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Discussion Starter · #1 · (Edited)
Well my alternator went out so I had to replace it. I have a 2004 IS300 sedan. I haven't saw any DIY on it so I decided to make one myself. I lack the my tools list that I used for this because I did this in a rush I had work later that day so I needed my car. So here we go.

Tools:
14mm socket
12mm wrench
10mm socket
extension
6mm female Allen key
Jack stand and Jack
and screw driver depending on what Intake you have.


First off disconnect your battery (if you battery is dead then this is a good time to charge it either at home if you have a battery charger or take it to autozone its free.) and then take out your intake for more room to work on, also your under body cover. Jack up the pass front side or the whole front of the car up, your choice. Also place bricks or stoppers behind you back tires so the car doesn't rock back and forth. E-brake up and check to make sure your car is secure by shaking it. Safety first.

Then remove the accessory belt by pulling down the tension belt. As seen in the picture. Do not try to remove your alternator with the belt on. There is too much tension on the alternator and you might strip out the threads on the bolts that's holding the alternator. (I did this before on my old car.) As seen in the picture.


After that you can unplug the alternator and remove the top bolt right next to it as seen in the picture.


Then on the bottom shot of the alternator you can see the bottom bolt. Once you take off the nut you can use an Allen key (female end) and take the bolt/stud off all together. This makes removing the alternator a lot easier. If you don't take off the stud then you can remove the radiator fan by removing your top radiator hose and I believe 6X 10mm bolts holding it on to the radiator itself. Then you have enough clearance to remove the alternator. Just a couple of extra steps.


This is what the bottom alternator bolt looks when its off.


On the alternator when everything is off.


The only thing you need to swap out is the bracket from the old to new alternator.


Reverse the process and make sure the accessory belt is on correctly. This shouldn't mess with any of the tension on the belt if installed correctly. Cross your finger and hope your car start lol mine didn't the first time.

My issue was that the bad alternator messed up my battery. A couple of cells died in the battery. When the car was jumped it was reading 14.4volts and with the car off it stayed pretty constant at 11.6volts after 5min of rest. My battery was only 1.5 years old so I didn't suspect my battery at all. The alternator was bad either way. Under crank it dropped a low 4volts. That's a no no. Took it in to autozone since there was a 3 year warranty and everything was good afterwards. Just wondering if anyone hears a whining sound from their alternator on other is300. I am having that issue if anyone can give me their input on the sound. thanks. I hope this can help anyone looking to change out their alternator. GL.
 

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Nice DIY! This was well needed and glad to see it done. I just had one question, when you take the bottom mounting nut off the long stud, you're saying that stud that the alt rests on has a torx head and the stud can be removed with a torx socket? I've removed the alt many times and usually pulled the top rad hose and 6 bolts that hold on the fan assembly just enough to get the alt's pulley to clear the fan shroud. Not really hard, just a pain for the few extra needed steps. Anyways, nice write up and should go well with my detailed DIY Complete Charging System diagnostic so members know if it's bad and then come here:approve:+repz
 

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Discussion Starter · #5 ·
yeah its a torx stud but i used an Allen key to remove it. Also I used pb blaster to help me loosen all the bolts and nuts and I edited. fix
 

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please oh please oh please!!im an idiot im trying to turn the top alt bolt to the left and it not comming loose and starting to strip. you tun it to the left rite??? im such an idiot
Yea, it's counterclockwise to loosen. You're using a 14mm socket? I'm guessing the tests i showed you to do proved it is bad?
 

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Discussion Starter · #9 ·
its on an odd angle so you have to make sure your socket it on all the way. Use a 6 wall instead of the 12 wall (i think) socket, it'll have less change of stripping the bolt. Also use PB blaster to help it out if its rusted shut. GL
 

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I did this today, but it took so long Im not sure everything worked out perfectly. The car started and the voltage was back to about 13.5 or so. But it started to squeak for a while then everything came back to normal before I shut the car down. Anyway, great writeup. I also went the route Jasonm4 mentioned, by taking off the bolts to the fan shroud. I didnt want to attempt any of that long bolt removal. I dont have the tool for that and didnt want to risk stripping anything. The hardest part for me was the belt tensioner. That sucker was hard to figure out that it was actually moving. I saw a guy's youtube video explaining to put a socket wrench on that sucker with the handle straight down and to pull to the passenger side. Worked then fan shroud and getting the old Alt in one of the triangles of the shroud and then out the top. Then putting the new one back in I had to remember how it was positioned. I kinda remembered the plugs were all facing down for some reason. But they are on the top side when on. Then putting the belt back over the pulley was even harder than taking it off.
Anyways, I have to top my radiator back off, by a quick trip to the store for some distilled water and my leftover red antifreeze in the garage and Ill see how that puppy works. My car though, its on its last legs I think.
 
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