Alternator 'heads up'

[C Sean Watts]

With winter upon us, I like many others, suffered the 'old battery = no start in cold' thing. Turns out the battery was almost 8 years old so I don't feel so bad. Just for easier sleeping I pulled the alternator to make sure I didn't cook the rectifier or anything else. It was good; made 14V, ripple = 0.8V, no burned or 'leaking' diodes (they hold water?), no oscilloscope but also no indication of lost phase(s). BUT.....

Since we have easily removable regulator/brush assemblies I pulled it off and saw what 156K miles does to brushes - The original part number = (as seen on back of transistor) NEW part no. ***for 80 or 140 amp BOSCH - alternator = 1 197 311 225 (Valeo may be different)*** {if you notice the width of the brushes in the comparison are not the same - good eye, that's for an Audi but the length is what I need to demonstrate}

*NB* - They must make a straight/square connection on the commutator part of the rotor. I had to file mine very slightly to stop if from seating cockeyed. (look at the short brush and you'll see why)

I went from 12.45V to a rock steady 14.1 at the battery at idle.

My hope is some fellow forum members will read this and NOT have to buy a new alternator if it's not totally bad...

[Jack Dabsy]

Excellent topic
Annoying to hear when people change the whole unit when its just an easy fix !