Re: 2001 530i 5-spd 91,00 miles. How to remove cover from back of Bosch alternator

On Sat, 26 Apr 2008 10:39:55 -0400, mark barron <mbarron@[EMAIL PROTECTED]
>
wrote:

>I want to remove the voltage regulator to check the brushes.
>I hope someone can help me with the removal of the cover on
>the back cover of the alternator on my 2001 e39 530i. The connector
>to the back of the alternator is retangular with two to three
>locations wired. Based on shape of the connector I have been told
>that the alternator is Bosch. Based on this retangular shape and
>"experience" the BMW parts guy told me it is a 120 amp Bosch.
>The car is a few miles away and I lack reading glasses to
>read writing at back of alternator.
>I removed the nuts at the red positive battery cable and the nut
>under the rubber cover(with fins or ridges) . This allows me
>to swing the top portion or the alternator back cover away from
>the body say 1/2". There appears to be a third fastener near the
>bottom of the back cover. There is a tapering concavity at this
>position. Can anyone tell me how to remove this fastener. The
>concavity is - based on finger feel, perhaps large enough to allow
>entrance of say an 8mm socket. I don't need to know the size of
>the bit, but it would help me a lot it you could tell me the
>type of head I am dealing with, torx, hex, slot etc.
>Many thanks. I can't see a thing. even with an angled mirror.
>Mark

Looking at the exploded views on the parts list it appears that the case
is
bolted together with through bolts. These hold the front and rear casing
together as do all other makes. The regulator is held by (apparently) 2
bolts or
nuts and it appears that it could also carry the brushes but I don't think
so.

I would suggest that if you have already removed the cooling ducting and
the
alternator from the vehicle you clamp it in a vice and undo the 3 through
bolts
and gently tap the end cover off the rotor bearing spigot.

It will become clearer then how the brushes are fitted - usually by long
springs
or small coiled levers on the top of the carrier.

The trick in keeping them inside the slide prior to refitting the rear
case can
be difficult.

In the past we used to twist the coiled lever springs to sit on the edge
of the
brush carrier and when in place poke them into place with a bit of rod or
long
thin screwdriver.

When you have the cover off get a fine hacksaw blade and clean out the
commutator segment spacers - these get filled by carbon dust from the
brushes
and eventually will conduct between the segments and cause an internal
short
circuit. Make sure the commutator surfaces are flat and clean - a piece of
emery
paper is Ok for this unless you can remove the pulley and take out the
rotor and
machine the thing in a lathe.

If going to this trouble it might be better to get a re-built unit from an
auto
electrician - that is if you are sure the alternator is faulty - he can
check
this for you while you wait and watch.

Hugh
-- 

Sir Hugh of Bognor

The difference between men and boys is the price of their toys.
 
Intelligence is not knowing the answer but knowing where and how to find
it!

Hugh Gundersen
hsg@[EMAIL PROTECTED]
 Regis, W.Sussex, England, UK