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

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

Dear Hugh,

Thank you for your kind reply. I appreciate you taking the time to share your thoughts and experience. I did a poor job of explaining my problem. Please view the exploded view of alternator from realoem.com below:

If you enter the final 7 digits of your VIN number upon entry to the website, you are directed to parts of your car!

I can not remove part #3 to access part #2. BMW , at least in the 5 series, has opted for puting the alternator brushes in the voltage regulator. I think this is clever.

The view above shows one single fastener to hold the cover on. I have removed two and am convinced there is a third fastener, low and a bit to the outboard side. I have decided to get physical with the plastic cover and to break it if necessary. I feel I can then repair it with epoxy.

Best Wishes, Mark

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I no longer need help. With a mechanics mirror and a flashlight, I was able to see the philips head on the third fastener. Mark

Repairing plastic, if it is based on Acrylic (Perspex or Plexiglas or polystyrene (usually polystyrene) is best done with the cement used in plastic model car/airplane type kits. If you go to a model shop or a good hobby shop and get some "dichloramethane".

This comes as a water thin liquid for use on polystyrene based plastics such as those found in cars and window frames etc. and as a gel used with plastic models and other hard plastics such as Acrylic or Perspex/Plexiglas. The gel formula is to make sure the dichloramethane stays in place long enough to melt into the plastic and form a WELD.

Some plastics react quicker than others but both need about 24 hours or more to gain full strength.

I know as my wife is forever breaking those little white plastic hinge pivots off our freezer and also the thin plastic sill in out porch - soon I'll have the whole freezer and porch held together with dichloramethane.

There normally is a set of lock holes - you put a paperclip through them and they hold the brushes back. The paperclip is removed as the brushes and regulator are installed.

What commutator? Alternators use slip rings. The commutators went out around 1959 when generators became commonly used. The diodes do the rectifying - which is why it's called an "alternator".

That's true - most anyplace that has a Bosch sign out front.

Or simply go to an Autozone, Pepboys, whatever in the US and pay $170 for a rebuilt one.

Not so I've seen some with commutator type slip ring contacts - early Lucas spring to mind.

But with those that maybe cheaper than Bosch you can only take them back to the shop you bought from whereas Bosch have a national dealership and any branch will swap out a faulty unit FOC if you have the necessary paperwork in the car and it's within warranty period.

It's a bind having to pay for a new unit and then take the faulty one back fro another - you won't get the cash back.

That still describes a generator - where the commutator does the rectification. An alternator has stator coils that put out alternating current, which is then rectified by the diodes. The rotor only needs to be turned on/off for regulation - the varying magnetic field in the rotor determines the output of the alternator.

There are many more Autozone, Pepboys stores in the US than there are Bosch service facilities. And they also warranty the products - usually with a "lifetime replacement" warranty.

Don't have any idea what you mean by the above..

The commutator does not do the rectification - well it might slightly but the rectification was done in the control - voltage regulator box linked to the battery. Rather hit and miss affair at the time but it worked for about 50 years!!!!!!!!!

That's nice because it never used to happen here. Buy from Fred take it back to Fred.

We always used to fit BL engines and gearboxes to BL cars - Ok cost a bit more but we never had a warranty problem - if it came back to us we just sent the car to a BL dealer. If the customer was in Scotland he took it to a BL dealer.

Usually Fred - the independent will just give you a replacement for the faulty unit. If you had to buy one as a distress purchase you would end up with 2.