I recently changed my alternator in my 2001 pathfinder. It was a bit harder than anticipated, and I wanted to pass along some of the things i've learned on the process. The job took me about 2.5 hrs for removal. This was mostly because of the super tight space that you have to work in to remove some of the bolts, and the amount of disassembly required to get the alternator out of the hood area.
I took the alternator down to Autozone for a free alternator test, and it passed the tests they performed. I however decided to purchase a new one ($132 dollars for a remanufactured, guaranteed for life alternator) and put it in, rather than put the old one in, and have it fail later. I also suspected that I may have an intermittant issue that wasn't appearing in the test.
According to my research on the internet, an alternator should last you about 120,000 to 150,000 miles. Mine was at 155,000 miles, and therefore it had already outlived expectations. This alternator lifespan will vary based on the conditions that it is exposed to, dirt, heat, cold etc.
- Disconnect the battery - both positive and negative terminals and remove battery from holder - For some of the connections, this is the only way you will reach them, and also the way that you can manover the alternator out of the under hood area.
- From underneath - remove the plastic shield underneath the front of the car. It is held on by a six to eight 10mm bolts.
- Remove the upper radiator hose -- MAKE SURE THE VEHICLE IS COLD and there is no preassure on the coolant system, otherwise you could sustain burns.(some coolant will drain out, be ready to catch it.).
- Also free the cable from the support bracket on the top of the platic fan housing. (the bracket can be opened from the side closest to the engine.)
- There is an overflow hose that is also clipped to the fan housing unclip the hose and move it out of the way.
- From underneath, push in on the clips and the lower half of the fan housing will come out of the bottom.
- From the top - remove the two bolts (again 10mm ) holding the upper part of the fan housing and you should be able to work it out from the top. You should now have good access to the alternator.
- Loosen the belt tensioner on the main serpentine belt (from below) and remove the belt.
- Remove the belt tensioner (idler pully) itself with the three 14mm bolts that hold it in place. This will help you later when you are trying to slide the alternator out.
- There are two mounting bolts on the alternator, a long one through the alternator and a second on the "dog ear" of the alternator.
- Once the alternator is movable - you can get at the battery cable post 12mm and 10mm bolt / nut with a short wrench. I would highly reccomend using a ratcheting wrench - I love these wrenches!
- The alternator wiring harness can be removed by pressing in on the locking clip. The clip is toward the back of the alternator, and should be easy to press and wiggle free.
- Most difficult is the wiring harness support bracket. A short 10mm wrench can get to it. -- if this is not possible for you, then from underneath, there is a space that you can get your hands in, just infront of the axle that will get you to the back of the alternator. Use a standard screwdriver to slide the metal tab of the support bracket out of the plastic tie that goes around the wire loom.
- The alternator is now free but will have to be manipulated forward so that it sits below the fan. Once there - you can reach down from the top, and pull the alternator into the larger gap between the fan blades. While rotating the fan, bring the alternator around with it to the top and it will come out. To reinstall -- do everything in reverse. I would recommend replacing the belt so you don't have to do this again.