I just got a 1983 380SL that I picked up in California and drove home to Missouri. I got the car and drove it the few blocks to my daughters home in Murietta. It ran very rough. Then it would not start. I traced this to the ignition coil, no sparks at the coil or plugs. Replaced this and drove home to MO. Took it to my Mechanic to get it ready for inspection and find the rough run and idle problem and again it would not start. Incidently, this was a 3 day trip and I stopped and started the car at least 20 times.
As it stands right now, it starts sometimes and sometimes not. Plugs and plug wires have been replaced and when it runs it runs smoothly but idle might vary from time to time from 500 to 1200 rpm.
Also, I noted on the drive home that the tach was very erratic. It would go along for awhile at 2700 at 70mph (this is a 4speed) and suddenly go to 3500 to 4000 but no rpm change had occured with the engine. Then just as suddenly it would retlurn to the 2700 mark. Right now with the engine running, if you tap the horn the tach goes bannanas. There is a MB service bulletin that addresses the tach and notes that the starting problem I am describing could be the tach. We have checked all pertinant voltages etc and now need to disconnect the tach to see what happens. I am assuming that these tachs have some kind of overrev protection and that this might be malfunctioning.
A tach is a $400+ item. Is it possible that we are overlooking something. I would really appreciate some input and suggestions from my MB friends. I read with interest BILL17s post regarding a similar problem. I havent looked at the interior capacitor, could this be the problem, hmmmmm! Thanks for any help, Lee


Thanks Lee