It's summer in Texas bouncing off 100F but I don't remember my 350SDL's engine temperature gage moving around a lot between 90C and 110C. At one point during
a long haul up a hill at 70 mph, it stopped just short of 120C ! The radiator and
thermostat were replaced within the past 6 mos. and coolant is at proper level. Could
it be the dual fans or something more ominous? This unit has 126K miles and does not
use any oil (yet) and I am aware of the potential for a short life span. Still a great road
car !

 

The auxiliary fan should come on at 105c. Check auxiliary fan motor, and thermo switch that activates it.

 

Thanks for the advice as it's obviously pointing in that direction as I pulled the car over yesterday once the temp gage hit 100C at 70 mph (it stays around 90C at 60 mph), popped
the hood to find only one of the dual fans working. Once the car is stopped, the temp. increases about 5 degrees due to the lack of air flow I'm assuming.

 

Yes, it is normal for the engine to rise in temperature after exiting a highway etc, but should cool back down within a few minutes of 30 mph driving.

 

You could possibly have a radiator partly stopped up due to electrolices breaking down the aluminium heads. They make radiator additive used to help this from happening.

 

Do not run that engine hot there bad about blowing head gasket.