My '90 300E seems to run at around 60 to 70C most of the time. Over the last couple of days I have seen it hit 80C a few times while idling in traffic. This doesn't seem like anything to be too concerned about to me, my Porsche runs at about 80C, but the wife swears it is running a little hotter than usual.

Any of you out there with this car - what is the normal operating temps range for yours?

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Andy_M
'98 W140 S320 Black/Black
'06 W164 ML500 AMG White/Grey
'03 Porsche 986 Midnight Blue/Grey

60 to 70c is low, not good at all. This will lead to carbon deposit due to incomplete combustion. MBs usually run well between 80c-95 when the thermostat and cooling system is working properly.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT

Should have an 80c thermostat.

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Bill

Backyard Shadetree Mechanic, 30 years running.

1987 300TD
1988 300E (sold, sniff)
1999 S320
1981 Volkswagen Rabbit Truck (Diesel)
2001 Ford Expedition
1988 Suzuki Samurai
On my list to buy: R129, for me, and a R107 for my wife.

If the T stat is stuck open the temps will never reach opertating range.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT

Thanks Guys. That pretty much confirms what I thought, weak thermostat.

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Andy_M
'98 W140 S320 Black/Black
'06 W164 ML500 AMG White/Grey
'03 Porsche 986 Midnight Blue/Grey

Normal thermo for that chassis is 87C...