alternator advice needed

[dieselnutjob]

I am a long, long way from home and today the 806 alternator appears to have packed up.

 

Initially the alternator warning light came on and the AC packed up but only at high revs.

 

I pulled over and put a new alternator belt on because I had one with me and the tools to fit.  I was wondering if maybe the belt was slipping.

 

It didn't make any difference.

 

I think that the AC is a red herring because it seems that if the alternator warning light comes on the car automatically turns off non essential things such as AC and even the interior blower motor.

 

The engine revs that cause the light to come up gradually came down until the light is now on all the time.

 

Also a voltmeter confirms that the battery is not charging.

 

Before I make an emergency alternator purchase, is there anything else that can cause an alternator to stop working?  I mean, is there a relay somewhere that has to energise something before it will work properly or something like that?

 

I would like to do some simply checks before I condemn the alternator, and it's an expensive thing to change if actually it's just a wiring fault or a bad relay or something.

 

The 806 is a 2.0 HDI

[jbz2079]

Because of the way it gradually failed, I think the brushes have worn out and it has gradually stopped charging at all.

When it was not charging at high revs earlier it would be the brushes chattering on the slip rings.

 

If it's fitted with a Bosch alternator it might be possible to fit just a new regulator with new brushes and it should start charging again.

Valio or anything else might mean a new or recon alternator is needed.

 

Check the connections to the alternator first though, just might be a broken wire.

[Pillock]

Broken wire could do that.... the decent voltages at high revs will build up heat at the point of high resistance if the wire is loose or breaking down, get hot, break down a bit more, bit more resistance till it's doing it even at low revs.

[dieselnutjob]

based on what people have said I had another look

there appear to be only two terminals on the alternator so that would make it one to the warning light and load relay, which is clearly working, and the other going to the battery.

With multimeter on ohms range I get 0 ohms from alternator terminal to battery

With multimeter on volts range I get the same voltage at the battery as the alternator terminal, engine running or not.

It seems to be a Valeo

 

As it has done 225,000 miles I suspect that I have just worn it out, which is fair enough.

 

At least I have tools and somewhere to mend it.

[dieselnutjob]

recon alternator is in

wallet is lighter

car is okay

thanks everyone

[dieselnutjob]

if I had been at home I would have done this

 

http://www.youtube.com/watch?v=aVvPzwtxdrM

 

it seems that you can replace the brushes on a Valeo alternator yourself