2019 MERCEDES-BENZ S600

Typical onset: 20,000-60,000 mi

Symptoms: metallic knocking or ticking from lower engine block especially at cold start, metal shavings in oil during change, sudden loss of oil pressure warning, catastrophic engine seizure in severe cases

Fix: Complete engine teardown required—connecting rod bearings and main bearings are undersized or failing prematurely due to manufacturing tolerances. Full engine-out rebuild with new bearings, thorough inspection of crank journals, block honing if scored. 60-80 labor hours for complete rebuild. Many owners opt for Mercedes reman engine due to liability concerns on used luxury vehicles.

Estimated cost: $25,000-45,000

Typical onset: 30,000-70,000 mi

Symptoms: excessive oil consumption (1 quart per 1,000 miles or more), blue smoke from exhaust on acceleration, rough idle and misfires, carbon buildup on intake valves

Fix: Piston rings losing tension or cracking, causing oil consumption and eventually scoring cylinder walls. Requires engine disassembly, cylinder wall inspection, honing or boring oversized, new pistons and rings. If walls are scored beyond spec, needs complete short block replacement. 50-70 hours labor for piston/ring replacement, 65-85 hours for short block swap.

Estimated cost: $18,000-38,000

Typical onset: 40,000-80,000 mi

Symptoms: transmission fluid pooling under vehicle center-front, low transmission fluid warnings on dash, harsh or delayed shifts when fluid level drops, pink or red fluid mixed with coolant in expansion tank (internal leak)

Fix: The 9G-Tronic transmission oil cooler develops leaks at crimp joints or internal failure allowing coolant/ATF cross-contamination. External leaks need cooler replacement (8-12 hours). Internal leaks contaminate both systems—requires cooler, full trans flush, coolant flush, and possibly torque converter replacement if contaminated. Access requires front subframe drop.

Estimated cost: $2,800-6,500

Typical onset: 50,000-90,000 mi

Symptoms: whistling or whining noise under boost, significant loss of power, blue or black smoke from exhaust, oil consumption increase, check engine light with underboost codes

Fix: V12 turbos fail from bearing wear, often accelerated by oil starvation during bearing problems elsewhere in engine. Each turbo is 18-24 hours labor due to tight V12 packaging. Both turbos typically replaced together on this platform as preventive measure. Requires full cooling system drain, exhaust manifold removal both sides.

Estimated cost: $12,000-18,000

Typical onset: 35,000-65,000 mi

Symptoms: clunking when shifting from P to D or R, vibration at idle in gear, excessive driveline movement visible during acceleration, transmission sag visible on lift

Fix: Hydraulic transmission mounts fail earlier than expected on V12 models due to additional weight and torque. Replacement is straightforward but requires transmission support and partial subframe lowering for access. 4-6 hours labor. OEM mounts mandatory—aftermarket don't handle V12 torque.

Estimated cost: $1,200-2,000

Typical onset: 45,000-85,000 mi

Symptoms: coolant seepage at head/block mating surface, slight coolant loss without visible external leaks, white residue on block sides, rare cases of coolant in oil (milky dipstick)

Fix: M279 develops head gasket weepage more than full failure—usually external seepage first. Both heads typically done together due to labor overlap. Engine-out preferred for V12 access. 45-60 hours labor. Head machining required if warpage detected, which is common. Often done in conjunction with bearing inspection if engine is already out.

Estimated cost: $15,000-22,000