overheating or not? (1985 500SL)

[ianh2]

Hi all. I have a 1985' 500SL, in the UK.
I had noticed that the temp gauge sat over the 80 mark (87 - 90?) in normal driving, periodically, going as far as 100 up a hill, or in traffic, but settling back down. Up and down as load dictated.
Thought - mmmm, is there a problem?
So, just had her sat at idle with heaters on (nice and warm) -
After 10 mins, gauge showed around 85 degrees with top radiator hose warm and lower one cold.
So, turned heating off -
gauge rose to 95 - 100 quite quickly, but then fell as i placed some load on the engine. I thought she would overheat, but she didn't.
Initially, top radiator hose warm, then hot,
lower hose cold, them warm, then hot.
temp gauge back to it's 87 - 90 state.
I was aware of how quickly the temp fell, so assume that that was the thermostat opening? Seems very late?

Can I assume all is ok?
Is this another case of replacement thermostats running nearer 100 degrees?
The radiator is a recent replacement from Mercedes. Is it feasible that, at idle, with heaters on, the engine does not get hot enough to circulate coolant to the radiator?
All and any advice welcome....

 

[television]

The Visco fan cuts in at 80C and your electric one (if fitted)at 100c as long a the temp does not go above 100C it should be OK

If Visco only do the carrot test at 80c and see if it chops it up