My 240 is.one of those that did not have a factory block heater. I didn't want to take the chance with the potential block issues and a huge lack time. I installed a Katz k500 hose heater. So.far it is a big difference in how it starts. Not quite like it Is 80 degs, but one glow cycle and she fires up.

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1983 Black Mercedes 240d rescued from a field in Pecos NM.
Kids named it Helga Die Benz.
Edgewood NM Territory