I could never get the 240D up past the 80C mark on the temp gauge. Took out the thermostat (oem Mercedes 80 C) and noticed it is slightly open (about 1/16"). I put in an old 80 C thermostat I had laying around that looks and checked ok in boiling water and the temp gauge now sits at approx 84 C. Engine seems to idle better and feels smoother.

Autozone sells a Value Craft 192 F (89 C) thermostat that is made in Germany. Anyone with any experience good or bad with that thermostat? I have one on order and will try it out.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked