E34 m5 alternator -urgent!! - The Unofficial BMW M5 Messageboard (m5board.com)

MICKEYDOO81 · 30th June 2009, 01:06

Hello peeps
looking for some urgent help !!
I need a new 1 of the above as mine's has packed in no charge getting held whatsoever

anyone know where i can get 1 of these from for wednesday pm!!
Txt 07946745161 - michael

hellpppppppp

Phlem5 · 30th June 2009, 01:33

Mick, welcome along. I would suggest you get it refurbed as a new unit will cost you circa £600 - dealer only. Maybe David Oli has a used one you could get, try sending him a PM. Only other thing I can think of is to try another non M5 alternator as a temporary fix, not sure if another one will fit but it's your best bet for Wednesday. For refurbing you could try Shandon Electrical in Motherwell.

MICKEYDOO81 · 30th June 2009, 01:35

God.................
Yous guys are something else

problem solved!! Buying 1 tomorrow from dave

absolutley amazing response

davidoli · 30th June 2009, 01:43

Always a pleasure Michael , never a chore ......

DHL collection booked for tomorrow , good luck and welcome to the board !

D

Phlem5 · 30th June 2009, 01:53

Happy Days....nice one David. Might be worth getting a new toothed bracket and nut from the dealer to alay any tensioning gippy when fitting Mick.

IvanDias · 30th June 2009, 11:34

Just to chime in with a bit of info should anyone search this in the future.

Often it is just the Rectifier and not the alternator itself. This is about £70+ from BMW and £9 from GSF Parts. I have had one cheap one fail but hardly a large sample audience.

The 535i alternator can be used as a stopgap. The difference is the casing, the 535i unit has an upwards facing air vent with no piping, the M5 unit faces down and plastic pipes link to it to take in cool air from the bumper area.

Early and low spec M5's came with a 110amp alternator, the juicy M5's had a 140amp unit. If your car requires a 140amp unit then obviously you'll need to chose a matching 535i one as they came in 90, 115 and 140amp versions.

Note 1- I have never seen the 140amp variant of the 535i unit so do not know if it is also uncooled.

Note 2 - Back to the M5, I melted a rectifier after 6 months driving about with a 140amp alternator in my car replacing the 110amp unit when I found the cooling piping had fallen off on the road sometime!

Note 3 - After the alternator failed I found that it was killing Rectifiers as the slip ring was ovalised. This is something that an alternator rebuild will remedy. If anyone knows who offers a rebuild service (I'm UK but all suggestions welcome for other readers) for a good price I would like to know as my spare alternator needs this doing.

Kind Regards

Ivan

e34guy · 1st July 2009, 09:11

Quote:

Originally Posted by IvanDias

If anyone knows who offers a rebuild service (I'm UK but all suggestions welcome for other readers) for a good price I would like to know as my spare alternator needs this doing.

Kind Regards

Ivan

I don't know specifically about M5 alternators but I have used these guys for refurbing bike bits , and they have had good reviews from others:
reading alternator auto electrics - Google Maps

Steve

farrell · 9th July 2009, 11:27

Gents
The Bosch Alternator as fitted to M5 is completely serviceable.
As Ivan says, most require slip rings as these knock at least one tooth off
the brush cotacts.

Even with a diode failed, most of these units will crank 120 Amps on a
Alternator dyno, many see 140 Amp plus.

The replacement cost for a new unit is mostly down to a bespoke end casting, not the internal
serviceable items which are reasonable cost.

Regulators, slip rings & brushes are the main failure items.
The stator & individual diode within the pack can fail.
This is a rare occurance but is generally a driven failure not helped by a blocked intake cooling duct*
RealOEM.com BMW E34 M5 3.8 ALTERNATOR PARTS 140A

*Preventative maintenance :
I would advise keeping the cooling duct from the bumper bar to the alternator clear.
RealOEM.com BMW E34 M5 3.8 ALTERNATOR COOLING
If you remove the vertical plastic duct from the inlet volute on the back of the
alternator, you may also find leaves & debris build up.

The duct itself becomes brittle & fractures with age reducing cooling efficiency.
A replacement is £25 or so for the complete intake duct asy.
It's available Germany only so will take 5-7 working days on a VOR.
Stock order will take 12-15 working days as they tape the part to the
back of a snail.

Failing this, I can completely rebuild & test them for you if required.

Cheers
Farrell

beemerchris · 9th July 2009, 19:31

Quote:

Originally Posted by farrell

Gents
The Bosch Alternator as fitted to M5 is completely serviceable.
As Ivan says, most require slip rings as these knock at least one tooth off
the brush cotacts.

Even with a diode failed, most of these units will crank 120 Amps on a
Alternator dyno, many see 140 Amp plus.

The replacement cost for a new unit is mostly down to a bespoke end casting, not the internal
serviceable items which are reasonable cost.

Regulators, slip rings & brushes are the main failure items.
The stator & individual diode within the pack can fail.
This is a rare occurance but is generally a driven failure not helped by a blocked intake cooling duct*
RealOEM.com BMW E34 M5 3.8 ALTERNATOR PARTS 140A

*Preventative maintenance :
I would advise keeping the cooling duct from the bumper bar to the alternator clear.
RealOEM.com BMW E34 M5 3.8 ALTERNATOR COOLING
If you remove the vertical plastic duct from the inlet volute on the back of the
alternator, you may also find leaves & debris build up.

The duct itself becomes brittle & fractures with age reducing cooling efficiency.
A replacement is £25 or so for the complete intake duct asy.
It's available Germany only so will take 5-7 working days on a VOR.
Stock order will take 12-15 working days as they tape the part to the
back of a snail.

Failing this, I can completely rebuild & test them for you if required.

Cheers
Farrell

Nice one Fatz

will keep that in mind always good to know that this can be done rather then buying another unknown item that might fail in the future. The ducting on my 540 was brittle as well and I'm glad now I changed it completly.

chris

davidoli · 9th July 2009, 22:09

Just for the record , how much would this rebuild service cost ?

Are the alternator cooling ducts still available from BMW , as I have seen many cars without them ?

Was Fatz a freudian slip ?

D