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. The engine cranks fine, just does not start.
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.
Please help. Thanks in advance.

 

I heard of this situation. These early-mid/late 1990s MB cars were very sensitive to battery charging, overcharging, jump starting, etc. Still are today, just most prone to problems during these years. Weird electrical issues have presented to me also, during alternator changes, battery changes, etc.

As you state, it could be damaged control modules in the computer module bay.Could be damaged relays/wiring/connections in the battery compartment.

Hopefully not. Try:
-Disconnect and remove battery.
-If not done already, clean all battery cable connections and look around the battery compartment for anything looking not right, including relay connects, and fuses, etc.
-Remove computer modulescover in engine compartment and while retaining order and direction orientation, carefully remove the modules and check connect pins for cleanliness/corrosion and integrity of any fuses on top of one of the modules.
-Carefully reinstall the modules.
-If not donealready, check all of the fuses in all fuse bay areas, includingany in the trunk above battery.
-If not done already, install new battery.
-Retry all operations. (as applicable, radio code reset also).

If it really is a now defective computer module item, at least now you know where they are located. Double check all possible fuses again and again.

All of the above steps, each one, has helped me through more than once occurence of electrical weirdness of my sensitive electronics MB car.