I bought my first mercedes this weekend and brought it home. A 1976 450 SLC. As I drove it home I found 3 obvious things that need attention. The first was that the odometer and cruise control didn't work.

The two things that concerned me was the high idle while in park (engine cold and warm) it idled between 1000 and 1500 with a rare drop to about 800.

The second thing that concerned me was that the rpm's were between 2600 and 2800 at 60 mph. I counted the gears from take off and there were 3 (should be right for this car based on what I've read in that 3 speed automatics were prior to 1980.

any ideas or suggestions that anyone has would be greatly appreciated.

 

hi,
You've got an Air leak, to be blunt. If u can get some brake/clutch cleaner, spray a tiny amount around the engine. This causes the engine to raise the revs and should narrow your search. Also, look for split vacuum hoses etc