Several mechanical concerns appear regularly in used Mercedes-Benz engines. Oil consumption is documented in M272 and M273 engines, often linked to balance shaft gear wear. Timing chain stretch affects M271 four-cylinder engines, particularly in earlier production years. Plastic coolant components, including thermostat housings and coolant pipes, degrade over time and may present leak risks in older units. Variable valve timing solenoids on newer inline-six engines can show wear-related faults. Buyers should request service documentation and confirm whether the engine has undergone any compression or leak-down testing prior to purchase. These issues vary in severity depending on mileage and previous maintenance practices.