1985 Mercedes-Benz S-Class - Car overheating - what could it be?

My car keeps over heating.
I’ve flushed the cooling system and replaced the thermostat.
The radiator doesn’t seemed to be clogged and the cooling system isn’t leaking.
Any ideas?
Could it be the water pump?


Is the suction (mechanical) fan engaging?

water pump v belt tension good?

the water pump shaft doesn’t have play, does it . . . ?!

auxiliary electric (condenser) fan engaging? . . . I believe the auxiliary fan actually has multiple stages on this vehicle

coolant pressure cap seal is good?

coolant cap holds pressure? . . . you need a pressure tester to confirm this

are the fan shrouds present . . . and in good shape?

is this a diesel or gasoline engine?

have you verified the actual temperature with an accurate thermometer . . . a laser thermometer, for instance?

What does the actual coolant look like . . . ?

Looks like clean coolant?

Looks like milkshake . . . ?

You can use the laser thermometer to determine if the radiator is partially plugged . . .

I hope you bought that thermostat from a reputable vendor, and I hope it’s the right temperature rating. I’ve had several instances where aftermarket thermostats were faulty, didn’t fit properly, had the wrong temperature rating, didn’t work to the point of actually CAUSING overheating . . . .

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