So I’ve got a 1991 240 Wagon with about 180k miles
the Alternator has been making an audible rattling from inside of the cabin area since I got the car (can also be heard and felt directly at the alternator)

the thing spins freely but the bearings are obviously going out. The alternator is the Bosch OE part (the regulator is new but also Bosch)

It puts out a range of voltages, from 13.4 with all electrics on to 14.2 with all electrics off (13.8 with only headlights on)


My questions are:

1. Is this a normal expectation of voltages?
2. What is the thing, circled in the photos? as my alternator does not have this

I know I will be replacing it sooner rather than later but I need to get by for now and I will need to know what to look for when buying a replacement.

 

So as I have found the box on the back is a radio suppressor/condenser and not al alternators have one. In case anybody else has this same question, what it does is basically act like a capacitor. The voltage spikes and drops form an alternator due to the fact that it is AC current. That means that there are 2 electrical fields that are slightly out of sync because at the peaks and valleys of the waves in the electric fields there are small gaps causing that wave to be segmented. They are out of sync so that there is always a constant source of power being generated. These gaps still exist however and what the condenser does is store a small amount of electricity so that these segments are filled in even more. All that being said! if you have one on your alternator great, if not great. Wont make a difference with it charging, but you may hear a ringing type feedback if you have an old school radio I the car (new radios have these things built into them)



So someone out there please let me know what real world output you are getting from your alternator. Both the volts and amps if possible.

 

amps is totally dependent on load.

you should see a solid 13.8-14.2V at the battery, when the alternator is working and the battery is fully charged. turning on a lot of loads like high beams, will possibly drop a few 0.1 at idle but if you give the engine even a touch of gas it should catch right back up to the full 13.8-14.2V