I live in the southwest where it's "hot". Average temps above 110.
My '77 450SL with 95k miles is overheating during my commute from Yuma to Lake Havsu City AZ approx 150miles. I have taken it to several shops in the area non of which are MB dealers. I have had the radiator and thermostat replaced, checked for proper cataletic converter flow and still have this problem. What can I check next?

Thakx
MY450

does the heater system work properly? i have seen some that are not working, that caused similar issues, would have an air pocket in cooling system

can cause overheating. if it is too retarded. this also would be accompanied by poor power at higher rpm and perhaps backfiring.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Does the car have a viscous fan clutch (VFC)? If it's not hooking up properly under hot conditions, that will cause high running temps. The VFC in my 95 S600 spun the fan while hot, but the fan could be stopped very easily with a length of rubber hose. With the engine shut off, I was able to spin the fan too easily. It should have been much stiffer. Once I pulled the old one out, I could see that much of the oil inside the chamber had leaked out. I replaced the VFC, and now run no hotter than 105 C in stop and go traffic with AC on and ambient temps of 100 F. It usually runs around 87-90 C now, where before it shot up to 120 C even when cold outside.

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1995 S600, 1 of 618 (sold)

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What is the temp gauge reading when you are overheating? It might be running hotter, but not actually overheating, at the red line on the gauge.

Best Regards,
Jim