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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E39 (1997 - 2003)

E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #26  
Old 09-19-2010, 06:53 AM
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540iman 540iman is offline
resident, old fart
Location: N.W. Indiana
 
Join Date: Sep 2008
Posts: 1,504
Mein Auto: 2002 540i sport
Come on BB, you aren't posting from memory!!! Good job of explaining how the diode acts and essentially why the tests we do on the speed sensors works. I can't tell you how many times I have used a string of rectifiers to reduce voltage (poor man's voltage regulator). Say you had a 9V wall wort and needed instead a 6V wall wort (bad example as wall worts have terrible regulation). So, you need a 3V drop. 4 diodes in series will reduce voltage 2.8V which is close so you could add 4 diodes in series to the positive side of the wall wort and as long as the diodes are rated for at least the current you will draw, they will drop the voltage beautifully. Some might try a resistor, but the voltage drop will then become a function of the current draw so a given resistor will drop voltage a different amount depending on the current draw (E=I*R) so 2.8 volt drop requires knowledge of whatever the load will be to determine what resistance is needed. Ok Blue, can you explain why when you use a full wave bridge rectifier that it will not drop the input AC voltage, but increase it by a factor of 1.414?? In other words, if you have 10 volts AC and want to turn it into a full wave DC voltage using a bridge rectifier, that the voltage at the output side of the bridge will be 14.14V?? Just testing you!! If you instead use a half-wave set-up, the output will be REDUCED by a factor of .7 or about 7V DC will be produced instead of 14VDC if you use a Full wave bridge. Splain that will ya Blue??!!

My question is: Has anyone found an alternator re-builder who states the ALWAYS replace the regulator and rectifier trio? I have only found, as most have, the guys who say "replaced if necessary" which means if it is turned in as a core with a rectifier trio that is working at that minute, they leave it! It could fail from use/age in 5 minutes! At least if they were to replace you would know you are starting with a motor that has *zero* miles on it. If anyone finds a site that says they always replace the semi-conductors regardless, I would love to know who does this.
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  #27  
Old 09-19-2010, 07:17 AM
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bluebee bluebee is offline
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Location: San Jose, California
 
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Mein Auto: 02 BMW 525i M54 auto 130K
Quote:
Originally Posted by 540iman View Post
Come on BB, you aren't posting from memory!!!
Actually, I was. I used to use the 7805 all the time when I took an electronics class in adult school. I never could understand the 7905 which was a negative voltage regulator. (Still don't understand it to this day.)

Quote:
Ok Blue, can you explain why when you use a full wave bridge rectifier that it will not drop the input AC voltage, but increase it by a factor of 1.414??
Seriously I'm not looking this up. But I do remember "something" somewhere, about 1.414 being the RMS voltage. Am I at least in the right direction?


Quote:
My question is: Has anyone found an alternator re-builder who states the ALWAYS replace the regulator and rectifier trio?
Actually, it would be nice to get a bill of sale that explains which components were replaced with what (which is cn90's whole point). I bought mine from OEMBimmerfest's web site but I wouldn't know what was replaced.

Quote:
If anyone finds a site that says they always replace the semi-conductors regardless, I would love to know who does this.
+1.414
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  #28  
Old 09-19-2010, 10:13 AM
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ketchup ketchup is offline
Wrenchin'
Location: San Diego, CA
 
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Mein Auto: E46 M3
good god does she(?)know her stuff!
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  #29  
Old 09-19-2010, 12:25 PM
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MatWiz MatWiz is offline
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Location: NYC
 
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Quote:
Originally Posted by bluebee View Post
..... and the whole thing is in a wheatstone bridge like configuration (someday they'll name a bridge after me ... ).
Yep. And then I can say to people who argue with me, "Yeah, and I have a Donna Bridge to sell you too."

mw
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  #30  
Old 09-19-2010, 10:21 PM
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ketchup ketchup is offline
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Quote:
Originally Posted by MatWiz View Post
Yep. And then I can say to people who argue with me, "Yeah, and I have a Donna Bridge to sell you too."

mw
"Tanks but no tanks to that bridge..."
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  #31  
Old 09-20-2010, 10:55 AM
cn90 cn90 is offline
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Location: Omaha NE
 
Join Date: Mar 2006
Posts: 12,838
Mein Auto: 1998 528i 5-sp 140K+
From the pro rebuilder:

- When a voltage regulator goes bad, it can damage the diode trio (rectifier). But as a general rule, voltage regulator fails frequently with age.
The rectifier rarely rarely goes bad.

- A major rebuilder for Bosch in Michigan can offer:
a. New Bosch Alternator (no need for core charge because it is new): $400
b. Reman Bosch Alternator: $180 (with core charge) and who knows what parts were replaced.

