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Discussion Starter · #1 ·
Recently replaced the alternator on my 2005 325i and wanted to post a few comments, tips, etc. on issues I face and/or have seen others mention.

Important caveat: This is meant more of a summary of some of the issues you might run into. I will include links in a second post that might be more helpful as step by step guidance. So, for example, don't be pulling parts off without disconnecting the relevant wires, the battery, etc., which I mostly ignore below. As always, YMMV.


1. Getting to the Alternator: Removing the Air Filter Box, Intake Air Duct and Fan/Fan Shroud

Found some YouTube videos that were very helpful and showed what an easy job this would be. Unbolt and remove the air filter box and the intake air duct, unbolt the fan shroud and pull it and the fan out. Easy. (Note: the fan shroud screw on the car's right side is a Torx 25, not a Phillips head screw or an Allen Wrench/Hex Key, no matter what the person before you used.)

BUT: None of the videos I initially happened to watch mentioned that this only applies to E46 with manual trans. E46 with automatics have not just the electric fan (which sits in front of, and not behind, the radiator, and thus doesn't get removed for this repair), but also a belt driven clutch fan attached to the engine via the water pump pulley. You cannot pull the shroud out without removing the clutch fan. (I believe the distinction is auto versus manual. Doesn't matter really. The point is, if you have a belt driven fan, you need to remove it to get the shroud out.)

The "right" way of removing the clutch fan apparently involves a special tool to prevent the water pump pulley from turning while you use a 32mm open end wrench on the big nut. The backyard mechanic way is a bit cheaper, but you still need a 32mm wrench. Note: I tried a crescent wrench, but its too "thick" to use in the space you have. I've seen others mention that a 1 1/4 inch wrench might work, but I don't know because I was able to find a relatively inexpensive 32mm wrench at Home Depot (a 12 point Husky brand for about $14). It was a little thick, but I was able to get the job done.

Since I didn't have, or want to buy, the special tool to keep the water pump pulley from moving, I used the "whacking it with a rubber mallet" method. Essentially, this means putting the 32mm wrench on the big nut, then whacking the other end with a rubber mallet so that the nut breaks loose before the water pump pulley has a chance to turn with it. It took me a couple whacks. Once the nut broke loose, it came off easily by hand. Note: As you face the engine, the nut loosens by turning to the right (i.e., the opposite of normal). Then you pull out both the fan and the shroud.


2. Getting to the Alternator: Removing the Alternator Serpentine Belt

Not much to add here, except that I have seen some how-to's say to remove both belts (the alternator belt and the lower, air compressor belt?). I only needed to remove the top belt - the one that actually goes on the alternator. Also, when using the Allen Wrench/Hex Key to pull back the tensioner, because of the limited clearance if I used the wrench the normal way, I found it better to put the long end of the wrench in the tensioner, and then put a long socket (i.e., a spark plug socket) over the short end to grip and for leverage. Puts my knuckles a little farther from harm's way.


3. Alternator Removal: Nothing to add. Two wires, then two bolts (for mine).


4. Replacement Alternator: Oval versus Rectangular Connector

Like a lot of others, I went by the book and bought what appeared to be the correct replacement alternator, but when I went to install it I realized the connectors didn't match. I took out a Bosch 120 amp with an oval connector, and came home with a remanufactured 120 amp with a rectangular connector ($210). After consulting the internet, it appeared there were several possible solutions, including: (i) replace the voltage regulator (which is the part on the alternator that contains the connector) on the reman alternator I just bought with a VR that has the oval connector; (ii) create my own adapter connector; and (iii) instead use an alternator not necessarily spec'd for my car, but that will bolt in and work anyways.

(Note: Another option is to locate and buy the "correct" alternator, possibly from a dealership. But as I understand it, the reman alternator I had purchased was really no different than my original one - it was just the voltage regulator on the alternator used the different connector (the one that apparently is more prevalent in these cars). Given how difficult it seemed to find the actual spec'd alternator with the oval connector, and the potential for added cost and the delay, I didn't see this as my first choice).

According to the internet, it seemed that the 120 amp alternator for a 2003 BMW Z4 would work just fine in my car, and used the oval connector. It would have a third mounting hole (instead of just the two I needed), but it would just remain unused and pose no problem. If it's on the internet it has to be true, :) so back to the parts store.

The 120 amp 2003 Z4 alternator was a little more expensive ($227 for a reman) than the 120 amp actually spec'd for my car (but which had the rectangular connector). But in looking through the book, there appeared to be another possibility: There was also a 150 amp alternator spec'd for a 2005 BMW 325i, and this one had the oval connector (it also had the third, unneeded mounting hole). I read on the internet that a higher amp rating wouldn't hurt anything - you just couldn't go lower. So, given that this alternator was a LOT cheaper ($120 for reman), I decided to hope that whoever wrote that knew what they were talking about and bought it.

Note: My alternator does not have the cooling duct that some have.


