240DieselDog,

So, the coolant system design suffers a loss of capacity when you take the thermostat out, as noted above. And the shroud is really a duct that ensures the energy being consumed to drive the engine fan actually makes the air go through the radiator and remove heat from the coolant circulating in the engine. And, in spite of what you have done to your car, it still runs within the normal operating temperature range. I think your treatments must be keeping the rest of the system operating at peak performance, which is adequate for the engine to keep its cool.

All this goes to show that from the factory these cars had excess capacity. I have noted in the past they always run at a dead 175*F, or just under 80*C no matter what the outside conditions, speed, slope of the road, etc when they are new. The fact that this changes means somewhere capacity has been lost. I am aware of the manual bold letters above saying it is ok to run just under 120*C, but I grow nervous when I see the needle on the gage off its previous invisible rest or peg. I think another good flush is in order on my 240D.

The other cars, gas powered units and my E300D TurboDiesel, have always been a little easier to get to run over the 80*C mark in stop and go traffic, especially in the summer.

Hope this helps, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)