High output alternator option for Z3 M's with S54

[CMM3]

With the addition of fans for oil & engine cooling along with an electric power steering pump my alternator was repeatedly failing. With an estimated current draw of around 130 amps it appears that the stock 120 amp alternator was overloaded. I searched the forums and there was some mention of a 140a upgrade that required the connector to be changed.

Working with a great shop locally called Chelmsford Auto Electric located in MA. they where able to find me a brand new BMW OEM Valeo alternator that outputs 160a @3k rpm's, 170a @3.5K rpm's and 180a @ 5k. They were able to cross to the alternator using the voltage regulator part number and told me it was from a 2005 X5.

I tried to find it on Real OEM and could not. But the one they sold me fits perfectly and has the same square plug on the regulator. The only thing that needed to be swapped over was the plastic cover on the back which took about 10 seconds to do with just 2 screws holding it in.

I now see a solid 13.8 to 14.2 volts at the battery with the engine running and all the fans and power steering on, problem solved.

I don't have a BMW part number but if should anyone be looking for to upgrade their alternator you can give this shop a call at 978-649-4448. Ask for Brian and tell him Dan with the BMW Z3 sent you. The part number for this alternator on my invoice is 88004004J and it cost $339 which is a great price.

There may be a core charge but I'm not sure as they took back the 120a output stock version that I bought from them early that failed.

[BimmerBreaker]

Must be an M54 alternator I imagine, since the V8 of that year was water cooled and of a totally different design

[CMM3]

Must be an M54 alternator I imagine, since the V8 of that year was water cooled and of a totally different design

The only one I could find was a Remanufactured unit for the M54, at 140A BMW part number 12317551253 that looks the same. Could be that BMW rates the outputs at idle which might make sense. In any case this one sells for $500 from FCP, with a $50 core charge. Seems like there is a Bosch version that can be found at lower prices.

[///Maniac]

Not that it would be a direct fit, Chris, but my original Alternator for my S50B32 Euro was a 140A. Might be worth looking into - Jonathan

[Randy Forbes]

Must be an M54 alternator I imagine, since the V8 of that year was water cooled and of a totally different design

Really!?!?

We had an '05 4.4 iS for three (3) years, but never having to need to work on it, I never paid any attention to the alternator (I just thought it was cool to see the timing chains through the oil-fill hole!

Thanks Dan, for sharing this info! I doubt I'd ever need it for my own cars, although my coupe runs a coolant pump full-time (whenever the key is switched on) for the air to water intercooler, with plans__someday__to enlarge its capacity.

[rf900rkw]

Yep, that era V8 had the alternator built into the timing chain cover.

[CMM3]

Really!?!?

Thanks Dan, for sharing this info! I doubt I'd ever need it for my own cars, although my coupe runs a coolant pump full-time (whenever the key is switched on) for the air to water intercooler, with plans__someday__to enlarge its capacity.

My pleasure, the shop owner told me that a good rule of thumb is that an alternator should run never need to supply more than 80% of its output. i.e. a load of 80a would be the max for a 100a alternator. I found this amperage load calculator which was helpful.
http://www.qualitypowerauto.com/page...Calculator.php

[MC28REPSOL]

also a good alternator shop can rewire your alternator to put out more. just another option.