How to change the alternator on a mid range XJ
The alternator is located in a low place on the Xj engine. This makes it susceptible to damage from mud and water. It is also annoyingly hard to get to.
Begin by removing the battery and the battery box. The battery box is held in place by three nuts that are likely to be very rusty. Soak them in some kind of oil (I use PB blaster) to reduce the chance of breaking them.
Next remove the air box so you can loosen the belt. The belt tension is adjusted by moving the power steering pump. You have to loosen the two bolts on the back, the hinge bolt at the top and the nut on the adjuster slide. Then, you can turn the adjuster screw to loosen the belt.
Next remove the wires from the back of the alternator. The field wires are held by two 10mm nuts and two 7mm nuts.
The output wire has a ten MM nut. It may be easier to leave it until you get the alternator unbolted.
The alternator is held to the bracket by a short bolt at the bottom and a long bolt at the top. Remove the bottom bolt and loosen the other bolts that hold the steel bracket to the timing cover. You may not have to remove them. Just loosen them. Note that some of these are 15mm and some are 9/16. Those that attach to the engine are SAE (9/16) and those that attach to accessories are metric (15MM)
Now remove the long upper bolt. There is a certain spot where the fan can be placed that will allow the bolt to come out. Two 15MM wrenches.
Now the alternator can be removed from the bracket.
The next trick is to get it out of the engine bay. The original designers made a nice cut out in the unibody to clear the alternator. However, a later engineer filled this space with freon lines.
If you don’t have AC, the alternator will just slip out. If like most, you have AC, then you have to get more creative. If you are brave, you can bend the lines a bit to make room. However old rusty metal lines may break.
On my Jeep, I can lift the engine just slightly and the alternator will come out. This does not work on others; even the same year.
On those, you will have to remove the entire bracket from the block. You have to remove and install them in separate pieces also, they won’t fit bolted together.
One you have figured out how to remove the alternator and get the new one in place, loop the belt over the pulley and install the two bolts.
Reattach the field and power wires. Reinstall the battery. Tighten the belt.
You may want to test run the engine and tighten the belt before reinstalling the air box.