Electrical: Alternator brushes

[morsing]

Hi,

My charging light started glowing faintly, mostly at the beginning of journeys, but the voltage meter seemed ok. Ordered new brushes to make sure I had some and removed the voltage regulator. The Haynes manual says 5mm needed, but mine are equal length and have 8mm left?!

When I ordered the brushes, it did appear that alternators can have either 28 or 32mm slip-rings, could it be a matter of the wrong voltage regulator for the alternator? I believe I changed it at some point.

I started the car up, with a voltmeter and an amp-clamp on the charge cable to the battery, and at first seemed absolutely fine (50+A at 800rpm!). But then it occasionally started dropping to less than 1A charging, although the charge light didn't come on. The alternator terminal was at 11.2V.

I tapped the voltage regulator with a hammer and it briefly started charging again, but then dropped right down. A bit after that, it started charging again.

Should I just fit the new brushes, or is there something else going on here?

Thanks,
Henrik

P.S. I cannot trace the warning lamp cable once it comes out on the other side of the engine. Where does it go?

[Clan]

Originally Posted by morsing

Hi,

My charging light started glowing faintly, mostly at the beginning of journeys, but the voltage meter seemed ok. Ordered new brushes to make sure I had some and removed the voltage regulator. The Haynes manual says 5mm needed, but mine are equal length and have 8mm left?!

When I ordered the brushes, it did appear that alternators can have either 28 or 32mm slip-rings, could it be a matter of the wrong voltage regulator for the alternator? I believe I changed it at some point.

I started the car up, with a voltmeter and an amp-clamp on the charge cable to the battery, and at first seemed absolutely fine (50+A at 800rpm!). But then it occasionally started dropping to less than 1A charging, although the charge light didn't come on. The alternator terminal was at 11.2V.

I tapped the voltage regulator with a hammer and it briefly started charging again, but then dropped right down. A bit after that, it started charging again.

Should I just fit the new brushes, or is there something else going on here?

Thanks,
Henrik

P.S. I cannot trace the warning lamp cable once it comes out on the other side of the engine. Where does it go?

you need the same make of regulator/brush set as the Alternator,

The warning light wire goes directly to the bulb in the dash , the other side of the bulb goes to an ignition live point, possibly direct to the fuse box.

[morsing]

Originally Posted by Clan

you need the same make of regulator/brush set as the Alternator,

Ok, they're both Bosch, so with 8mm left, the brushes are not the problem, right?

Originally Posted by Clan

The warning light wire goes directly to the bulb in the dash , the other side of the bulb goes to an ignition live point, possibly direct to the fuse box.

Thanks, I know where it goes inside the car, I just don't know how it gets there

[Clifford Pope]

Originally Posted by morsing

Thanks, I know where it goes inside the car, I just don't know how it gets there

If you are worried there may be a fault in the wire itself, you could just run another one temporarily and see if it makes any difference?

[Clan]

Originally Posted by morsing

Ok, they're both Bosch, so with 8mm left, the brushes are not the problem, right?



Thanks, I know where it goes inside the car, I just don't know how it gets there

if the brushes are faulty or worn you generally get sparks where the brushes run on the slip rings hence not clean and shiny. 8mm sticking out seems a little short to me.

[morsing]

Originally Posted by Clan

if the brushes are faulty or worn you generally get sparks where the brushes run on the slip rings hence not clean and shiny. 8mm sticking out seems a little short to me.

They look like new. Don't think the new ones I bought are much longer. Haynes says 0.5mm, judging by the imperial measurement, they mean 5mm.

Odd thing is still that the dashboard volt meter reads ok.

[morsing]

Originally Posted by Clifford Pope

If you are worried there may be a fault in the wire itself, you could just run another one temporarily and see if it makes any difference?

That sounds very involved. Managed to track it from the Haynes diagram:

[morsing]

'morning,

Realised yesterday, looking at this, that the rust-proofing shop didn't put the engine under-tray back on! I have been driving around in the rain without it, and this problem, from memory, started after driving in the rain.

Could that be related? (No, the belts are not slipping)

Thanks,
Henrik

[morsing]

Think I fixed it. When I got the car back from the rust proofing place, where they forgot to fit the engine under tray, I replaced the (already) dead battery but forgot to attach the ground wire again.

So the only ground for the charging light (and everything else) was back through the knackered engine ground strap (which I also really need to replace).

I have now replaced both eye-connectors on the battery ground wire, they had both seen better days anyway (!), and re-connected it, and the problem seems to have gone away.

Thanks
Henrik