Rough Running '76 450SL
 

I went to look at a 76 450SL today that the owner is selling pretty cheap. Owner says the car started running rough recently , it has 122k miles,on it, and he doesn't want to put any effort or money into finding out why. That always throws up a red flag for me but I figured I'd ask the forum if there are some common things I can look for that would cause this. The car runs but you can hear it is not running smoothly and if I push on the accelerator it revs up very slowly and the miss does not go away. If I had to guess I'd say at least 4 of the 8 cylinders aren't operating. The car is pretty clean otherwise so I'd like to pick it up it this can be fixed for a reasonable price. Any ideas? Thanks

if you are sure it's really 4 cyls missing, i'm betting the timing chain jumped and possibly bent the valves on the driver's side head. they will jump up to 4 teeth, run like crap and NOT bend valves. could also be 4 leaky injectors, 4 bad plugs or 4 bad wires. but, 100k is about the limit for the timing chain and 122k is well past, assuming the odometer still works. could be a bargain. if the valves aren't bent, it's not a bad job. you have to pull the valve cover on both sides to be sure. good luck, chuck.

This is just the sort of situation that would make a pre-purchase inspection by a knowledgeable MB indy well worth your while. Welcome to the forum.

I believe the '76 has the electronic fuel injection (Don't know what you call it). There are 2 sets of points below the ignition points that control the timing of the injectors. If they get dirty or oilly, the car will run bad. Usually just need a cleaning.
I'm sorry of I have my years mixed up but maybe someone old like me may remember.
Paul