The coolant on my 1985 300D stays at about 95 degrees C. It used to be about 90 degrees C, but increased when I replaced my thermostat and changed to Xerex G05. Thanks to comments on a previous thread, I think that I have successfully burped all of the air out of the system. The other day I ran the car up a long, steep grade during some hot weather and the needle only went up a few degrees, so it seems to be cooling OK.

Is a coolant temperature of 95 degrees C within acceptable limits? I think it runs better at the higher temperature, but I don't want to do anything to shorten the life of the motor.

In hot weather, that's about right. If you have the A/C on, going up a hill, I'd expect it to hit 100. Mine stays about 85, but I'm not using the A/C, not driving fast, and have a new radiator and rebuilt engine.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

95 that is where my 85 300TD runs almost all the time. My thermostat was also marked 85 degees. My car prior to the thermostat replacement ran below 60 consistently. After the thermostat was changed out my mileage ment up about 2.5 MPG at the higher temperature now it is about 29 MPG.

Mine seems to run hot-close to 100 if its 85* or hotter. If its 95* with AC, it goes over 100. I just ordered a new temp sender(Iunderstand they can go bad).

I really would like a 70* thermostat.

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1983 300TD, white, 240k
PAY TAXES ON ELECTION DAY!

Mine was running quite hot this summer until recently when I changed the lower radiator hose and in the process integrated about 3/4 gallon of new coolant (approx 60%water40%antifreeze) and I also changed the pressure cap on the expansion tank from the worn out crusty original one to a brand new "1.4bar" version from fastlane....temps have been now stayed around 82-83C, vs 85 normal before, and the highest I've gotten it now on a hot-day freeway run was barely 90C, so I think my changes made quite an improvement...it used to maintain 95-100 on the freeway, and 105-110 on hills.....

In the hills of PA in June when I had 600lbs of cargo, nearly full fuel tank, and my friend and I in the car, I was chugging up some of those hills, pedal to the FLOOR in 3rd gear(S), and I was barely making 40-45mph.... Temp nearly went to 115C on a couple of those climbs....and I could see my exhaust billowing behind me too.....it survived it though, and whenever I'd go down a huge grade after the climbs the temp would fall very quickly as low as 80C! It was very interesting. Mileage in that area came out to around 18.3mpg.... Later on it skyrocketed back to nearly 27 once I had flat road again....

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-diesel is not just a fuel, its a way of life-
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