1998 MERCEDES-BENZ CLK320 C208

Typical onset: 120,000-180,000 mi

Symptoms: Sudden catastrophic engine noise — loud knocking or rattling from deep in block, Metal shavings in oil, sometimes complete loss of oil pressure, Engine seizure in worst cases, Often occurs with little warning if oil changes were skipped

Fix: Balance shaft gear on crankshaft strips teeth due to wear or oil starvation, sending debris through the engine. Requires complete tear-down: short block replacement or full engine rebuild with new bearings, pistons, balance shaft assembly. 25-35 hours labor depending on scope.

Estimated cost: $5,000-9,000

Typical onset: 80,000-140,000 mi

Symptoms: Transmission fluid leaking from front of vehicle near radiator, Transmission overheating, harsh or delayed shifts, Pink or red fluid visible under car or mixed in coolant reservoir if internal cooler fails, Check engine light with trans temp codes

Fix: The 722.6 five-speed auto has cooler lines that corrode and the auxiliary cooler clogs with debris. External lines fail from rust, internal radiator cooler can fail and cross-contaminate coolant and ATF. Replace both cooler and all lines, flush system. 3-5 hours labor.

Estimated cost: $800-1,500

Typical onset: 70,000-120,000 mi

Symptoms: Heavy clunk when shifting from Park to Drive or Reverse, Vibration at idle that smooths out at higher RPM, Visible engine movement when revving in park, Excessive driveline lash on acceleration

Fix: Hydraulic engine mounts and rear transmission mount fail from age and oil leaks. Front engine mounts are especially problematic. Replace all mounts as a set for best results. 4-6 hours labor for complete mount set.

Estimated cost: $900-1,600

Typical onset: 100,000-150,000 mi

Symptoms: White smoke from exhaust, especially on cold start, Coolant loss with no visible external leaks, Bubbles in coolant reservoir or overflow when running, Rough idle, misfires, oil looks milky, Often follows an overheat event from cooling system neglect

Fix: M112 head gaskets fail if engine overheats from coolant leaks or thermostat failure. Both heads must come off, gaskets replaced, heads checked for warpage and resurfaced if needed. Address underlying cooling issue. 18-24 hours labor.

Estimated cost: $3,500-5,500

Typical onset: 60,000-130,000 mi

Symptoms: No-start condition, engine cranks but won't fire, Intermittent stalling while driving, especially when hot, Check engine light with crank/cam sensor codes, Car may restart after cooling down

Fix: Heat-related failure of crank or cam sensors causes no-start or stalling. Crank sensor is at rear of engine near flywheel (difficult access), cam sensors at front of heads. Diagnosis requires scan tool. 1.5-3 hours labor depending on which sensor.

Estimated cost: $350-650

Typical onset: null

Symptoms: Window drops into door or won't go up/down, Grinding or clicking noise from door when operating window, Window moves slowly or tilts as it travels, One-touch auto function stops working

Fix: Plastic window regulator clips and guides break with age. Very common on both doors. Requires door panel removal and regulator replacement. OE regulators are superior to aftermarket. 2-3 hours per door.

Estimated cost: $400-700