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 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Why not just get an OEM thermostat?

- Peter.

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2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S

Replace your temperature sender.

Why? Because OEM does not offer a stat higher than 80 C and I want the engine to run hotter, especially for winter time.

FI, why should I replace the temp sender? I have no reason to suspect it's bad. Temp senders are very simple and rugged devices and I have never seen one go bad. I don't like to replace parts iindiscriminately.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

The engine was designed to run at 80*c, running hotter will affect longevity. I doubt many people can handle 180*f heat from the vents for long without turning it down, 192*f won't do much better and it will not make it heat up any quicker at all.

If its more than 10 years old its likely not as accurate as it should be. Temperature cycle stress, wear and corrosion reduce its accuracy significantly over time. They rarely fail outright but they do get reading "off" over time.