2009 MERCEDES-BENZ CLK350 C209

Typical onset: 70,000-120,000 mi

Symptoms: Rattling noise on cold start that disappears when warm, Check engine light with camshaft position codes, Sudden catastrophic engine failure with metal shavings in oil, Complete loss of power

Fix: The balance shaft sprocket gear wears and fragments, sending metal through the engine. Requires complete engine teardown or replacement. If caught early (just noise), balance shaft delete kit plus timing chain service runs 18-25 labor hours. After failure, you're looking at short block replacement or engine rebuild at 35-50 hours.

Estimated cost: $4,500-8,500 preventive; $8,000-15,000 after failure

Typical onset: 80,000-140,000 mi

Symptoms: Rattling on startup for first 3-5 seconds, Check engine light with timing correlation codes, Rough idle and misfires, Metal debris in oil filter

Fix: Timing chains stretch and guides wear through, risking jumped timing and valve-to-piston contact. Complete timing chain service includes all three chains, guides, tensioners, and cam adjusters. While you're in there, do balance shaft delete if not already done. 20-28 labor hours depending on additional damage assessment.

Estimated cost: $3,500-6,000

Typical onset: 90,000-150,000 mi

Symptoms: Harsh or delayed 2-3 shift, Limp mode with transmission fault codes, Slipping between gears, No reverse or erratic shifting pattern

Fix: The 722.6 valve body and conductor plate (13-pin version) develops internal wear and electrical faults. Requires trans pan removal, valve body R&R, and new conductor plate with updated 13-pin connector. Fluid and filter service mandatory. 8-12 labor hours.

Estimated cost: $1,800-3,200

Typical onset: 60,000-100,000 mi

Symptoms: Oil consumption increase (1 qt per 1,000 mi), Oil in intake manifold and throttle body, Rough idle and hesitation, Whistling noise from engine bay

Fix: Oil separator valve in valve cover clogs, causing positive crankcase pressure that pushes oil past seals and rings. Requires valve cover removal and full CCV system replacement including separator, lines, and PCV valve. Often combined with intake manifold cleaning. 6-8 labor hours.

Estimated cost: $1,200-2,000

Typical onset: 80,000-130,000 mi

Symptoms: Transmission fluid dripping from front of car, Low transmission fluid warnings, Burnt smell after highway driving, Pink fluid spots on driveway

Fix: External transmission oil cooler develops leaks at crimped connections or through corrosion. Accessed from underneath, requires cooler replacement and complete fluid flush. If coolant enters transmission through internal leaks (less common), trans rebuild required. External cooler only: 3-4 labor hours.

Estimated cost: $600-1,200 external cooler only

Typical onset: 70,000-120,000 mi

Symptoms: Clunk when shifting from Park to Drive, Vibration at idle in gear, Excessive engine movement visible when revving, Transmission tunnel vibration

Fix: Hydraulic engine/transmission mounts collapse internally, allowing excessive powertrain movement. Front mount is most common failure point. Requires subframe access and careful alignment during installation. 3-5 labor hours depending on access.

Estimated cost: $800-1,400