2014 — 2018
2.0L Turbo (M274) - C300 Sport/AMG Line
Petrol
Cold start check: During your first inspection, ask the seller to leave the engine cold. Listen closely for a brief rattling noise for 2-3 seconds as it fires up, which could indicate wear on the cam phasers or timing chain tensioner.
Test the transmission: While driving, pay attention to the shift quality between 1st and 3rd gear. If you notice any hesitation or clunking, it may be worth checking if the transmission fluid has been serviced recently.
Inspect the coolant system: With the engine off and cool, check the coolant reservoir for any oily residue or signs of milky fluid, as early signs of thermostat housing or heat exchanger issues can be caught here.
Use the infotainment: Cycle through the COMAND system while parked. Ensure the rotary dial clicks firmly and the screen does not flicker, as these units can be expensive to replace if they start showing signs of software or display fatigue.
Time to inspect spark plugs and consider a transmission fluid flush to keep the 7G/9G-Tronic shifting smoothly.
Keep an eye on the water pump and thermostat housing, as these plastic components may begin to show their age around this stage.
A major milestone; you'll want to verify the secondary air injection system and suspension bushings have been inspected for excessive play.
Ensure the oil has been changed strictly every 10,000km or annually using high-quality synthetic oil.
Check for a consistent service history, preferably with a Mercedes-Benz specialist or authorised dealer.
Verify the brake pad and disc wear, especially on AMG Line models which can chew through consumables a bit faster.
Check the tyre condition for uneven wear, which might suggest that the wheel alignment needs a refresh.
Confirm the air suspension (if fitted) holds its height overnight to ensure there are no slow leaks in the bags.
Estimated repair costs if issues arise
While not guaranteed to fail, some M274 engines may eventually require attention to the camshaft adjusters. It is a specialised job, so it is wise to set aside some funds for a future mechanical check-up.
These components use plastic housings that can become brittle over time. If you notice a coolant smell or low levels, planning for a replacement is a proactive way to keep the engine cool.
To keep the Mercedes gearbox smooth for the long haul, a specialist transmission fluid and filter change is highly recommended every 60,000-80,000km.
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Disclaimer: This report is generated with the assistance of AI analysis based on verified automotive data. While we strive for 100% accuracy, enthusiasts should always conduct physical inspections and consult service records. View Full Disclaimer