How do you replace the alternator on a 2004 Mazda 3?

Answer 1

Replacing a alternator on a Mazda 3 2004 technical rating 3 out of 10.

Tools needed.

6"Socket wrench , 10mm socket, 12mm socket 3" and short one, 14mm socket short one and a small flat head screw driver. Also a good shop light.

Start off by removing the engine cover on top of the motor. It just pulls off by pulling up firmly. Second remove the battery cover it is located just to the right of the engine cover. Now remove the negative battery terminal this should be a 10mm bolt. Once you remove the neg terminal wire position it so it can not come into contact with any of the battery posts as you work if there is any corrosion you need to clean it before you reconnect it use a wire brush.

Now move to the bottom of the engine compartment and remove the plastic cover under the engine. There will be three bolts (12mm across the front and two in the back on each side where the inner fender plastic meets the engine cover. Note there is a small plastic finger that attaches this to the fender plastic you will have to pull the fender plastic out to the side while lifting slightly upward on the engine cover plastic.) If its cold outside and the fingers break as mine did from being brittle it is OK the bolts will hold it together.

Ok so now we are almost ready to remove the alternator but first we need to remove the serpentine belt. Back to the top of the engine compartment. looking down on the left side of the engine you will see the belt and pulleys. The tensioner pulley is the one just above the alternator. You will need a Socket wrench and a 14mm short socket. Here is the secret...place the wrech on the bolt in the middle of the pulley adjust it so the handle is tilted forward toward the windshield not straight up and down. This will help allow the belt to slip off the pulley without binding on the socket wrech when you release the pressure. Now push the wrench forward toward the windshield until you feel the tensioner can not move any more and slip the belt off the pulley toward the socket. It is a very tight fit especially when putting a new belt on/off. Now gently let the wrench come back toward the front of the car. You can leave the belt on the rest of the pulleys just move it forward away from the alternator so it doesn't hang up when you remove the alternator.

There are four bolts that hold the alternator to the engine block. One at the top and three on the bottom. Now is the time to take the top bolt out. Look down at the alternator and you will see a bolt 12mm with a 3 inch long socket loosen this bolt and remove it. Next move to the bottom of the engine compartment and look up to see the alternator.

Here we see three more bolts two at the bottom and on just above them. These are also 12mm bolts. You will also see a gray plastic cap on the side of the alternator closest to the radiator. It has a plastic clip that you must depress to get it to open. A small flat head screwdriver will make getting this open much easier. Just use the end to help pry the clip down so you can open the cap. once you open it remove the bolt holding the wire on (also 12mm) Now to remove this wire, this piece has three small clips that hold it to the alternator. one that you will see at the bottom and two just to the left and right of center on the top. Use the small flat head screwdriver to pry them loose and it will pop off to toward the radiator. Put this wire to the side out of the way just loop it around the loom next to it. Just above the area where you removed the plug is another push wire connection. Again use a flat head to help push down the lock clip and pull the plug out.

Now remove the three bolts holding in the alternator. Start with the one at the top. WARNING be very careful when removing this bolt with the socket wrench. The black tube that is in the way is the Oil dip stick tube, you DO NOT want to break or damage it just be careful when you break this bolt loose. It doesn't matter what order you remove the bottom two bolts in just be prepared when the last on comes out the alternator will fall on your face if you don't hold on to it. The alternator will come out the bottom of the engine compartment and you will have to maneuver it a little to get it out but it's not hard.

The new alternator will go in from the bottom just like the old one came out. Once you get it into position start one of the bottom bolts. Move to the top of the engine compartment and put the top bolt in but dont tighten it all the way until you have all the bolts on the bottom started. Now back to the bottom and put the other bolts in and tighten them. Now your done with the bottom bolts connect the electrical connections tighten the nut and close the cover. Move back to the top and tighten the top bolt.

Now grab the belt and put the 14mm socket through it onto the tensioner bolt this time you want the wrench tilted toward the front of the car so you get more pressure on the tensioner,Push the wrench forward toward the windshield and slip the belt back over the pulley (remember its a tight fit) and make sure the belt is properly positioned. Gently release the tension. Now attach neg battery terminal, replace battery cover and engine cover and the cover on the bottom of the engine compartment and you are finished. This entire process took me about 30 minutes. Have fun and good luck.