good tomorrow! in advance: I was not sure if this topic belongs to the oldtimer or nfz forum (it is about an nfz-oldtimer)… and now to the problem: my daimler l508d (t2/model 309/”tanne/düsseldorfer”, motor om314, bj. 1976, ~300,000km) has fever. normally the coolant temperature is around 83°c (thermostat opening temperature), whether summer winter uphill below load/loaded or empty. for some time the temperature has risen to 90° (also relatively constant, no matter what operating condition, and no matter whether heating heat exchangers on or on), and the cooler has remained cold below. I then tried to narrow down the source of errors piece by piece: I changed thermostat and temperature encoders for new parts (doesn’t cost much), then the water pump tested (runs), the cooler decalcified/washed (even all good)…it all didn’t work out and I was pretty perplexed. at the end of the week I then got the nigelnagelneue thermostat once removed and see there: suddenly neat flow in the cooler, which was also warm down again as it heard, also the net was evenly warm – temperature overall of course not higher than ~50-60°c. then I drilled n few holes into the thermostat and made it again installed, car warmed up and a proper test: I live directly on the legendary Krähberg in the rear odenwald (some maybe from moped riding or the mountain race a term). uf the table laid” and my car with full gas chased up the mountain. temperature at ~75°c (so almost normal temperature), then descended naturally to ~50-60°c. what do you think is the problem? why does a new thermostat obviously not open? I have to drive next week with trailer after eating (total distance approx. 700km), pick up a ton of coal, would you do that in the condition? for the car it is actually “no big thing”: empty weight currently 3.5t + 1t charge ung = 4,5 t total weight. and the car is designed for 5t + 3,5t at the hook (total weight 8.5t). many thanks already for your answer, matha