I have an '84 500SEL Euro with 191,000 miles on it. I love the car but an overheating problem has plagued it for years......only, however, in stop-and-go traffic on a hot day. Driving in Atlanta in the summer is an adventure. I've only been in the red once (and luckily reacted quickly enough), but the temp always gets to 110 during the summer months. 110, by the way, is what the factory manual states as a perfectly normal operating temperature in hot weather. The problem is that if I am stuck in traffic for very long the auxillary fan will eventually lack capacity to hold that temp and it will head to 120 (red). To date every possible component has been replaced, every check has been made, and every additive has been tried...to no avail (please take my word for it). Experts have repeatedly tried and failed to find a "solution". All I can do is rationalize that I would have put all that repair money into the market and lost it anyway. I have always referred those very experts to the factory service manual which contains a statement suggesting the car be shifted into neutral in stop-and-go traffic on hot days in order to preven the transmission from causing a build-up of heat. It is obvious to me that even mercedes recognized that cooling may be marginal in these models under certain conditions, or why would they even suggest such a thing.
I've heard that replacing the engine fan with an after-market electric fan, which obviously produces more air across the radiator at idle, can fix the problem. I've also heard that a custom, more efficient radiator can be made. I would greatly appreciate any help, if anyone has any ideas. Maybe someone out there can find a solution for all of us.
Thanks so much.
Don's 500SEL Euro