Of Alternators and Fan Clutches

pecsok

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Well, after driving Leela to work for the past several days the alt light has started to illuminate. When I rev the motor the light goes out, so I'm looking at a bad alt! I will switch in a good voltage regulator, just to see if it cures it, but I'm skeptical. I just got a new battery week before last. Any good sources for e9 alternators? Is a 65 amp a good upgrade? What other models can I pillage from?
Also, I'm looking to do a fan clutch conversion. Can I just use the early style (4 bolt) clutch/fan mated to the original h2O pump?

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corsachili

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Any good automotive electrics shop should be able to rebuild your alternator for you. If you go that route you can opt for an internal voltage regulator, but it's not imperative. You can upgrade to higher amperage if you want, but it will cost a little more.

Regarding the fan clutch upgrade, if you're going to do that you might consider going to the later style waterpump which has the single threaded boss for the fan clutch. They're readily available (same pump used on 735s, 535s, even M6s) and eliminating that adaptor will give you some more clearance between the fan blades and the radiator. You should also check to make sure that your engine mounts are very healthy if you do this upgrade as it is possible to have the engine move forward under heavy braking which will cause the fan blades to kiss the radiator (there is but 1/4" or less of clearance in many installations when you do this). In the end, it's a very worthwhile upgrade and will improve the cooling of your precious coupe.
 

pecsok

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Thanks for the reply, TJ

As far as the fan clutch is concerned, wouldn't I be able to just afix an old style, 4-bolt clutch to the existing e9 pulley, or is the bolt pattern different?
I'll be pricing an alternator rebuild locally, as a rebuilt unit is round about 200 or so. Does the e9 have an external voltage regulator? Might as well get a new on of those....
 

corsachili

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If your fan clutch is good then by all means use it, but they rarely are in my experience. The original E9 radiator fan did not have a clutch on it, it's bolted directly to the pulley. The later style fans have more blades and use one of two styles of clutch.

Yes, E9s had external voltage reguators. They're the big square gray box mounted to the side of the relay bracket on the driver's side fender well. I went to an internal voltage regulator which cleans up the wiring a little, but if you're overly concerned with originality you might want to keep yours as is.
 

pecsok

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re

Well I purchased a rebuilt alternator (Bosch # al43x) and swapped it in last night, along with a new voltage regulator. However, the alt light remains lit. Just to make sure I wasn't dealing with a bad battery, I swapped it out as well. Light still lit. I noticed, though, that the new alt had a detail that differed from the old one: The brush holder on the new unit had an exposed 3-prong plug on it, whereas the old unit (Which had a remanufactured label on it, so it isn't the original unit to the car) has a black box on it. Could the PO have converted to an internal voltage regulator? I noticed there were only two connections I needed to make to the alternator: The large poitive wire attatched with a nut to the post, and another smaller gauge wire attatched to the spade connector on the unit. I was confident the unit was grounded through the mounting bolt. Am I correct in assuming the black box is the internal voltage regulator, and can I simply swap it into the new unit? The brushes look pretty worn on it, so I will try to change those as well, unless the whole unit needs replacing.....
Trying to get her ready for the Hernon, VA vintage Bimmer meet Sept 30th!
 
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