I'm looking at buying an X253 GLC63 (pre-facelift). I plan to keep this car for the next 3 years and drive ~35k miles. From my research these are some of problems that come up over this period, however these is not a lot of data for how common these issues are. Owners, how common are these issues? Which should I realistically account for and which are rarer? Debating between this and a S63. Really want an AWD AMG. Or an AMG that is drivable in the rain(I live in Seattle)

What are common issues and repair costs you have dealt with?

Issues that I can find that may happen:
Airmatic Leak/Airmatic Compressor Failure
Turbo Oil Supply Line Leaks
Turbocharger Failure (one or both)
Coolant reservoir tank crack
O2 Sensor Failure
Front control arm bushings / suspension components
Motor Mounts Collapse
Valve Cover Gasket / Timing Cover Oil Leaks

Would you get a warranty for this, even if some stuff like airmatic may not be covered?

I have a quote for a warranty for $6k that excludes the following and covers everything else:

Pre-Existing conditions are not covered (all parts covered under this Agreement must be functioning properly and not in need of repair at time of sale of the Vehicle and this Agreement). Repairs required because of collision, abuse, overheating or operation withoutproper lubrication or coolant, road conditions, misuse, negligence, alterations, racing, accidents, fires, floods, riots, acts of God, vandalism,upset, theft, lack of reasonable and proper maintenance, abuse through towing or improper load capacity, abuse through continuedoperation of an impaired Vehicle, or any other losses normally covered by casualty insurance.Also not covered are excessive oil consumption, loss of compression, and/or gradual reduction in operating performance due to failure ofa covered part or parts. Repairs beyond those required to correct the covered failure. Repairs of components which have been modified or added to the Vehicle after purchase, any repairs on Vehicles whose mileage has been altered or whose odometer has been tampered with while owned by You. Repairs made outside the 50 United States, its territories and possessions and Canada unless You obtain a written waiver from the Administrator. Any manufacturer’s required maintenance. Damage caused by Your failure to take or cause to be taken reasonable precautions to prevent further damage when an apparent problem exists. Diagnostic fees for non-covered repairs and non-emergency repairs performed without the Administrator’s approval.

MECHANICAL: Refrigerant, coolant, and fluids unless required for a covered repair. Service adjustments/cleaning, throttle body assembly (except injectors), contaminated fuel, fluids, and filters; air conditioning recharge, battery/hybrid battery packs/battery cables, bolts and fasteners, belts, dust boots, dust seals, hoses, brakes (front hubs, drums, shoes, lining, disc rotors and pads), exhaust system (including catalytic converter), filters, lights (bulbs, sealed beam and lenses), lubricants, manual clutch, pressure plate, throw-out bearings, clutch master or slave cylinders, manual clutch disc, strut inserts, shock absorbers, spark/glow plugs and wires, squeaks and rattles, rust, tires, tune-ups, wheel balancing, wheel alignment, wheel studs, wiper blades, shop supplies and hazardous waste removal. Repairs due to water intrusion, corrosion or carbon buildup. Repairs, retrofit, or replacement of any components caused by or due to compliance with any law or legislation including the Clean Air Act.

EXTERIOR: Service adjustments (glass and body parts), bright metal, bumpers, body panels, handles, door handles, hinges, glass, moldings, outside ornamentation, convertible or vinyl tops, paint, rust, sheet metal, sideview mirrors (glass and housing), air and water leaks, weatherstrip, wheel covers/ornaments and wind noise. Repairs due to water intrusion or corrosion. Physical damage, alignment or bumper and body parts.

 

One of the scariest issues with the M278 motors is the oil system starving the pistons which results in cylinder scuffing. These are aluminum engines and the cylinders are NOT SLEEVED...they are coated (an anodizing chemical is used to harden the cylinders...but it's only fractions of a millimeter deep...so it doesn't last if the engines are starved of oil). The oiling system uses a two stage pressure switch. Under 3,500 RPM, the underside of the pistons are not bathed in oil...this is to make the engine more efficient...Above 3.500 RPM, the oil pressure switch allows full oiling. You can see damage usually on the #5 cylinder. Pulling the spark plug and inspection via a borescope is the easiest method. Following Mercedes 10,000 oil change interval doesn't help matters much either! There's not a mechanic alive who agrees with that oil maintenance schedule...And unfortunately, this would qualify as a "pre-existing issue"...so it wouldn't be covered by your warranty...and there is NO FIX...other than a complete engine replacement.
Also look for oil wicking in the cam sensor wiring harness. Again, pre-existing condition, so if you see it, don't walk, run away from that $10,000 disaster!
Look for all maintenance records. If the original owner changed oil at 5K or 7.5K miles, you're basically golden...if they only did it every 10K miles, be very hesitant and take it to a qualified mechanic...make sure to mention cylinder 5 scoring....
Good luck!

 

thanks for the reply! IIRC this is the M177, does this engine have the same issue?

 

No, but definitely research the m177, generally regarded as pretty great.