Some more tids/bits:

1. To look up PNs for Alternator, this is a good website from the UK:
http://wo***********
My 1998 528i Rectifier is "RTF39818" or Bosch PN 1127319712.
http://wo***********/Component.aspx?Ref=RTF39818

2. A good supplier for rebuilders and individuals is IAT USA Inc.:
http://www.iat-usa.com/
IAT USA Inc.
61-32 2nd Avenue
Woodside, NY 11377 USA
Tel : (718) 956-4248 Toll Free: (800) 872-8890
Fax: (718) 956-4310
Email: sales@iat-usa.com

Last edited by cn90; 09-20-2010 at 11:00 AM.
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  #32  
Old 10-11-2010, 07:51 AM
anbu_nee anbu_nee is offline
AK 535xi
Location: Akron, OH
 
Join Date: Aug 2007
Posts: 10
Mein Auto: 2008 535xi Sprt,Prm,cold
new alternator for $550

I just replaced my alternator for $550 and $120 labor. I didn't know rebuilding in an option.
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2008 535xi Sport, Prem, Cold
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  #33  
Old 10-11-2010, 08:04 AM
cn90 cn90 is offline
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Mein Auto: 1998 528i 5-sp 140K+
Quote:
Originally Posted by anbu_nee View Post
I just replaced my alternator for $550 and $120 labor. I didn't know rebuilding in an option.
When did yours fail? 125K, 150K, or 175K miles?
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  #34  
Old 10-11-2010, 08:45 AM
wolfen wolfen is offline
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Location: New Jersey
 
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Posts: 408
Mein Auto: 97 BMW 540i
$400.00 for a new alternator is a good deal considering. At that price as of now, i wouldn't bother with a rebuild. The car needs what it needs and should get new OEM parts. I learned back in the day that saving money on rebuilt Starters, alternators etc is wasted money. You will in fact buy twice or trice.
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  #35  
Old 10-11-2010, 08:50 AM
cn90 cn90 is offline
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Mein Auto: 1998 528i 5-sp 140K+
I disagree,
- Rebuilt alternator and Bosch from reputable rebuilders is as good as new.
- Rebuilding these things YOURSELF is even better if you know what you are doing.
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  #36  
Old 10-11-2010, 09:39 AM
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bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
 
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Mein Auto: 02 BMW 525i M54 auto 130K
Quote:
Originally Posted by cn90 View Post
I disagree,
- Rebuilt alternator and Bosch from reputable rebuilders is as good as new.
- Rebuilding these things YOURSELF is even better if you know what you are doing.
Plus, if you rebuilt it, you're more likely to have ALSO replaced the belts, mechanical tensioners (or hydraulic tensioner pulleys), and idler roller.

The only problem I see with rebuilding is you need to plan ahead!

It would be nice if a single rebuild "kit" were available for the Bosch 120 and whatever other common alternator is used in the E39.
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  #37  
Old 05-29-2014, 08:58 AM
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bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
 
Join Date: Mar 2008
Posts: 21,106
Mein Auto: 02 BMW 525i M54 auto 130K
For the crosslinked record, there is a nice valeo rebuild going on today over here:
> E39 (1997 - 2003) > No power from alternator + no red light battery
Quote:
Originally Posted by LaroxMW View Post
This are pictures with alternator dissambled. It is little oily because i clean with gas
The car is E39 2001 2.2 bezine, 170 horse, M54 motor.

See also:
- Complete DIY for how to test a BMW battery & alternator (1) & how to determine exactly what alternator you have (1) & how to determine the proper replacement alternator brand and amperage [Valeo, Bosch, 90A, 120Amps, or 140 amps] (1) & how to tell from the part number if a replacement alternator is actually rebuilt "by" Bosch (1) & one users' example of total electrical failure (AAA towed away) alternator repair (1) [Read post #66 & post #107 & especially post #146] & a DIY for replacing the E39 I6 alternator (1) (2) (3) (4) (5) or E39 V8 alternator (1) (2) (3) (4) & why you want to clean out the air-cooled alternator air duct & cooling vents (1) (2) (1) (2) & does an ATF leak from power steering hoses onto the alternator cause the bearings to fail (1) & why rebuilding an alternator is preferable to replacing (1) & cn90 DIYs for rebuilding a 1998 air-cooled BMW Bosch alternator (1) (2) or his VW Bosch alternator (1) & cdawg246's quest for materials for a Bosch water cooled alternator rebuild (1) & Aioros' 1999 Valeo Alternator rebuild DIY (1) and his quest for materials (1) & Cn90's explanation of where to get hard-to-get alternator rebuild parts (1) & a DIY for replacing the brushes in an (Audi) Valeo alternator (1) & a Bosch alternator bearing replacement from a 1997 MB S600 (1) & from a Range Rover (1) &, if it's not the alternator, a diagnostic procedure to test for overnight parasitic battery drain (1) & how to find all the fuses (1) & how to choose a good aftermarket battery (1) and a simple battery replacement DIY (1) & where to find the battery explosive charge emergency quick disconnect (1) (2)
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Each repair should invariably add to our knowledge base by the process of inexorable incrementalism.
Your job, in return, is to read the suggested threads, where the best people will always add value to those threads, either by pictures or by descriptions, so the next person with the same problem stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need
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