Grrr! :(
 

My 1990 300E has been overheating and had some odd voltage issues of late. I just spent $1000CDN yesterday replacing the belt, auto belt tensioner and viscous fan clutch and did a coolant flush, which were all recommended by my tech. 20 min later my car was overheating again and today my voltage went wonky again: my ABS light came on, my stereo flickered so I shut off the AC to reduce the draw, which helped. I replaced my altenator in October and it checks out...WHAT can I do? I am going back on monday to have them fix it, hopefuly free of charge. They cannot take out the new parts they claimed were the culprit can they? I need some firepower to come at them with, so please help

I have a stereo, subs and 3 amps, would a Capacitor help my voltage issues or should I upgrade altenators like RUN and others are doing/have done?

Hard to see the future is. But sometimes an electrical problem like this can be traced to corroded cables at the battery. I don't mean just at the connector posts, but further up inside the cable. I had a positive cable which looked great, but under the plastic insulation, about half the copper had turned to green powder for a lenght of 3 inches. You might also want to inspect the heavy jumper cable which runs between the battery negative post and the car chassis as well as the heavy cable which jumps between the chassis and the engine block. Now I don't believe corroded cables alone could cause the car to overheat; unless perhaps there was insuficient current to run an electrically driven radiator fan. All your high power stereo stuff should connect directly to the battery and not share any circuits with other gear. My old 68 AMC AMX had an amp meter in the battery circuit. One glance at the meter would tell you exactly what's happening in the charging circuit and battery. Today they just give you a meaningless light. Good Luck. Tod

Check ALL your grounds around the battery and alternator!
 

You may want to go to a "more powerful" alternator. I know the later 124's had the improved alternators. Do a search!

When does it overheat? At idle or while driving?

Did you replace the thermostat?

Sounds like you also have a loose and/or corroded wire somewhere.