2009 MERCEDES-BENZ S600

Typical onset: 60,000-100,000 mi

Symptoms: Metallic knocking or ticking from lower engine, Oil pressure warning at idle when warm, Metal shavings or glitter in oil during changes, Rough idle and power loss, Eventually catastrophic rod knock and engine seizure

Fix: The M275 suffers from undersized main and rod bearings combined with crankshaft flex under boost. Fix requires engine removal, complete disassembly, crankshaft machining or replacement, all new bearings, typically pistons and rings while you're in there. 60-80 hours labor for full rebuild, 40-50 for short block swap if you source a good used unit.

Estimated cost: $15,000-30,000

Typical onset: 80,000-120,000 mi

Symptoms: Blue smoke on startup or acceleration, Screaming or grinding noise under boost, Sudden loss of power, Check engine light with underboost codes, Oil consumption increase

Fix: Turbos fail from oil starvation (often related to the bearing problems) or shaft wear. Requires removing engine undertray, exhaust components, and turbo assemblies. 12-16 hours per side, always do both if one fails. Must address root cause oil pressure issues or new turbos will fail quickly.

Estimated cost: $8,000-14,000

Typical onset: 70,000-110,000 mi

Symptoms: Harsh or delayed shifts, Transmission slipping between gears, Limp mode activation, Transmission overheating warnings, Fluid leaks from bell housing area or cooler lines

Fix: The 722.9 seven-speed has issues with internal oil cooler and valve body conductor plate. Cooler lines crack, conductor plate wiring harness fails. Requires transmission removal for proper repair. 18-24 hours labor including fluid flush and adaptations.

Estimated cost: $4,500-7,500

Typical onset: 80,000-130,000 mi

Symptoms: Suspension warning light, Car sitting low on one corner, Hydraulic fluid puddles under car, Rough ride quality, ABC inactive message, Whining noise from pump

Fix: ABC struts, accumulators, and hydraulic lines develop leaks. Strut replacement is 3-5 hours per corner. Pump replacement is 6-8 hours. Lines vary. System uses expensive MB-specific fluid. Must pressure test to find all leaks as one repair often reveals another.

Estimated cost: $2,500-8,000

Typical onset: 90,000-140,000 mi

Symptoms: Compressor runs constantly, Car sagging overnight or when parked, Suspension warning light, Inability to raise or lower suspension, Compressor overheating and shutting down

Fix: If equipped with Airmatic instead of ABC, compressor and valve block fail from overwork due to strut leaks. Struts 3-4 hours each, compressor 4-6 hours. Always inspect all four struts when one fails. Relay and valve block issues add diagnostic time.

Estimated cost: $2,000-5,000

Typical onset: 100,000-150,000 mi

Symptoms: Extended cranking before start, Rough running and misfires, Fuel smell in cabin or engine bay, Check engine light with fuel trim codes, Loss of power under load

Fix: Direct injection system runs extremely high pressure. Pump fails, injectors leak or clog. Pump is 6-8 hours in the valley of the V12. Injectors are 10-14 hours for all twelve due to access. Fuel filters also commonly neglected on this chassis.

Estimated cost: $3,500-9,000

Typical onset: 60,000-100,000 mi

Symptoms: Clunk when shifting into drive or reverse, Vibration at idle in drive, Excessive engine movement visible when accelerating, Transmission thunk during shifts

Fix: Hydraulic mounts fail from age and the V12's weight. Engine mounts are 4-6 hours, transmission mount is 3-4 hours. Critical to replace before they damage other components. Relatively cheap compared to other S600 issues.

Estimated cost: $1,200-2,500