I have a 1991 Benz 300E 3.0l that had a fried battery and would not start after that. Prior to this incident, I had changed the voltage regulator on the alternator and my guess is that it failed and overcharged the battery to the point where it just boiled over all the acid in had and possibly damaged some electrical components including relays / sensors etc .... I do not know what exactly.
The battery was hot and litreally empty with caps blown away and heavy rotten eggs smell. I Called in AAA, filled up water and got a jump start and then drove a littl bit trying to get to the workshop. Car started heating up and the fans would not get turned on so I parked the car at a friends place for 3 months as I was away from home. The power seats were also not working. .
I finally managed to get the car towed back home to my mechanic who has only been able to start the car couple times in past three months. When it started it ran fine (not driving, just ideling) and when shut off it would not start agaian. Everything seems to be fine including spark, compression, fuel etc.
Did I fry something that is stopping it from starting. I love this car and would like to keep it as long as I can. Pls let me know how to go about solving the problem eliminating one thing at a time.
Please help. Thanks in advance.

 

The symptoms do sound like a defective voltage regulator as far as the ability to start the car only to have it dead upon shutdown I also experienced this problem and after replacing the regulator it immediatly stoped this problem. The overcharging sounds more like a bad starter as the voltager regulator usually results in the engine shutting down due to the loss of contact with the worn carbon brushes. It is not impossible to have a regulator brand new that is faulty and at $30 it is worth a secondtry.