Failed alternator? (Help!)

[BigggWilly]

Hey guys,

So just today as i'm driving into the city I notice that my battery light is slowly getting brighter, as i'm steadily driving at about 3000 rpm. At the first stop I come to, as i'm idling comming to a stop, but tach drops from 2000rpm to 0 instantly, and the battery light comes on at full brightness. When I rev the engine, the tach jumps from zero to whatever the correct RPM (as long as its above 2000) and then back down to zero when idling. I checked the belt and it shows no indication of slippage.

No, after about 5 minutes of driving like this, the problem seemed to fix itself. But then it came back after another five minutes. So I went about my business in the city, stoping and starting the engine a few times throughout the day, same intermitent problem. On the way home (at night, in the dark) I noticed that I could "fix" the problem, albeit temporarily, if I held the engine at 3500 rpm for a few seconds, as the battery light fades, and then turns off, and the headlights "click on" to full brightness.

Now here is my prognosis. Since the headlights are dim as the battery light is on, it would indicate that the charging system is not working properly. Also, a crazy tach also points me to the alternator, so I figure I my alternator has died.

So I guess my question is: Does this sound like a failed alternator? Is there a part that I can fix/replace, or should I just bite the bullet and get a new one?

Thanks very much for your time as always!
Will.

[fspGTD]

Your diagnosis sounds right-on.  

I'd bet that your brushes inside your alternator are worn out.  When it happens IME, you get intermittent battery light and it can be somewhat random and the outages can manifest as heat-related too.  It will progressively and quickly get worse.

You could at least buy yourself some time by getting new brushes and just installing those.  Unfortunately they are a little more expensive than you might think they ought to be!  You can install them (assuming you have a Bosch 65 amp alternator) with the alternator installed in the car.  There are just two little screws holding them in.

I would highly recommend loosening the belt and giving the pulley a good wiggle at this time to check for excessive bearing play at this time.  If your bearings are shot, your new brushes will arc and wear out really really quick.  And have I mentioned they are not exactly cheap.  If your bearings are in good shape, you should be good to go with just new brushes.

If you find the bearings are shot, then it's time for an alternator rebuild.  If it comes to this and you need a 65 AMP Bosch alternator compatible with diesel non-A/C fitment, let me know as I've got a very good condition and low miles since rebuilt spare that I wouldn't mind parting with at a reasonable price.

[moosiah]

So  I had the same problem w the frankenbunny ...  I went to the local Napa ( I know ,,,, Sonoma makes wine Napa makes auto parts..)  dealer who's pretty sharp and he could not find a part # for a 65amp "down " alt .... so I tried Jordans in Santa Rosa ...... the boss hisself  couldn't find the right one in stock either  :cry: ........ BUT he did have a Bosch regulator/ brush holder in stock for $20  ...... that fixed it for now,,, and i'm looking for a spare-for-rebuild now.  :wink: I guess I'm back to haunting picanpul if I ever get a day off again.....  :lol:
Joe that sold me this car just made a big angle iron bracket that reaches around the alt to grab the ajuster bolt from below..... ugly and uses the common "up" alt that he already had  :twisted: easyly fixed on one of his trips to Mexico/ Baja.......