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Discussion Starter · #1 ·
After months of not breaking down, something has at last gone wrong with the 3.8.

Started on the button this morning after being left for a week, felt lovely on the way to work and then it ran out of electricity on the A21.

The RAC man said that the alternator has packed up. Anyone got a spare kicking around, or knows where to get a cheap replacement?

BMW want about £500 plus which is a bit of an ask.


· Registered
1,232 Posts
You might want to contact Infinicar (board member) as he has broken a couple of cars and may have one spare.

Also might be worth asking Wane Ramsay as he stripped his car a while back and was selling the parts off, don't know what he has left but worth a PM.


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1,602 Posts
If you want a new one GSF may be able to help, you can get them reconditioned too I believe, or its off to the scrap heap to see if they have any knocking around.

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2,556 Posts
I only have a few minutes to type, but a search will help you out.

My Alternator Experiences 101.

1. Often, it's not the alternator, it's the £10 Voltage Regulator which has failed.

2. If doing this yourself, you can't check the alternator out without refitting, so if it is not the regulator, you have to take the alternator back out again!

3. BMW want £500 crazy money for a new one, so getting yours refurbed is the best bet if it turns out the unit is faulty.

4. Wane Ramsey sold his to me, sorry!

5. There are two versions, the 110 Amp often used in the 3.6 and the 140Amp version used in both cars. I've not yet seen a 110 Amp in a standard 3.8, they seem to be commonly 140 Amp. Obviously if your car has options fitted than required a 140 Amp, I suggest you replace it with that.

6. The 535i Alternator is exactly the same as the 110 Amp version, only the ventilation is up instead of down and it costs iro £90 from GSF. People have fitted this instead of the 110/140 and not cooled it at all to no issues in the past, but I cannot personally comment on longevity if the car originally had or needed a 140 Amp unit.

7. Ever since I put the 140 Amp unit into my 3.6 which had a 110 Amp unit originally, the car starts with the Battery and ABS light staying on until the throttle touched. Starting the with the throttle and key rather than key alone cures this. This had to be explained slowly to the MOT people in order for them not to fail it on ABS light. I have no ideal why this happens, but suspect damage to the electrical system when the regulator failed on Wane's 140 Amp unit 2 weeks after I installed it and the unit was pumping 17+ volts into the car's wiring loom. I will be having the 110 Amp finally looked at in the near future. If it is rebuilt I will swap them back over and finally get an answer whether 140/110 transplant is good on a 3.6 or not.

8. Alternator removal technique is battery disconnected, then fan shroud and then fan out, alternator cooling piping off, then your choice of airbox out or top hoses off (airbox method prob best) for access. Loosen and remove alternator tensioner, then slip off belt. Undo the bolts and then the very tricky lower bolt. Small hands and don't get angry. Remove alternator cable covers from rear, it's brittle and often breaks, then undo cables, freeing alternator for removal.

9. Regulator alone can be changed without removing airbox or coolant hoses if taking a gamble and replacing that only. Technique is battery disconnected, then fan shroud and then fan out. Loosen and remove alternator tensioner, then slip off belt. Undo the bolts and then the very tricky lower bolt. Small hands and don't get angry. Alternator is now free to move about but trapped around it's space in the engine bay. Tilt it and removed alternator cable cover from rear, it's brittle and often breaks, then undo cables. Once released, with patience and swearing, you can undo the regulator and remove it with the alternator still trapped in the engine bay. Once replaced with more swearing, reassemble and try out.

10. I do not have the correct tools to tension the alternator before doing up that tensioner bolt, and have no idea how that toothed wheelbolt does it either! The cowboy method if alone is to jam a sturdy flatblade screwdriver inbetween the alternator and the engine block. Applying pressure brings the alternator up and tensions it. The flatbades handle, (not sharp end) can be moved and will grip the radiator without damaging it. This leaves you with the alternator tensioned and both hands free. The tension for the alternator belt can be judged by wobbling the other belts and adjusting the alternators belt to match. With the screwdriver holding it suitably tight, you can do up the funny toothed bolt correctly. Release 'driver and check tension against other belts. Job done, but best to avoid looking Farrell in the eye for a while.

11. The flip-off cover on the back or the alternator that protects the cables is a bugger and often breaks off after all these years. Also, careful when doing up the cables at the back of the alternator with a socket set, as it is easy for the cables to spin as tightened and crack the plastic around them. Covers are not available as spares from BMW, so if this happens, don't drive through enormous puddles if like so many E34's, yours is missing the oil-catcher tray.


Get the alternator taken out, buy a new Voltage Regulator from BMW and then take both parts to a proper alternator rebuild place. They will clean it and check full functionality, rewinding the coils if required and making it as good as new. Prices I have heard on forums have said about £50-£60 plus the regulator £10 you already bought. This will last years.

You may find this better value than installing second hand units, although you may be off the road for a few days waiting for the rebuild.


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