I googled it to see what I could come up with. I eventually narrowed it down to the oil pressure switch (I'd call it a sensor but every one seems to call it a switch). Next time I found myself near a local dealer I ordered one ($32) and picked it up a couple of weeks ago. I finally got around to putting it in today (I have kids). I had looked around the web for a good overview of what I was in for and was surprised when I didn't find one. There may be one here already that I missed, but in the event there isn't I figured I would make one. I've used enough of them, I suppose it's my turn to give back...
Of course there is a caveat. While looking it over I thought I could get the switch out without removing the alternator. It's true, it was possible, but after having done it I would remove the alternator if ever I needed to do it again.
What I needed:
Torque Wrench (I'd never consider it optional, especially on engine work)
regular socket wrench(should never loosen with a torque)
24mm deep socket
17mm standard wrench (not a socket)
about 9 inches of extenders (if not removing the alternator, but you should)
needle nose pliers
Rags (wasn't oily or dirty, just always handy)
Had I taken off the alternator I would also have needed an additional wrench/socket. In my experience these are usually 10, 12 or 14 mm.
Here is the overview of the engine:
Here is a closeup on the left side of the alternator:
Here is the part after it came out:
This is actually two separate pieces. The part with the tab is the sensor (24mm deep socket). Had I taken off the alternator I would have noticed and separated the actual sensor from the anchor (17mm) leaving the anchor in the block. Since I had already removed it and the part was out, I separated them and screwed the sensor into the anchor and then screwed the anchor back in. There is an aluminum washer in between the anchor and the block. That's what I used the pliers for.
Since I had removed them without taking off the alternator I figured I would try and get them back on the same way and was able to by tightening the unit by hand before applying the torque wrench.
The torque on the sensor is 18lbs. Here is a handy site, this is a link to the EJ25 block version:
I let it run for about 20 and gave it some good revs, no leaks thus far, I'm going to have to check it pretty regular for a couple of weeks since I wasn't sure if the anchor bolt has the same torque as the sensor. if anything goes tragically wrong I'll update.