2007 MERCEDES-BENZ S63 AMG

Typical onset: 60,000-100,000 mi

Symptoms: coolant loss with no visible external leaks, white smoke from exhaust on cold start, rough idle and misfires, coolant in oil or oil in coolant in severe cases

Fix: The M156 uses single-use head bolts that stretch over time and lose clamping force, causing head gasket failure. Requires both cylinder heads removed, new head gaskets, ARP head studs (highly recommended over OE bolts), machine work if heads are warped, and complete timing chain service while apart. 30-40 hours labor minimum.

Estimated cost: $8,000-12,000

Typical onset: 50,000-80,000 mi

Symptoms: metallic ticking or tapping from valve train that worsens when warm, check engine light with camshaft position codes, metal shavings in oil, loss of power

Fix: Early M156 engines had inadequate cam hardening and aggressive lifter profiles that caused premature wear. Requires both cylinder heads off, all camshafts replaced (intake and exhaust, both banks), all lifters, and often valve damage repair. Updated parts are available. 35-45 hours labor.

Estimated cost: $10,000-15,000

Typical onset: 80,000-120,000 mi

Symptoms: deep knocking noise from lower engine, metal shavings in oil filter, loss of oil pressure, catastrophic engine failure if continued

Fix: The M156 balance shaft bearings can fail due to oil starvation or debris from other failures, and main bearings can spin if oil changes are neglected. Engine must come out for either issue—full teardown, machine work on block, new bearings, balance shaft module, and reassembly. Many owners opt for short block replacement or reman engine at this point. 50-70 hours labor.

Estimated cost: $15,000-25,000

Typical onset: 70,000-110,000 mi

Symptoms: transmission fluid leaking from front of engine area, transmission overheating warnings, harsh or delayed shifts when fluid is low

Fix: The external transmission oil cooler lines and cooler itself develop leaks from age and heat cycles. Requires radiator support removal for access, new cooler, lines, and transmission fluid flush. 6-8 hours labor.

Estimated cost: $1,500-2,500

Typical onset: 60,000-90,000 mi

Symptoms: clunk when shifting from park to drive or reverse, vibration through chassis during acceleration, visible sagging of transmission tail

Fix: The rear transmission mount collapses from the weight and torque of the 722.9 transmission. Straightforward replacement but requires transmission support and exhaust work for access. 3-4 hours labor.

Estimated cost: $600-1,000

Typical onset: 80,000-120,000 mi

Symptoms: vehicle sagging at one or more corners overnight, compressor running constantly, ride height warnings on dash, harsh ride quality

Fix: Airmatic struts develop leaks in the air bladders, and the compressor burns out from overwork. Individual strut replacement is 2-3 hours each, compressor is 4-5 hours. Many owners convert to coilovers to eliminate future issues but lose adaptive damping.

Estimated cost: $1,200-2,000 per strut, $2,000-3,000 compressor

Typical onset: 70,000-100,000 mi

Symptoms: ABC warning light and vehicle drops to ground, hydraulic fluid leaks under vehicle, harsh ride and poor body control, car will not drive when system fails

Fix: The hydraulic ABC system has pulsation dampers that fail internally, pump failures, and line leaks. Diagnosis is critical—could be a $500 damper or a $5,000 pump. System requires specialized diagnostic tools. Labor varies wildly, 4-20 hours depending on component.

Estimated cost: $2,000-8,000