330Ci - Looks like my alternator has failed

[mwy1964]

Help needed to double check my diagnosis...

Last night while my wife was using the car the battery warning light came on followed shortly by the emmissions warning light. This morning I have checked the voltage at the + post under the bonnet with the engine running and am seeing only 11.7v which would point clearly at the alternator being screwed.

My question is:- Is the + post under the bonnet a good enough place to check the voltage and what voltage should I be seeing. I would expect 13.5 - 14v

Thanks in advance

Mark

[mwy1964]

Good question... Just been out and checked, in the rain, and it looks OK.. I will check properly later once it stops. Also used it as an opportunity to check ease of changing and it looks like it needs the airbox removing to gain access...

Any tips or advice on its change gratefully recieved...

Mark

[Vee]

mwy1964 said:

Good question... Just been out and checked, in the rain, and it looks OK.. I will check properly later once it stops. Also used it as an opportunity to check ease of changing and it looks like it needs the airbox removing to gain access...

Any tips or advice on its change gratefully recieved...

Mark

Changing the alternator is very easy - even I've managed it without any trouble.
Just have a rubber mallet handy to put the new one into place.
If your car is an auto you need a special spanner to remove the radiator fan coupling - not very expensive.

[mwy1964]

Is it a BMW special tool or something you can pick up off the shelf... Looks like its a job for tomorrow afternoon.. Had plenty of practice with hammers of all sizes of recent restoring an old Land Rover...

Ta

Mark

Edited by mwy1964 on Tuesday 30th September 13:41

[Vee]

Off the shelf in Halfords I believe.
I think its called a viscous coupling spanner. Basically its a large, flat thing.

Get hold of new belts and change these while your at it.
You need to make sure its the alternator and not the belt slipping first.

[Shropshiremike]

Vee said:

Off the shelf in Halfords I believe.
I think its called a viscous coupling spanner. Basically its a large, flat thing.

.

There's one made by Laser tools avail in Halfords for about £7

[mwy1964]

Thanks for the advice so far... So of those of you have done the job is there a chance of a quick summary of what needs doing...

To me it looks like Airbox out to gain access and then start removing, a bit lost to why the spanner is needed.. It looks like the alternator pulley sits on top of the belt acting as a tensioner.. Excuse me, perhaps, being a bit thick here I am looking in between rain showers...

Mark...

[Vee]

When I did mine . .
Disconnect battery
Fan out (you need the spanner for an auto)
Remove belts - tensioners turn the opposite way I think
Take of alternator
Put new one on
Replace belts
Fan back in

There are detailed instructions on e46 fanatics

[mwy1964]

Great thanks for the pointers...

Mark..

[mwy1964]

Its out.... 1 hour, most of the time spent playing around with the combination of fasteners BMW use to hold the simplest of things in place.. And then trying to find them in the garage... Did not need any special tool to take the fan off. The fan shroud would not clear the fan blades so pushed it back and removed the three allen bolts that hold the fan onto the hub.

I see why you need a hammer, even with all the bolts removed it was tight on the mounts.. The only other thing that caught me out was the belt tensioner that went to its limit on removing the top alternator bolt and idler pulley.. Took some force to push back and put a small bolt into the tensioner locking holes.. Far easier if I had done it before removing top bolt...

So now looking for recommendations on best place to buy 120A Bosch alternator - GSF, Europarts or An-other... BMW want over 300 quid...

Thanks in advance

Mark

[phelix]

Have a look at the brushes; are they just worn down? Or get an auto elec shop to check it out and replace the duff bits.