W123, Factory Books and Manuals

In adjusting my valves on my 300D nonturbo I am perplexed with an odd occurence. After adjusting a valve to the right gap and tightening the lock nut and adjusting nut, I check the gap again and all is good. But when I use a wrench to spin the valve stem using the two nuts, which turns the valve stem and the spring assembely, the gap changes, even though the nuts are tight. It will get either tighter or looser, but if I keep spinning it it will return to my original adjustment. That is if it gets tighter, by spinning it further it will eventually loosen up.

What is the normal running temp for my 83 300D? Right now it gets hot quickly and moves up above 90C and will approach the 120C point if I run the AC. I've changed thermostats and flush the radiator and put in new coolant along with a water wetter. Seems to run somewhat cooler but not what it should be. The electric fan used to come on but doesn't now. What is the most common thing I should look for if the fan doesn't come on? Thanks, Dan

I have an '82 300D and am trying to remove the ignition lock and switch. The key will still usually turn to all positions. I read that the key has to be in position 1 then a wire is inserted and the lock is unscrewed, but I am a little confused about that part. Any help would be appreciated.

I have never really understood, on our 123's, why I have to return the key all the way counter-clockwise if the engine fails to start. Strange voodoo with the vacuum shut-off? A peculiarly odd tuetonic accomodation for the hearing-impaired? What prevents it from functioning. Every now and then I have trouble with the switch stopping before the crank position, no matter what I do. Is this something that popping the cylinder and spraying WD40 would help? It is so intermittent that I could go for weeks without it happening again, or I could get stuck at the drive-up tomorrow. Thoughts?