Mercedes Benz Gl Problems & Known Issues

Steel brake lines on the X164 GL generation corrode extensively due to road salt exposure and the vehicle's ground clearance exposing lines to spray. The 4.0L diesel variants show particularly high failure rates at MOT testing, with corrosion severe enough to compromise braking safety. This affects the high-pressure steel lines running along the chassis, not the flexible rubber sections at the wheels. Later X166 models use improved corrosion protection.

The constant velocity joint boots on GL models deteriorate at a higher rate than the fleet average, particularly on 3.0L diesel variants. These rubber boots protect the CV joints from dirt and moisture while containing lubricating grease. The heavy weight of GL vehicles and large wheel travel in off-road use accelerates boot wear. Boot failure allows grease to escape and contaminants to enter, eventually destroying the expensive CV joint itself.

This typically relates to the complex diesel emissions system including EGR valve carbon build-up, DPF regeneration issues, or AdBlue system faults on later models. The heavy weight and frequent urban use of these vehicles exacerbates diesel emissions problems.

The 4.0L diesel X164 GL models show elevated rates of rear shock absorber failure, typically manifesting as oil leakage or complete loss of damping function. The heavy weight of these vehicles and the complexity of the air suspension system on higher trim levels contributes to premature shock wear. Standard steel spring models use conventional dampers while air suspension variants have more complex units integrated with air springs.