5. Reinstallation

No real issues with reinstallation. Just remember that when you try to put the clutch fan back on, it screws on to the left (i.e., opposite from normal). It was a little tricky to get the clutch fan started onto the big nut while also holding the fan shroud, but once it got started I just spun the fan blades to screw it on.

The new alternator seems to work fine, and seems to test out okay.


6. Final Notes

Some people mention removing the upper radiator hose. I didn't.
Some mention partially removing the brake fluid reservoir. I didn't.


7. Post Script: Replacing the Battery

Of course, I ended up having to replace the battery the next day (looked like the original battery). The book called for a Type 49 replacement battery - the same as the original spec. Even so, the original BMW battery was a couple of inches shorter. In the bottom of the battery box, however, there was a little square white plastic block that butts up against the rear (negative) end of the original battery. I pulled that out, and the aftermarket Type 49 battery fit in there perfectly.
 

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Discussion Starter · #2 ·
Some links:

How to replace alternator on BMW 325i
http://www.youtube.com/watch?v=Smz7jOZIfpA

BMW E46 Cooling Fan Replacement (helpful pictures)
http://www.pelicanparts.com/BMW/tec...acement/29-WATER-Cooling_Fan_Replacement.htm#

Removing BMW E46 Fan Clutch Nut
http://www.youtube.com/watch?v=VCxYYk8a2rk


Some other threads that had faced or addressed some of these issues:

Rectangular Vs Oval Voltage Regulators
http://forum.e46fanatics.com/showthread.php?t=891908

Alternator Nightmare (Oval vs Rectangular Connector)
http://forum.e46fanatics.com/showthread.php?t=1033895

help with alternator, can't find correct alternator
http://forum.e46fanatics.com/showthread.php?t=696578

BMW replacement tricks/substitution - alternator replacement
http://forum.e46fanatics.com/showthread.php?t=1018870&page=2
 

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I replaced the alternator on a friends 325xiT. I did not want to screw around and decided to go with a NEW alternators. ECS Tuning has brand new 120 Amp alternators without a core charge, which should be the case with a "new" unit.

New Bosch 120 Amp = $231.88
New Valeo 120 Amp = $288.95

Remove the air box and you should be able to find the stick on the upper rear of the alternator and determine if the unit on the care is Bosch or Valeo and if it is a 90 or 120 Amp unit.

Did this and ordered the Valeo, direct swap, proper connector and air duct on the new unit. Did not remove the cooling fan or anything else other than the air box as I recall.

Again decided to go new because of all the horror stories I have heard with parts store rebuilds and the 2-3 replacement until a unit works and the connector issues. Well worth the extra money IMHO.
 

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Discussion Starter · #4 ·
I replaced the alternator on a friends 325xiT. I did not want to screw around and decided to go with a NEW alternators. ECS Tuning has brand new 120 Amp alternators without a core charge, which should be the case with a "new" unit.
Nothing wrong with a preference for new versus rebuilt. Core charge is really only a hassle if you buy by mail order (and thus have to ship them the core), or if you don't have your core with you when you pick up your new one.


New Bosch 120 Amp = $231.88
New Valeo 120 Amp = $288.95
I'm guessing you haven't run into the oval versus rectangular connector issue. :)
Both of those alternators are clearly stated to be Valeo replacements (even the Bosch one). Both of those have the rectangular connector. Neither one will work out of the box because of the connector issue. Indeed, not one of those listed on the ECS page you got those from will work, as all that include a picture have the rectangular connector, and the one that doesn't include a picture is only 90 amps.


Remove the air box and you should be able to find the stick[er] on the upper rear of the alternator and determine if the unit on the care is Bosch or Valeo and if it is a 90 or 120 Amp unit.
Again, this totally misses the problem. If it was just identifying Bosch versus Valeo and the correct amp rating, I doubt there would be threads titled "Alternator Nightmare (Oval vs Rectangular Connector)."


Did not remove the cooling fan or anything else other than the air box as I recall.
It sounds unlikely to me, but I suppose it's possible. Getting to the bolts on the alternator would seem very tight and awkward. And being able to move the tensioner to get the belt off and back on would seem to be very difficult. But okay.

Again decided to go new because of all the horror stories I have heard ... and the connector issues. Well worth the extra money IMHO.
As indicated above, the connector issue has nothing to do with new versus rebuilt.
 

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Dude,

You totally missed my point, yes there may be differences in connectors, I have read about this, but chose not to become an expert on the hows, whys and whens about the round vs rectangular connectors.

I also have read MANY, MANY horror stories of local auto parts store rebuild units. I am also FAR TOO aware how many rebuilders do not know about all the minor differences between slight variations in the models over the years and they only offer the "common" part.

I was just stating what I did, how I approached the situaiton and what I purchased. It may or may not eliminate the connector screw up?

Again, it was not my car, it belongs to the original owner who purchased the car new and has put ever 130k miles on the car and plans on keeping for as long as they can without headaches.

