1985 280 SE Alternator
 

My alternator is really making a lot of squeaking noise. Last night the car would not start. Dead Battery. I charged the battery and had it and the alternator checked this morning. Both checked out OK. However, I can tell that the alternator is slipping and squeaking. Can I conclude that I need a new one? Also, if so, does anyone know the part number on the alternator for this car. I think it is 80 amp. By the way, the belt seems fine.

1985 280 SE (euro)

Check belt tensioner -- if it has failed, the alternator can slip and the battery will eventually go flat.

also, watch the alternator light at night -- if you get a dim glow fading in and out, the brushes on the voltage regulator are shot, and it need replacement. 5 min job with a screwdriver, just swap the regulator, or take the old one out and take it to an alternator shot and have new brushes installed. Bad brushes can be intermittant, especially working cold but not hot.

If the tensioner and brushes are OK, you probably have bad bearings, replace or rebuild alternator. With the belt off, the alternator should spin freely, no binding.

Peter