A few weeks ago, I had to replace my water pump due to leaking at the weep hole. While there, I also replaced the thermostat. Both items were oem Mercedes. Since then my operating temps have increased by 8 to 10 degrees C. I used to run 85 when driving and 90 at idle. In extended stopped traffic it would creep up to 100 but not higher. Now the thermostat starts to open at 80 and will settle in 85 to 87. At idle it will go 95 to 100 and as soon as underway drop immediately to 87 to 90. This is all without air running. If I turn on the AC, at idle it will soot up to 105 and kick on my aux fans.

The viscous clutch seems to be functionally properly, aux. fans, etc. When I check the radiator it is hot at the top and gradually cools down toward the bottom hose. I appear to have good flow and you can tell when the upper hose gets hot and the bottom one warms up but is much cooler. This would seem normal and the radiator is working ok? What could be different since the water pump and thermostat replacement? Is the thermostat working properly or should I further investigate the radiator? System was flushed last year, and I replaced the coolant again when I replaced the pump with a 50/50 mix of MB coolant. What would indicate proper t-stat operation and radiator functions?

Any advice would be appreciated.

Thanks, BDBENZ

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87 560 SL
93 300E 2.8
91 300CE-24