Have an 86 560 SEL, have just changed radiator, fan clutch and thermostat. Aux fan is working properly. If car is sitting in park with A/C on in 90+ degree weather, temp goes to 100 (line above 80 mark) and stays there. When I then take the car on the parkway. driving at about 65 mph, temp goes up to 110. After about 10 minutes of driving, temp gradually drops back to 100. If I shut the car off for only 5 minutes and then resume under the same conditions except for local driving temp gradually goes to 100. Upon entering parkway again, temp goes up to 110 again. When I get off parkway, temp goes to 100. Additionally, sometimes as I'm driving locally temp gauge will occasionally go up to 105, back down to 90 etc but does not rise when standing still but increases when moving. Could new radiator be defective? Bad sensor for guage? Any suggestions would be appreciated.

You could have a faulty new radiator although rare I have seen it before. Also don't forget that it could be the gauge or the sensor for it. Have it checked.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Had radiator temp tested with dash gauge at 100 (212F). Center of radiator read about 175, sides read about 190, thermostat housing read 205. This gives me the impression that both gauge and sensor are accurate. Is this normal for the radiator?

I was thinking about this the other day. Did the neck break off of the radiator? That is the most common failure. I was thinking that it may have an obstruction in the system somewhere. The other thing is possibly a bad thermostat out of the box? Can your technician help out somemore or is he out of solutions?

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM