My 300SDL is running at 100 most of the time - even a little hotter when
climbing. There was a new thermostat installed, but the car continues to
run at 100. The overflow radiator cap was replaced because the old cap had
broken apart - rubber hard, spring broken. The new cap, purchased at
Autozone, is supposedly rated at the same pressure as the original. The
overflow was originally filled too high and I have been losing antifreeze
out the overflow tube, but the coolant level is now where it should be.
Three years ago, both the radiator and auxillary fan were replaced.
The air conditioner is fully charged with freon but only works
intermittently. I was told I needed to replace the kick down relay and
that would fix the problem. I purchased and installed a new relay, but it
does not act any different. The compressor comes on for maybe a minute or
two then switches off.