Generations
X164 — First Generation GL-Class
2006–2012
3.0L V6 CDI
Top issues to watch for
The most serious Mercedes Benz Gl 320 problems ranked by severity. We track 5 known issues — here are the ones you need to know about first.
Dangerous
Brake pipe corrosion (X164)
The GL 320 uses steel brake pipes that are vulnerable to corrosion from road salt and moisture. The pipes run along the underside of the vehicle where they are exposed to road spray and debris. MOT data shows this model fails brake pipe corrosion checks at 3.5x the national fleet average, with failures occurring from 80,000 miles onwards. The large, heavy SUV body places high demands on the brake system, making any reduction in hydraulic pressure from corroded lines a significant safety concern.
What happens if ignoredCorroded brake pipes can fail completely under braking pressure, leading to total brake failure and potential serious accident. Even partial corrosion reduces braking efficiency and increases stopping distances. Brake pipe replacement typically requires removal of body panels and may involve welding new mounting points.
Independent garage
£400–£800
Specialist
£500–£1,000
Main dealer
£800–£1,500
Parts only
£150–£300
Dangerous
Brake hose deterioration (X164)
The flexible brake hoses on the GL 320 connect the rigid brake pipes to the brake calipers at each wheel. These rubber hoses are subject to constant flexing as the suspension moves and exposure to heat from the brake discs. MOT data shows this model fails flexible brake hose checks at 6.8x the national fleet average, typically from 100,000 miles. The failure pattern is worsening, suggesting age-related deterioration as the fleet ages.
What happens if ignoredSeverely deteriorated brake hoses can burst under pressure, causing immediate brake failure and potential serious accident. Even minor deterioration reduces braking effectiveness and can cause the brake pedal to feel spongy or require pumping. Replacement requires brake system bleeding.
Independent garage
£200–£400
Specialist
£250–£500
Main dealer
£400–£700
Parts only
£80–£150
Major
CV joint boot deterioration (X164)
The constant velocity (CV) joints at each end of the driveshafts are protected by rubber boots that contain the grease and exclude dirt and water. The GL 320's high ground clearance and off-road capability expose these boots to damage from stones and debris. MOT data shows this model fails CV joint boot checks at 3.7x the fleet average, typically from 100,000 miles. Once the boot fails, contamination destroys the CV joint rapidly.
What happens if ignoredOnce a CV joint boot fails, dirt and water contaminate the joint and wash out the protective grease. The joint will fail within a few thousand miles, causing complete loss of drive to that wheel and potential damage to the differential. Early boot replacement is much cheaper than joint replacement.
Independent garage
£150–£250
Specialist
£200–£300
Main dealer
£300–£500
Parts only
£40–£80
Major
Shock absorber deterioration (X164)
The GL 320's shock absorbers must cope with the weight of a large SUV and varying load conditions from towing or cargo. The combination of weight and the vehicle's off-road capability places high demands on the dampers. MOT data shows this model fails shock absorber checks at 2.0x the fleet average, typically around 100,000 miles. Failed dampers compromise both handling and braking performance on this heavy vehicle.
What happens if ignoredFailed shock absorbers severely compromise the vehicle's handling, braking performance, and ride quality. On a heavy SUV like the GL 320, worn dampers increase stopping distances and can cause dangerous instability during emergency maneuvers. Tyres wear unevenly and suspension components experience accelerated wear.
Independent garage
£400–£600
Specialist
£500–£800
Main dealer
£700–£1,200
Parts only
£200–£400
1 more known issues tracked
Including wear items, electrical niggles, and generation-specific problems. Check a specific car to see which issues apply to its age and mileage.
Check a specific car →MOT failure hotspots
Based on DVSA MOT test data. These are the items where the Mercedes Benz Gl 320 fails at a significantly higher rate than the average car.
Reflector defective or damaged by up to 50% of ...
Lights & Electrics · 120-150k miles
MOT failure rate: 13x the fleet average
Sample: 397 tests
Cable damaged or knotted
Brakes · 150k+ miles
MOT failure rate: 12x the fleet average
Sample: 277 tests
Seat mounting fault
Seatbelts & Airbags · 120-150k miles
MOT failure rate: 11x the fleet average
Sample: 429 tests
Brake pedal anti-slip provision missing, loose ...
Brakes · 120-150k miles
MOT failure rate: 8.7x the fleet average
Sample: 581 tests
Power steering fault
Steering · 120-150k miles
MOT failure rate: 7.0x the fleet average
Sample: 368 tests
Subframe bushes or mounts worn
Suspension · 150k+ miles
MOT failure rate: 6.9x the fleet average
Sample: 250 tests
Buying a Mercedes Benz Gl 320?
Check a specific car's service history to see if it's been looked after — franchised dealer records with dates, mileage, and work done.
Check service history£6.99 · Full refund if no records found
Related
Mercedes Benz Gl 320 reliability FAQs
What are the most common problems with the Mercedes Benz Gl 320?
The Mercedes Benz Gl 320 has 5 known issues across 3 severity levels. The most serious are: Brake pipe corrosion (X164), Brake hose deterioration (X164).
Is the Mercedes Benz Gl 320 reliable?
The Mercedes Benz Gl 320 has 2 dangerous and 2 major known issues. Most can be avoided with a thorough pre-purchase check and full service history.
How much does it cost to fix Mercedes Benz Gl 320 problems?
Repair costs range widely. The most significant issue (Brake pipe corrosion (X164)) costs £400–£800 at an independent garage. Minor issues can be under £200. Always get a full inspection before buying.