Alternator help

[Mikeyworks]

I think I am having trouble with my alternator. I don't think it's charging.

When I start the car, the battery light on the cluster comes on, then I rev the engine and it goes out....then after about 20 seconds, it fades back on (flickering) and will fade out a bit when the revs go back up, but eventually the battery will drain down (especially when I am using the accessories).

What should I check on the wires to make sure things are hunky-dorry?  

I followed the Bentley to see what the deal was, and there is about 12V with a full charge to the battery, with no voltage change when the car is running, accessories on or off.

Help...thanks, Mikey

[fspGTD]

Assuming your A1 has a bosch alternator...

First, remove or loosen your alternator belt.  Then grab the alternator pulley and try and wiggle it.  If it moves, your alternator bearings are shot and your alternator needs a rebuild.  (If you are in this situation, let me know - I have a good used bosch A1 alt with "W" terminal for tach output sitting in the garage, might part with it.)

After you've made sure your bosch alt's bearings are good, remove the brush/voltage regulator assembly on the back (two small screws, can remove this with alternator installed in car.)  Wiggle out the voltage regulator/brushes assembly, and check the brush length.  Wear limits are published in bentley.  Chances are your brushes are worn down and then it starts arcing and you can loose charging and see the alt warning light glow and alt intermittently or stopping entirely working.  Replace your brushes.  A new brush set probably won't be as cheap as you'd think it ought to be.  

I mention the bearing check because it's important... Bad bearings can cause a lot of arcing of the brushes, which will quiclkly eat through a new brush set in no time flat.  IE: matter of weeks.  On good solid bearings, a new brush set should last 200k miles.

This information may not apply to a motorola alternator, but I think all the A1 TDs came with bosch alternators so I'm guessing that's what you've got and that this information may prove useful to you.  Good luck.

[vwwv]

Mikeyworks, your charging symptoms sound exactly like mine (see earlier post re: battery light on by vwwv).  Jake Russell's response sounds good to me.  I have not replaced the brushes (my regulator is Bosch) because when I changed out the regulator from my '90 to my '86, the same symptoms persisted.  Jake's suggestion that the alternator bearings could be worn and causing the brushes to "hop" is something I hadn't thought-of.  My complaint started on a trip just a day or two after I had the belts changed.  Did the mechanic overtighten the belt putting extra pressure on the bearings and hastening the demise?  Or, was it just coincidental?  I was out last night and I ascertained that my batttery light flickered and/or went dark depending on my speed.  I also noted that if the light was on, I could extinguish it by shifting down.  Was I modulating the belt pressure, I don't know, but I sure am going to check the pulley play tomorrow.  Heck.  I didn't want to get an alternator.  I was hoping just for brushes or regulator.  I guess 225k milles on the original is not too bad?  I wonder how many revolutions of that alternator that would be?  Thanks to Jake Russell and to you Mikeyworks for the info.   Paul

[Mikeyworks]

I will have to check the play in the bearings this weekend. I would love to do it one night but with the end of daylight savings time and my garage being temporarily held by a cabby shell (gracefully donating it's floor to my caddy) I cannot work in there either. Hopefully the Cabby will be out by this weekend!!!

Thanks Jake and all!!!!

Mikey