Hint for correct installation on the large 140A Bosch alternator on the M70, also used on E32 735 etc.
I sent to to someone with an 01/1991 E32 750i a voltage regulator, then he posts the following: Voltage Regulator replacement results in LOWER voltage at OBC! Previously I would get 13.5-13.9 V at the OBC test readout. I decided to replace the voltage regulator with one supplied by Shogun (Hella). Now that I've had chance to drive the car I'm only getting 12.99-13.45V (even at over 1500 rpm) depending whether or not lights and auxiliary cooling fan are on! How can this be? I test fitted the new voltage regulator twice and mounting screws fit properly. I noticed that the black plastic cover would not fit perfectly flush with the new regulator and I assumed that this was because the round black metal cap on the voltage regulator is somewhat higher/thicker? What should I do?, Remove and replace voltage regulator again? I can do that without removing the high pressure lines from the block, (I think). Or should I just replace the entire alternator? (remove radiator, tensioners, alter bolts, etc.). It's going to get cold here again and I need good charging voltage! Photos of old regulator attached. http://www.bimmerboard.com/members/b...r/IMGP0344.JPG http://www.bimmerboard.com/members/b...r/IMGP0346.JPG
Battery voltage as measured at the engine room + and strut tower - terminals is 12.7. While at idle, voltage at these points is 13.5V-13.7V. At the same time OBC test 9 says around 12.9-13.3 fluctuating occasionally as high as 13.5. Also, interior lights PULSING now and not before!
some days later...... Eureka! I found the problem, now I can go and kick myself in the A$$! The attached pictures tell the story. The voltage regulator replacement while in the car is very difficult and you can't see how it goes in. I should have used a mirror. The first photo shows the incorrect installation and the last photo is the correct installation. Note that there are additional screw threads in the mounting surface above the actual voltage regulator. THESE ARE THE SAME SIZE DIAMETER AND THREAD PITCH AND ARE EASILY CONFUSED WHEN YOU CANNOT SEE THE ALIGNMENT OF THE VOLTAGE REGULATOR! I suggest using a mirror, if possible. It is easy to mis-align the voltage regulator resulting in less brush pressure, even though it seems to fit and mounting screws seem to fasten normally. This was the cause of my low charging voltage and with further testing by a local parts store there was "pulsing" of the charge. No wonder the plastic cover did not fit correctly! I though that the replacement voltage regulator was projecting outward because of different dimensions.
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http://www.bimmerboard.com/members/b...r/IMGP0504.JPG