I have an 1989 190E 2.6 I had the same problem it was a combination of a very clogged up radiator and the front aux fan, also might want to make sure all your fins on the radiator look okay mine were bent.....and man those cars just run hot! Ohhh and you might want to post this in the gasser section of these very fine forums...and if you need parts click on the link at top...Phil is a great guy.