My dads 560SEC is overheating. We have replaced:

Fan clutch
Waterpump
Themostat
Coolant, 50/50 mix (3 times for each of these jobs)
The Radiator looks relatively new, but i could be wrong. But we have washed it well with the hose a few times.

After all these replacements the car still runs hot, without the AC on and under normal operating loads. The problem gets worse when stuck in traffic at and idle.

The Aux fan does come on at 105 degrees like it should, even so the guage still reads 105 degrees or more. Could this be the guage sensor, or is there something im missing?

~mark