I would not consider swapping a Bosch in for a Valeo. I assumed with a proper model year application guide, purchasing the proper manufacturer part things would work out, and in my case they did.

And you seem to be questioning how I replaced the alternator??

Well I do not recall everything I removed, but I did not remove the fan, I did not have a fan tool handy so I did what I had to do.

Would it have been easier with the fan removed, probably so, was I able to replace the alternator with the fan still on the engine, yes.

So I am sure some will appreciate all your efforts on the round vs. square connectors and in the future if I run into the issue, I will probably look at all the posts, but I am finding all the rebuild junk these days of questionable quality and I am not willing to spend my time or other peoples time changing parts 2-3 times to attempt to save a few $$$ up front, as in the end it will cost a lot more.

Maybe it is buried in the threads, but I assume there is a specific year(s) and model(s) that may have had multiple connector options or some strange model year split? Hopefully I will not run into this and if I do, I will thank all the people that dealt with it before and offered up solutions.
 

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Discussion Starter · #6 ·
Dude,

You totally missed my point...
Actually, I'm pretty sure I got your point(s), but I responded because it seemed pretty clear you had missed the entire purpose of my original post.

1. Go with new as opposed to rebuilt. I responded that that was certainly a valid personal preference. But it has no bearing on or resolves any of the problems I was addressing in the first place.

2. You listed two alternators, a Bosch and a Valeo, intimating that going to the book and getting one of these new will avoid such problems (you said you didn't want to "screw around"). I pointed out that this was simply incorrect.

3. You just went with what the application guide said and didn't have this problem. This will be true for everyone with the rectangular connector, and so of course misses the point of my original post, which was what can you do if you have this problem.

In your follow up response, you seem to continue to link the new versus rebuilt question with getting the correct connector. It continues to be incorrect.

You also say:

yes there may be differences in connectors, I have read about this, but chose not to become an expert on the hows, whys and whens about the round vs rectangular connectors.
But if that is the focus of the original post, how is your post going to be helpful?


I was just stating what I did, how I approached the situaiton and what I purchased. It may or may not eliminate the connector screw up?
Of course, the answer is it doesn't, unless you don't have the issue to begin with. Again, it simply misses the point. The "situation" was not replacing an alternator -- the situation was unexpected issues one might face in replacing an alternator. By your own words, you did not face the situation addressed, so of course it is unlikely your response can prove helpful on the issue.
 

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Actually, I'm pretty sure I got your point(s), but I responded because it seemed pretty clear you had missed the entire purpose of my original post.

1. Go with new as opposed to rebuilt. I responded that that was certainly a valid personal preference. But it has no bearing on or resolves any of the problems I was addressing in the first place.

2. You listed two alternators, a Bosch and a Valeo, intimating that going to the book and getting one of these new will avoid such problems (you said you didn't want to "screw around"). I pointed out that this was simply incorrect.

3. You just went with what the application guide said and didn't have this problem. This will be true for everyone with the rectangular connector, and so of course misses the point of my original post, which was what can you do if you have this problem.

In your follow up response, you seem to continue to link the new versus rebuilt question with getting the correct connector. It continues to be incorrect.

You also say:



But if that is the focus of the original post, how is your post going to be helpful?




Of course, the answer is it doesn't, unless you don't have the issue to begin with. Again, it simply misses the point. The "situation" was not replacing an alternator -- the situation was unexpected issues one might face in replacing an alternator. By your own words, you did not face the situation addressed, so of course it is unlikely your response can prove helpful on the issue.
Seems that the proper answer is here to figure out EXACTLY what BMW did with the different connections, what years, models and option combinations.

This would be far more helpful to the community overall.
 

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The hardest part is actually lining up the alternator on the mount upon reinstallation. Took me at least 30 minutes.
 

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Discussion Starter · #9 ·
Seems that the proper answer is here to figure out EXACTLY what BMW did with the different connections, what years, models and option combinations.
Or, just be aware that there are instances where you might buy the wrong alternator because you followed the book recommendation but you are one of the unfortunate ones with the oval connector.

This would be far more helpful to the community overall.
And here's the crux. I was just trying to benefit the community that faces the problem I posted about. But if the community finds "I didn't have that problem and have no insight on it, but let me comment on new versus rebuilt" more helpful, so be it.

:)
 

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No worries, suggest you read the links in my signature as if you have not addressed any of those issue, you will be doing these sometime soon.

Better to address them in the warmer months than to deal with them in the dead of Winter!

A few more things for to check out in your spare time:

http://forum.e46fanatics.com/showthread.php?t=967204

http://forum.e46fanatics.com/showthread.php?t=1041726&highlight=

Work your way toward the end of this thread as well - http://forum.e46fanatics.com/showthread.php?t=1042870

There are plenty of other things regarding suspension and cooling systems, but will let you search these out yourself.

BMW, The Ultimate Maintenance Machine!
 
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