It is actually quite simple to do if you have a corded power drill and grinder.
Parts Necessary:
- 125A Quest Alternator (2000-2003)
- 5/8" washers (total thickness about 1/4"
Tools Necessary:
- 12 mm Socket
- 12 mm Box End Wrench
- 14 mm Socket
- 21 mm (Impact) Socket
- Strap wrench or similar device to hold pulley in place while loosening/tightening.
- 3/8" Drive Ratchet
- 1/2" Drive Ratchet
- 3/8" Drive Air-Ratchet
- 1/2" Drive Impact Wrench
- Power Drill
- 17/32" Drill Bit
- 4" Power Angle Grinder
- Service Manual of some sort
Other Recommended Items:
- Mechanix Brand or similar Gloves
- Duct Tape
- Band-Aids
- Battery/Alternator Testing Tool ($9 at Advance)
- Channel Lock Pliars
The first step to successful completion of this modification is to source a working Quest/Villager alternator. I found mine for $35 at a local junkyard. If you go this route, be sure you have it bench tested at 2 different places. Most reputable junkyards will take back a non-working alternator that they sold as working, if you have documentation that it is not performing properly from bench testing.
Secondly, before I dive into the steps, you need to be certain that you are capable of performing this operation. It was the single most physically painful job I have ever performed while working on any of my cars, and I've pulled motors and complete drivetrains without the help of a lift. The alternator weighs upwards of 15lbs, so you need to be sure you can hold that weight steady for extended periods of time while attempting to line up the bolt holes.
Ok, here we go.
Steps:
1. Disconnect the battery ground.
2. Loosen the tension on the alternator belt by using the adjustment bolt for the idler pulley located to the right of the alternator. If you have access to air tools, you might want to use them for this step. The rotation on the adjustment bolt is opposite of what you would think. To loosen tension, "tighten" the bolt. This brings the idler/tensioner up and removes the tension in the belt. Once the belt is sufficiently loose, slide it off the pulley, while being careful not to damage it. The adjustment bolt is 12mm.
3. Disconnect all wires from the alternator. Be careful not to damage the plastic clip of the harness or the rubber boot on the output cable. You may need to spray PB on the ground wire screw to get it loose. I had to use Channel Lock Pliars to remove the screw, because my screw drivers stripped it. The nut holding the output wire on is 12mm.
4. Unbolt the bottom (long) bolt from the alternator housing. If you have access to air tools, you may want to use them for this step. The radiator hoses tend to get in the way, but you can push them off to the side while you unbolt it, however, be careful not to rip or puncture it.
5. Support the alternator from the side.
6. Unbolt the top bolt. The alternator will want to fall onto the crossmember and damage the pulley. If the pulley has the slightest knick in it, it can cause damage to your belt.
7. Once you get everything disconnected and unbolted, it is time to remove the alternator from the engine bay. However, I learned the hard way that this is easier said than done. If you rotate the alternator so the bolt tabs are closer to the motor, and pull it out pulley first through the gap by the battery, it'll wiggle out eventually. Don't be afriad to put some force on it, but be careful not to damage anything in the process.
8. Now remove the pulley from the Pathfinder Alternator. You'll have to chuck it somehow so it doesn't rotate when you go to loosen the nut holding it on. Do the same on the Quest alternator. The Pathfinder pulley has 5 ridges, the Quest only has 4, so it will not work with the Pathfinder belt. The nut from the Pathfinder alternator will not work on the Quest, and the Pathfinder pulley is narrower at the base than the Quest. Slide the Pathfinder pulley onto the shaft, and slide the 5/8" washers on as well. You'll need enough washers to completely cover the shaft up to where the threads begin, otherwise the pulley will be loose. Hand tighten the Quest nut, and chuck the pulley. Then torque it down.
9. The prep work is almost complete. However, the holes for the bolts on the Quest alternator are not large enough to accomodate the bolts on the Pathfinder. You will have to drill them out using a 17/32" drill bit. However, be sure you cover the open vents on the alternator with duct tape before grinding or drilling on the alternator to avoid metal shavings/chips from entering and potentially damaging your alternator.
10. Once you get the holes reamed out, you'll have to grind down the tabs slightly so the bolts can sufficiently pass through them and have enough threads to hold the alternator in place.
11. Installation is the same as removal, but the Quest alternator is heavier and slightly larger than the Pathfinder alt. Also, be sure you tighten the hell out of the output wire nut, otherwise you'll run into the problem I ran into. You might want to pad your palm before doing this because you'll need to put some serious torque on it to get it to connect properly. Be sure you do not reconnect your battery until EVERYTHING is complete and properly connected, tightened. Did you remember to screw in the ground wire?
The Problems and Tips:
I had failed to sufficiently tighten the nut on the output wire, and when I tried to start the truck, it would arc, and cause the failsafe to kill the electrical system. After a few seconds it would reset, and after numerous tries, I was ready to shoot something. Well, I realized that the nut wasn't as tight as it should be when I started tightening it with the battery connected (oh yeah, NEVER DO THAT), and it sparked like hell and shocked the living crap out of my arm. Have you ever had 14VDC shoot through a steel wrench into your arm? Yeah, it hurts.
Also, when I had first swapped the pulleys, the Quest alternator rolled off my workbench onto the floor and bent the pulley. Be VERY VERY careful with the pulley as they are $76 from the dealer, and the dealer is the ONLY place that will sell you just the pulley.
Be ready to have to use plenty of PB Oil if your truck has seen some life.
Nissan likes to put all sorts of little sharp plastic clippies all over the engine bay in the most inopportune spots. I suggest you wear long sleeves and gloves to avoid painful, and often blood spilling injuries. I recieve more little cuts trying to get that damn alternator out than I have recieved in all my working on a car combined...well, except that time I kicked the windshield out of my VW Rabbit....but that's another story.
Be extra careful when tightening down the output wire cable nut, as your wrench can easily slip off the nut and smash your hand firmly against the frame extension rail. I've got a nice black and red thumb and nail thanks to that one.
Have plenty of light to work with. I suggest picking up a 500/1000W Work Light from Sears. They only run about $30-$40 and are absolutely invaluable for any garage or shadetree mechanic.