I am hoping for help on a 600sel issue. I recently purchased a 92 600sel (85,000 miles) which died on my drive home. The dealer I bought it from in Chicago felt terrible and agreed to fix the car and ship it to me. They replaced the mass air sensors and the injector harness and shipped the car to me. It ran great when I got it, but withon 30 miles it started to run terrilbly rough and lacks power so it barely moves. I took it to our local authorized Mercedes dealer in Joplin, MO who diagnosed it once again as mass air sensors. These were replaced only to have the same issue arise within 30 miles. I took it back to my dealer who much to my surprise said the problem was "over his head" and he refused further service on the car(I didn't know such a response was possible). I have discussed this with several sources who indicate the most likely scenario to be the main wiring harness causing mass air sensors to short out. The injector harness was recently replaced. I do not get a check engine light. I plan to take this to another dealer who assured me had worked on 600 series cars and could replace the harness if need be. However I am afraid to take a hit or miss approach on a repair that is this expensive. Is there anything else this may be or is the harness the most likely suspect.
Thanks on advance!
Jon

 

jon, this is a famous problem for early S600.

replace the air mass sensor wiring.

replace the crankcase ventillation pipe (previously it is made of duro plastic and gets broken, now it's metal).

replace the intake manifold gaskets.

the throttle valves wiring is also a bad quality. if you will slice it and see the inside, you'll get surprise to see the inside insulator crumpled on a slight touch.