2001.5 s4, 150k miles. Ok, so just after a fresh battery replacement, my alternator decided to take a crap while i was driving home (voltage had been low all day with car running, then it finally died on freeway). So i got the car up in the air and removed everything thats in the way. Here is where Im at. My question is what is the procedure for removing the alternator from this point? is it as straight foward as it looks? do i just remove the two bolts holding it in and a few light taps with the rubber mallet? Do i have to remove the serp belt? If so how? Im in the middle of the job so some quick feedback would be greatly appreciated. If anyone has a write up for this (s4 NOT a4)that would be excellent. Thanks

 

Which direction do i turn the tensioner nut to loosen tension? I know noob question, but This is my first audi (s4 at that) and my first time replacing anything ran off the serp belt so im scared to touch anything im not 100 percent sure i can put back .

 

Dentensioning is clockwise, I think. It'll be obvious if it isn't.

Remove the negative cable from the battery.

Remove the belt.

Reach around back and feel for the wire clip you'll need to remove and for the ground cable nut you'll have to unscrew. There's usually a plastic cap over the stud the ground cable goes on, so you'll have to slide that off first. Remove the two big bolts holding the alternator in and wiggle it out. You'll need to remove the IC hose and probably have to rotate it a bit to maneuver it out.

Get a replacement alternator of the same type (Bosch or Valeo). If you're not sure which one you have, look at pictures on online suppliers of reman alternators and pick the one that matches. Advanced Autoparts has reman alternators that are guaranteed for life. If you get one there, just make sure there are no loose polishing stones left banging around in the alternator (ask me how I know).

The new alternator will likely come without a pulley so you'll need to switch the old pulley to the new alternator. If it comes with a pulley, make sure it's the exact same kind before leaving your old alternator behind.

Install is reverse of removal - just wiggle it in, reconnect the back cables, then install the two bolts, then belt. One hitch - the new alternator may be a little (1 mm or so) too thick to fit into the hard mount the bigger bolt comes out of, so you may have to file off a little bit of aluminum from the new alternator to make it fit. Don't take off too much or it'll be loose. You may have to try and fit and remove and file a few times, which is very annoying (ask me how I know). It should fit in very snuggly. You can put a wooden board against the alternator and pound on the other end with a hammer if you need to.

Good luck!