W126 Temperature

[drosen]

Regarding a 1990 300SEL

When I first got this car, the water temperature would usually stay at about 80 (C). In very heavy traffic it would sometimes go up to just under 90, after which it would suddenly drop back to about 85 - I assume that was because the fans came on.

Recently I had the dealer flush and refill the radiator, and install a new thermostat (don't ask - $250!!!!). Now on vacation I see it runs at about 85 and in traffic it went up to a little over 90 and didn't come down until traffic started moving and I was driving at 65mph for a while. Scared me, I was just waiting for a hose to burst or something else bad to happen from all that heat.

Makes me wonder what the dealer did and if the fans are still working.

Any thoughts from anyone, and how can I test the fans coming on at the right temperature, whatever that is....
Thank you.