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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 12-31-2013, 11:34 PM
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bin01123 bin01123 is offline
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Location: Atlanta, GA
 
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Mein Auto: 2001 540i 6 Speed
Thanks. I'm all over it, plus it has a lifetime warranty.
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  #27  
Old 01-01-2014, 02:01 AM
yousaveone yousaveone is offline
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Mein Auto: Hopefully the 850i
Quote:
Originally Posted by avu3 View Post
The 540 has a water cooled alternator, there is no ducting to clog up.

Doru, thank you for the suggestions. I'll lift the carpet and have a look under there. I've never spilled anything, but who knows what happened under prior owners.

Scott
Pre Vanos 540s have an aircooled alternator.
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  #28  
Old 01-24-2014, 11:45 PM
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bin01123 bin01123 is offline
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Originally Posted by bin01123 View Post
How are you doing with the MPA alternator? I found one for 163 online without a core exchange.
Installed the MPA alternator today and it worked for ten minutes then failed. It continued to work then fail. Had high hopes for this brand.
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  #29  
Old 01-25-2014, 07:43 AM
skborders skborders is offline
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Mein Auto: 2000 528i
The first thing you should do when you have a Alternator or Starter problem is to have the battery tested.

Anytime you replace an alternator you should do a voltage drop test on the Charging circuit. The single biggest cause of repeat failures of alternators is voltage drop. (I work for a manufacturer) The easiest way is to check the voltage at the alternator and then the battery. Do so with the lights on and the engine at 1200-1500 RPM. The difference should be no more than .5 Volts. If it is higher, check each side of the circuit.
Positive side: red lead at the output post of the Alternator and black lead on the positive post of the battery. Record the voltage (it should be low)
Negative side: Black lead on the case and red lead on the Battery negative post. again record the voltage.
Concentrate on the side that is the highest voltage drop by checking all connections and cables. You can test each one with the volt meter by placing the leads (same operating conditions as above) on each side of a connection (for Example where the Ground cable attaches to the block put one lead on the cable terminal and one on the block near by) or at each end of a cable. Each connection should be .01V or less. Cables will depend on length.

Oh and if the system has a Field wire (a separate wire to provide voltage to the field windings) going to the regulator connection check the voltage on that wire under the same conditions, it should be within a .5V of the system voltage. If it is not the system will overwork itself because it cannot build a sufficient magnetic field around the Rotor.

Same goes for a Starter, measure the voltage at the battery and the starter while cranking. It should not be more than .5V different. If it is, do a voltage drop on both sides of the circuit using the methods cited above only between the starter positive post/case and battery during cranking.

Do not forget, the ground side is just as important as the Positive side as the current has to follow the complete path from one side of the battery (or alternator when charging) to the other. (Actually the current path is negative to positive but the automotive world favors conventional flow)

Tip: Never place a washer between two cables on the same post nor between the cable and the contact point i.e. Battery + post of a starter or alternator or cable end and engine block etc.. Most washers are zinc and will carry current initially but will build resistance quickly.

Last edited by skborders; 01-25-2014 at 07:49 AM. Reason: Added content
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  #30  
Old 01-26-2014, 06:23 PM
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bin01123 bin01123 is offline
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Location: Atlanta, GA
 
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I needed a new battery as well so I put a new alternator and a new battery. I plan on a long road trip and I call myself being proactive. I got a new battery (mine was on its way out) and a new alternator because my car is at 120K miles so I didn't want the alternator failing on me on the road. To update this story, I tried an MPA alternator. It ran for less then 10 minutes then failed. I just tried a Pep Boys Alternator today. It ran 15 minutes then failed. Do I really need to get a Bosh unit at this point? Me trying to be proactive has down a car for the past few days now.

Got the Bosch unit today and it works without an issue.

Last edited by bin01123; 02-04-2014 at 05:08 PM.
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  #31  
Old 01-27-2014, 10:56 AM
skborders skborders is offline
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Location: Atlanta, GA
 
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Mein Auto: 2000 528i
This is why I don't recommend changing things like alternators at a specific mileage. (if it is not broke don't fix it) You have just as much chance of a failure of a reman unit than your original.

Anyway, have you had the ones you removed, tested after they failed? As I mentioned above, high resistance (Voltage Drop) in the circuit is the leading cause of repeat and early failures. That said, if you have a choice between an aftermarket reman and an OE reman, you should always go with the OE rebuilder. They have the Parts available without having to construct a replacement that does not copy the original.
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