2001 MERCEDES-BENZ SL55 AMG

Typical onset: 60,000-100,000 mi

Symptoms: metallic knocking or ticking from engine bay, sudden loss of power, check engine light with multiple misfires, catastrophic engine failure with no warning

Fix: This is the notorious weak point of early supercharged M113K engines. Pistons crack at the skirt, leading to connecting rod failure and complete engine destruction. Fix requires full engine rebuild with upgradedpistons or short block replacement. Expect 25-35 labor hours for removal, rebuild, and reinstallation. Many owners opt for remanufactured long blocks.

Estimated cost: $12,000-18,000

Typical onset: 70,000-120,000 mi

Symptoms: transmission fluid pooling under vehicle, burnt transmission fluid smell, slipping or delayed shifts, overheating transmission

Fix: The 5-speed automatic's external oil cooler lines and cooler itself corrode and leak. If not caught early, low fluid destroys the transmission. Cooler replacement is straightforward but requires dropping undertray and draining system. 3-5 hours labor plus full fluid service.

Estimated cost: $800-1,500

Typical onset: 80,000-130,000 mi

Symptoms: ABC warning light illuminated, car sitting low on one corner, harsh ride or excessive body roll, hydraulic fluid leaks under vehicle, hissing noise from suspension

Fix: Active Body Control system uses high-pressure hydraulics. Struts, pump, and accumulators fail regularly. Strut replacement is 6-8 hours for a pair. Pump failure adds another 4-6 hours. ABC delete kits exist but require custom work. OE parts are obscenely expensive.

Estimated cost: $3,000-8,000

Typical onset: 60,000-100,000 mi

Symptoms: clunking when shifting from Park to Drive/Reverse, excessive vibration at idle, visible transmission sag when inspecting from below

Fix: The rear transmission mount is hydraulic-filled and deteriorates, allowing excessive drivetrain movement. Requires transmission support and 2-3 hours labor. Often done alongside other transmission work.

Estimated cost: $400-700

Typical onset: 80,000-120,000 mi

Symptoms: rough idle or stumbling under acceleration, difficulty starting when hot, intermittent stalling, loss of power at high RPM

Fix: The in-tank fuel pump and filter degrade over time, starving the supercharged engine of fuel under load. Pump access requires dropping the tank. 3-4 hours labor. Filter is inline and should be changed every 30k miles but is often neglected.

Estimated cost: $800-1,400

Typical onset: 90,000-140,000 mi

Symptoms: top operates slowly or stops mid-cycle, hydraulic fluid stains in trunk, top warning light, mechanical grinding noises during operation

Fix: Hydraulic cylinders and lines for the convertible top develop leaks. Cylinders can be rebuilt or replaced. Troubleshooting is time-consuming due to multiple actuators. 4-8 hours depending on which component failed.

Estimated cost: $1,200-2,800

Typical onset: 70,000-110,000 mi

Symptoms: high-pitched whine or grinding from front of engine, squealing on cold starts, belt shredding, loss of boost pressure

Fix: The Eaton M62 supercharger's nose drive bearing wears out. Requires supercharger removal and rebuild or replacement. Belt, tensioner, and idler pulleys should be done at same time. 8-12 hours labor.

Estimated cost: $2,500-4,500