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DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

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Old 11-30-2013, 10:43 AM   #1
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Arrow (How To) e46 Alternator Upgrade / Replacement without removing Fan

After upgrading all the pieces of my Bimmer's stereo and putting a 15" Kicker in the trunk running 1200 watts... I was having some amp cutouts at high volume. So, what do we do? Well, we have to upgrade the alternator you know! The stock alternator is 140 Amp... I went ahead and bought a 200 Amp from:


Click on the BMW section, then scroll down to one of the ones that say "200 AMP" in red on the picture. The specific item page will tell you if it is compatible with your car.

This should work on any of the following BMW e46 groups:
BMW 316 (316i, 316ti)
BMW 318 (318i, 318ci, 318ti)
BMW 320 (320i, 320ci)
BMW 323 (323i, 323ci)
BMW 325 (325i, 325xi, 325ci, 325ti)
BMW 328 (328i, 328ci)
BMW 330 (330i, 330xi, 330ci)
and BMW M3

1 - - - Attention! The FIRST STEP is to unhook your positive battery cable in your trunk! If you do not do this, you may accidentally touch the positive alternator lead to the chassis and short stuff out, melt stuff, blow stuff up, get a shock...

2 - On the right side of your engine compartment is a large air filter box. Remove the sensor connector, and the intake passage hose from the top of this. Then, take out the 10 mm bolts on the right hand side.

3 - Switch to a 13 mm socket and loosen the two bolts on the Power Steering reservoir. Remove it, place the bolts somewhere safe, then lay the whole reservoir to the right side where your air filter box was.

4 - Now we will remove the cold-air snorkel (that plastic thing on top in front of the fan). Pry up the pins and plastic rivets gently with a pry bar.

5 - Loosen the top alternator bolt as far as it can go with a ratchet and then a wrench.

6 - tap the pully outward. Then push the bolt all the way out to the fan.

7 - Now work on getting the bottom alternator bolt out as far as you can.

8 - Somewhere between 6 and 7, you may want to loosen the serpentine belt and get it off of the alternator pully, in order to get it out of the way of the bottom bolt. You will do this by putting a breaker or long ratchet on the fake bolt that turns to the right to loosen the belt. This will take a 5/8 socket.

9 - Take the wire harness off the back of the alternator, along with the positive lead.

10 - Get your new alternator lined up with the bolt holes.

11 - Reinstall wiring harness and positive lead.

12 - Tap bottom alternator bolt back in place until you can turn it and the thread catches. Screw this bolt almost all the way in, but leave it loose enough to be able to bring the top bolt holes in place.

13 - Use the pry bar again to loosen the belt and get it back on the alternator. This will pull the top bolt holes into place.

14 - Put the top bolt and pulley back in place. Make sure the pully is swivelled to lign up the divot and notch that are between the pully and the alternator.

15 - Tighten the top bolt and then tighten the bottom bolt.

Finish by re-assembling everything backwards... I believe in you. You can do it!

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Old 11-30-2013, 01:51 PM   #2
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Thanks for sharing but....

(this was the look on my face watching the video)

....why WOULDN'T you want to remove the electric fan?

It is LITERALLY the easiest thing to remove before tackling the alternator!
Pry off the two rivet pins, unplug the electric fan's wire harness connector and the entire electric fan assembly/shroud just lifts right up out the engine bay.
It takes about 20 to 30 seconds to do.

In fact with the fan still attached he is exerting more energy and spending time removing the alternator (WHILE risking damage to a $400 fan assembly)
than had he just spent the 30 seconds removing it.

Now the mechanical fan I can see where NOT having to remove that fan to get to the alternator would be a decent trick.

It would be more than decent it would be magical since the mechanical fan requires expensive special fan tools and alot of patience.

Last edited by delmarco; 12-08-2013 at 07:10 PM.
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Old 12-01-2013, 09:00 AM   #3
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(How To) e46 Alternator Upgrade / Replacement without removing Fan

Step #1 should read "disconnect the NEGATIVE cable from your battery."

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Old 12-07-2013, 05:08 PM   #4
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I cringed at the 7:11 mark where he put his foot in the engine bay and stepped on his alternator, crushing the hoses and causing stress to the part that the hoses go to. You can definitely see where the hoses crush and pull.

That being said, good job.
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Old 12-07-2013, 05:20 PM   #5
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(How To) e46 Alternator Upgrade / Replacement without removing Fan

wow at "guess ima just have to get in mah engine bay" steps on EVERYTHING. lol

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Old 12-07-2013, 06:42 PM   #6
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(How To) e46 Alternator Upgrade / Replacement without removing Fan

I cringed way before the foot made it under the hood...I'm scarred for life.

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Old 12-07-2013, 07:07 PM   #7
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It looks like he pried up on the MAF connector clip @ 1:00, then cut to closeup and claimed his was missing. I assume because prying up is the wrong way to disconnect that clip and his went flying so he tried to play it off as though he didn't have one to begin with. Also the stock alts are 120A not 140.
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330xi, alternator, diy, e46, install

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