1991 E34 Electrical Problem

[mikek]

I have a problem with my 1991 525i E34 M50 that is puzzling, at least to me. I have searched the Internet and this forum for a similar situation, but could not find one.

Last night as I was driving home from work, the SRS light on the dash came on. About a kilometer later, one of the other dash warning lights came on and then then I noticed that the headlights were getting dim.

As I braked for a traffic light, the engine started running very rough and the whole car started shaking as the engine surged. When I turned off the lights and heater, the surging stopped, but started again when I turned the lights back on.

When the traffic light turned green, it took me about 20 seconds to crawl through the intersection. Fortunately, there was no traffic and I limped to a place to stop. By the time I coasted to a spot, the engine had died and there was very little electrical power left to illuminate the interior lights.

My first thought was the serpentine belt had broken and I had been running on battery power alone. When I opened the hood, everything appeared as it should. The belt was intact, there were no signs of any fluids leaking, and the alternator was cold to the touch.

After about five minutes of scratching my head, prodding relays, and tugging on cables, I noticed that the interior lights were now bright. I turned the ignition key and the car started fine and ran as if nothing were wrong. Even turning on the headlights and heater did not cause any changes in RPM or cause any warning lamps to illuminate. Since I lived about one kilometer away, I drove home without a problem.

Today, I decided to drive to the next town, which is about 15 kilometers away. As I neared an intersection, the SRS light came on and about 30 seconds later, all of the dash instruments died, followed quickly by the engine. When I turned the key to the run position, the lights and gauges on the dash were dead. When I tried to start the engine, there was nothing.

After about ten minutes, it appeared as if all power was restored, except the car still would not start. When I turned the key to the run position, all of the normal dash lights came on and the gauges were active. When I tried to start the engine, the starter motor would engage, but after one attempt to turn, it would stop. It had the appearance of a dead battery.

I called ADAC and waited for about 15 minutes, all the while making new friends at the busy intersection. On a whim, I tried to start the car and as it did last night, it started without a problem.

About ten minutes later, when I was almost at my destination, the SRS light came on, but I had parked before the total power loss occurred. The car remains where I parked it and my wife picked me up.

If I can rule out demonic possession, what could be causing this problem?

If it helps, here are more particulars about the car.

It has about 295,000 kilometers on the original engine
Automatic transmission (replaced ten years ago)
New thermostat (previous thermostat failed open)
I keep getting the coolant level warning, even though the level is fine.

I appreciate any help!
Mike

[mikek]

Now that I think about it, the first light that comes on is the yellow ABS light on the far right of the instrument cluster, not the SRS.

[mikek]

I found the problem. The brushes on the voltage regulator are worn. One of the brushes was not even making contact with the alternator ring. Off to the dealer tomorrow.

Contrary to what I read, this was NOT an easy task. It might be easier to access some of the hardware from below the car, but I was working on the street and did not have access to a lift.

After fumbling around for an hour trying to take the wiring harness off the alternator, I decided to remove the two mounting bolts and maneuver the alternator around to remove the harness nuts.

[Highline]

because you mention ADAC and km instead of miles.
First of all for the feedback.
There is a very good German forum for the E34 drivers. So if you understand, register there too
http://www.e34.de/frames.php
I am also a member there, very good knowedge in electronics also there.
Shogun E32 Tech Tips: http://twrite.org/shogunnew/topmenu.html

[mikek]

I am stationed in Germany with the US Army. I have been in Darmstadt for a while, but my German is not good enough yet :(

[Highline]

to get cheap parts.
Andre Abenson is quite good with used parts, he lives in Wiesbaden near Frankfurt, also speaks a bit English.
Well known among the E32 and E34 drivers, reliable, cheap.
http://stores.shop.ebay.de/7er-Teile__W0QQ_armrsZ1
the phone and email number is in all the offers there, so just call him or send him an email. He has more than he can list.

Quality parts only, no chep stuff, Cristpger there speaks English
http://www.car-parts24.eu/

Well known shop on the E34 and E32 forum in Germany, most of them drive E34.

Goede http://stores.ebay.de/Autoteile-Gode-Groshandel_BMW-Teile_E34_W0QQcolZ2QQdirZQ2d1QQfsubZ7075941QQftidZ 2QQtZkm
front and rear sus parts, shocks, brakes. If not lised in the auction house, call them. They can supply all for your car.

from Berlin: http://www3.kfzteile24-shop.de/
In Germany to select parts, you always have to select the KBA numbers:
KBA-Nr. (2/3)
see the left side in your link above. Your 1991 525i E34 M50 192 HP 24V
has the
KBA-Nr: 0005-493
note that number down, then inster there and all parts will pop up which fit your car.
I have done that for you now, hopefully the direct link will work
http://www3.kfzteile24-shop.de/index.php?NAV=Select&ktypNr=00241&SKtypNr=00241&kher=00016&zwei=0005&drei=493&fsel=3
and here my translation help

Abgasanlage = exhaust system
Achsaufhängung/Radführung/Räder = sus/steering/wheels
Antennen / Radiozubehör=antenna/radio accesories
Antriebswelle / Antriebswellengelenk / Manschetten = drive shaft/drive shaft joints/rubber seals
Bremsanlage = brakes
Elektrik: Beleuchtung / Anlasser / Lichtmaschine =electrics/lights/starter/generator parts
Filter /filters
Getriebe =gear/transmission
Heizung / Lüftung = heating and airation
Karosserie / Stoßstange / Kotflügel / Spiegel = chassis parts/bumpers/fenders/mirrors
Klimaanlage / climate control/aircon
Komfortsysteme = comfort systems
Kraftstofförderanlage / Tank / Tankverschluß= fuel supply/gas tank/fuel gas flap
Kupplung: Kupplungssatz / Ausrücklager / Kupplungsseil = clucth parts/clutch bearings/clutch bowden cable
Kühlung / Wasserpumpe / Thermostat=engine cooling/water pump/thermostat
Lenkung / Servopumpe / Spurstange / Lenkgetriebe =steering/power steering pump/tie rods and stuff/steering gear
Motor / Motoröl / Dichtungen / Ölwanne / Stößel = engine parts
Scheibenwischer / Wischermotor / Wischerpumpe=wiper+washer system parts
Stoßdämpfer / Federn / Federbeinlager / Domlager = suspension parts such as shocks, springs, shock mounts
Zahnriemen / Keilriemen / Spannrollen / Umlenkrollen = belts/rollers/tensiones etc
Zündungsteile = ignition system parts
German Ebay, fixed to E34 parts:
keep this link:
http://search.ebay.de/BMW-E34_Auto-Motorrad-Teile_W0QQcatrefZC6QQcoactionZcompareQQcoentrypage ZsearchQQcopagenumZ1QQfcclZ1QQfclZ4QQfromZR10QQfso oZ1QQfsopZ1QQftrtZ1QQftrvZ1QQga10244Z10425QQsabfmt sZ1QQsacatZ131090QQsaobfmtsZclassifiedQQsaobfmtsZi nsifShogun E32 Tech Tips: http://twrite.org/shogunnew/topmenu.html

[mikek]

[mikek]