Alternator Failure

[Citroënbender]

Not an Alfa or Ford… I’m curious as to what those with shop experience, think begat this problem. Mismatched diode banks, FOD, oxide tracks, insulator cracking…

It’s not a trick question, this is an older rebuild of mine (c. 2009) and has only done about 60K since then - it lives outdoors, though. I’d rather fix it right, removing the unit is a fair hassle and so is reinstallation.

Naturally, being a Japanese alternator on a French car, it looks as though spare parts will have to come from the Ukraine.

[Franco Cozzo]

Stator windings on the right hand side are showing high resistance connections and some contamination/oily residue around the brush box, what car is this from and where is the alternator on these things?

[Citroënbender]

It’s a Pug 405, the A3T03298B alternator is up high at the front and tucked under the inlet manifold. No aftermarket loads on the system except (maybe) the massive new 720CCA battery? Oiliness is probably general blowby/misting/creep from engine wear and loss of crankcase vacuum, plus ageing seals.

I see your point about the RH diode bank looking stressed, there further seems to be something broken inside it. Does it matter if these trio pairs are mismatched in current capacity? The RH (original) is nominally 25A rated diodes while the LH replacement is 35A.

[slowsnake]

Why not just buy a new no name brand CB?.....my el cheapo delivered to your door for lesser dollero works fine!
You seem to have a lot of projects on the boil all at once, why not just replace and not rebuild?

[Citroënbender]

I’ve arrived at a possible scheme of failure.

Three rectifier diodes have been replaced in the distant past. The original block type were stripped out and pressed diodes fitted, using a bit of solder to secure them against coming loose.

The centre replaced diode looks to have shorted. Progressively this has heated up the rectifier pack, melting out solder used to secure the diodes. Some has fallen into a low point where it bridged the rectifier buses. This furthered the short, heating the bridging contact to the other rectifier half-assembly and melting off its solder.

[slowsnake]

That's not a failure CB, it's called a catastrophe!......
I'd say "your goose is cooked"

[aussiblue]

What solder was used? Something in the back of my mind is saying that rather than standard resin cored solder very high melting point solder using separate resin paste is meant to be used in alternators so the operational heat in the alternator does not reflow the solder. Someone here will doubtless be able to confirm this or correct me.

[Citroënbender]

I sent the photo to a mate who mentors me in “everyday” auto electrical (he dumps the Frogs on my plate in return). A two word reply, “loose bolt”.

So he’s saying one of the heatsink diode frames was poorly earthed, the high resistance loaded it up and that’s actually where things started unravelling. Makes sense.

As the component mounting machine screws are all into through holes, I’ll use a wicking thread locker from the outside, and inside I’ll ensure is bright-clean with electrically conductive grease at the mating points. The rectifier pairs are costing about $130-ish all up delivered, half from Spain and half from Florida.

[slowsnake]

Is this car a very rare collectable CB?
And by that I mean is the alternator part of a genuine collector car, or just a "shopping trolley"...and can it be replaced as in exchange for a reco?
Or do you just like being overworked and overstretched and intent on turning your hair grey?.....like mine!......

[Citroënbender]

It is rare, not quite irreplaceable but getting close. None listed for sale on the usual sites. Most were cannibalised by kidults for their motors, 15-20 years ago. If it died a messy death I’d look for a Lancia Thema 8.32 to replace it, because I’m a masochist.