190E Overheating Solution
I have a 1986 190E 16V--with 81,000 miles. Like many of you on this forum, I have had overheating problems in stop and go traffic. I finally found the solution--at least for my car.
I won't bore you all with why it took me so long to find the solution--I guess old age just makes you slow.
In my case it became apparent that the fans were not coming on at the correct temperatures. The main fan would come on at about 115 degrees C, the aux fan above that. I couldn't believe that the problem was the temp switches, so I checked everything else--and everything was functioning.
I ended up replacing the thermostat ($12) when I changed the coolant. I think it never fully closed or opened, so I wasn't getting full flow.
I then changed the temp switch for the main electromagnetic fan clutch (about $18) and the temp switch for the aux fan ($24).
Now the car does not overheat. The main fan comes on at 100C like it should. The aux fan comes on at 105C like it should. Car does not get above 100C in any traffic. I have yet to test it on a hot day with the A/C on, though, but I have confidence now.
I guess in a 16 year old car ANYTHING can be bad! You can easily check the other parts of the circuit for operation by removing the plug from each of the temp switches and shorting out the terminals. The appropriate fan should go on immediately. If it doesn't, then something else is wrong in your case.
Good luck to all you overheaters!