alternator wierdness
 

The first trouble I've had with my '86 190D since I bought it. It's 10F up here today, it started fine on 4 this morning (1 gp is toast) this is a high milage, +300,000 unit that does 750 miles a week commuting. Ran it through the carwash and drove it home, 1 1/4 hours through snow, slush, and salt. Just went out and no juice. Fresh battery, no idiot light during the drive, lights, heater, big sterio on, but the wiper was moving slower. Not much different from any other friday. any ideas?

I suggest that using a voltmeter across the battery you ensure that the battery is dead. I'm assuming you have checked the lights and they do not burn, meaning that it is indeed a dead battery rather than a starter problem.

With voltmeter handy, jumpstart the car and then check the voltage across the battery. It should be about 13.5 to 14.5 volts. If it is only 12 volts after the car is running then the alternartor is not putting out.

At that point it is most likely that the problem is the voltage regulator which contains the brushes. Remove the two screws on the back of the alternator that hold the voltage regulator in place. Remove the voltage regulator and observe the brushes. If they are both not shiny, then one of them is worn out, no longer touching the rotor.

You can get a new voltage regulator from fast lane on this site for $14.00. If the voltage regulator (brushes) is indeed the problem, feel of the rotor contact surfaces (slip rings) with your finger and see that the grooves are not too deep. If they are no more than about 1/16" deep then put in a new voltage regulator and enjoy.

Good luck,

Thanks, the fix is done. 1 brush was OK, local guy had the reg/brushes and all is well.