What are the typical operating temps of your 617 engines (highway travel) during cool/cold weather? Mine doesn't seem to rise much above 60C. The heater doesn't blow very hot air, and I have bypassed the ACC servo. This is my first winter with this car (1980 300SD), so I don't have much firsthand experience with it. I am considering blocking off part of the radiator to try to raise the operating temps (I'm also running the car on a WVO blend).

I suppose there's a chance that the PO removed the thermostat for some reason, does anybody have a suggestion for testing the thermostat operation without removing it from the car? I'll open the thermo housing if necessary, but I don't really want to make that big of a mess today.

Thanks for any input.

Steve.

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'93 190E/D 2.5 Turbodiesel 5-speed (daily driver)
'87 190D 2.5 Turbo rustbucket - parts car
'84 Dodge Rampage diesel - Land Speed Record Holder
'13 Ram 2500 Diesel
'05 Toyota 4Runner