Alternator/regulator suddenly not charging?

Stevehose

Stevehose

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Last weekend my car was running great, no red light and I was getting 13.5v when running at the battery. This am I start it up and the red light is on and no charging - 12.5v with engine off and 12v with engine on. Can the alternator go out overnight like this? Could it be the regulator fried? No gradual faint red light like the usual alternator about to fail scenario. Should I test the alternator directly like the manual says or is there a way to test regulator first? Thanks.
 
Sounds like your warranty just ran out...

Only 2 screws to that regulator- pop it out and take a look.
 
That diagnosis method will not catch bad alternator diodes. I think it is a nice first-step, but you can have the light off and still not be charged.
 
Gremlin?

Ok so I go out to do the suggested diagnoses and now the light goes out and I am back to 13.5v charging.....I willl check for loose wires etc. unless this is a symptom of iminent regulator or alternator components? Thanks for your replies.
 
What is this part?

It mounts to the power steering pump and the regulator plugs into the plug with the red/brown/black wires, the body connects to a plug coming up from the engine with several wires in it....
 

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But my original regulator plugs into it (see revised pic) so could this still be a regulator with my regulator??? Always a mystery to be solved here.


MMercury said:
Looks to me like a common aftermarket transistorized voltage regulator. Probably encased in epoxy. Some of them had an adjustment screw. Original equipment Bosch regulators were bigger

hth.
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Stevehose said:
It mounts to the power steering pump and the regulator plugs into the plug with the red/brown/black wires, the body connects to a plug coming up from the engine with several wires in it....
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Sorry, either I responded too quickly and did not look carefully at a larger version of the thumbnail sized picture or your original picture did not have both units in the same frame.

I am baffled. Indeed, looks to me like your stock OEM Bosch voltage regulator is piggybacked to a common aftermarket transistorized voltage regulator. Have no idea why it would be connected unless the Bosch unit is a dummy and/or not functioning. Could it be an unnecessary backup or something vestigial that someone neglected to remove for fear of offending a previous owner?

W01331631095HUC.JPG

Next you are going to add to the mystery by posting a picture of your alternator that is equipped with an internal voltage regulator. lol

W01331635651KAE.JPG

Sorry , I have no idea what purpose is served by having two voltage regulators connected by the same wiring.
 
Early (very) radio suppression. See aftermarket stereo install.

Since last night was cold for us... you probably just have a loose connection. Unfortunately, the diode plate has soldered connections and if one is loose, same effect.
 
Hmmm since you asked, have a look at my alternator...is that black box a built in reg?

MMercury said:

Next you are going to add to the mystery by posting a picture of your alternator that is equipped with an internal voltage regulator. lol
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Makes sense - I have another radio supressor on the distrib too. It was cold here last night, and jiggling the wires connected to the alt seems to trigger the light on/off. I cleaned everything and reconnected and seems to be working for now. Thanks.


61porsche said:
Early (very) radio suppression. See aftermarket stereo install.

Since last night was cold for us... you probably just have a loose connection. Unfortunately, the diode plate has soldered connections and if one is loose, same effect.
Click to expand...
 
Find the alternator numbers and run through OEM. circa 75 was when Bosch got screwy. Usually- original internal has Hella regulator if you can read the end.( white ceramic, with metal disc.)

If you want to be absolutely sure everything is fine- take the alternator and have a load test done.
 
Stevehose said:
Hmmm since you asked, have a look at my alternator...is that black box a built in reg?
Click to expand...

I will defer to 61Porsche's logical suggestion about radio suppression. It is not particularly clear to me why the suppression or filtering device would be placed inline between the regulator and the alternator with a three prong connection. Then again, I have difficulty spelling amps and ohms.

To the best of my limited knowledge, the small black rectangular object depicted in your two pictures - is not a voltage regulator. It serves as a suppression device. (part no "3" below)

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I posted two pictures before. The first was an example of an aftermarket standalone voltage regulator that seemed superficially similar to the device in your picture. I noticed that there are some markings on the mystery unit in your first picture, but can't make them out. A search might provide more info.

My detective skills are not that sharp, but it does not appear that you have an internally regulated alternator. For what its worth, the second picture is an example of an aftermarket voltage regulator and brush assembly that screws into the back of the alternator and thus makes the alternator internally regulated.
http://www.e9-driven.com/Public/Library/BMW-E9-Manual/pages/en/12320010.html#refertoc

hth
 
Unless you are a real stickler for originality, my advice would be to replace both your alternator and regulator with a more modern, internally-regulated alternator. I bought a new unit from bnr parts for about $120. See: http://stores.ebay.com/BNR-PARTS-AL...12236110&_sid=592694387&_trksid=p4634.c0.m322

Call the nice people at bnr (848 442 9082), tell them you have an e9, and they will tell you p/n of the newer alternator that fits a coupe.

The conversion has been discussed here on the forum - basicly just disconnect the wire to the warning light from the 3-terminal connector that plugs into the regulator, and connect it to the 1/4" spade terminal on the new alternator. The heavy power lead connects the same way. Oh, and do disconnect your battery first.
 
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