Mercedes Benz Sl Problems & Known Issues

Flexible brake hoses on SL models deteriorate at 24.3 times the national fleet average, with failures documented across all mileage ranges from 20,000 miles upward. The flexible sections connecting the brake calipers to the rigid brake lines are subject to heat cycling from the brakes and movement from suspension travel. Age-related rubber degradation causes internal delamination and external cracking, potentially leading to brake fluid loss and brake failure. This is classified as dangerous due to the direct safety implications.

This typically manifests as corrosion to the rear subframe mounting points, front suspension mounting areas, and sill structures that support the convertible top mechanism. The aluminium-steel construction creates galvanic corrosion issues where dissimilar metals meet. Once structural rigidity is compromised, the convertible body experiences increased flex which accelerates further deterioration and affects occupant safety in a collision.

The recirculating ball steering box on R129 5.0-litre models develops internal seal failure, allowing power steering fluid to leak from the box housing onto the road surface. The steering box is a sealed unit requiring complete replacement rather than rebuild, making this an expensive repair. Later R230 models use rack-and-pinion steering which is not subject to this specific failure mode.

The rubber dust covers protecting ball joints and suspension bushes deteriorate rapidly on SL models, failing at 52 times the national fleet average according to MOT data. Once the protective cover splits, dirt and moisture enter the joint causing accelerated wear and eventual failure. This affects multiple suspension components simultaneously across front and rear suspension systems. The combination of age-related rubber degradation and the convertible body structure's increased chassis flex accelerates this deterioration.