2006 — 2012
5.5L V8 (M273) - GL 500/GL 550
Petrol
Test drive task: Find a quiet road and engage the Airmatic suspension's lift mode. | Detail: In cars of this age, it's common to consider how the compressor performs. Listen for excessive noise or a struggle to level the vehicle, as the air struts and pump are components that often require attention as they reach higher maturity.
Test drive task: During a cold start, pop the hood and listen closely to the engine rhythm. | Detail: It is worth noting that the M273 V8 engine can sometimes exhibit timing chain tensioner wear. A gentle rattle that fades as the engine warms is a sign that you might want to look into its service history for previous chain-related maintenance.
Check this by: Operating all electronic functions, including the seat adjustments and the third-row folding mechanism. | Detail: The GL-Class has a vast amount of cabin tech; occasionally, sensor modules or wiring harnesses in the doors can become temperamental, so verifying every button is a great way to gauge the vehicle's electrical health.
Check this by: Inspecting the coolant reservoir and checking for any signs of oil contamination. | Detail: In older M273 units, it is wise to keep an eye on the oil cooler seals. If you notice any unusual residues, it is helpful to verify when the gaskets were last serviced, as proactive maintenance here prevents more complex cooling system issues.
Consider a comprehensive transmission service, as the 7G-Tronic gearbox benefits greatly from fresh fluid at this stage.
This is often the time when engine mounts and transmission mounts start to show their age, impacting cabin refinement.
A good point to audit the entire cooling system, including the radiator and hoses, to ensure long-term reliability.
Prioritise regular oil changes every 7,500km to keep that M273 engine internals happy.
Keep the panoramic sunroof drains clear to prevent moisture build-up in the footwells.
Ensure the transmission fluid and filter are replaced on schedule to protect the 7-speed gearbox.
Check the condition of the control arm bushings; replacing these significantly improves the 'Mercedes feel' on NZ roads.
Verify the brake fluid level and moisture content, as this is often overlooked but crucial for safety.
Estimated repair costs if issues arise
If the suspension components show signs of sagging after parking, you might eventually need to budget for strut or compressor refurbishment. It is a significant job, but it restores the vehicle's signature ride quality.
Depending on the car's history, you might eventually need to budget for a timing chain update if the engine develops a distinct start-up noise. Addressing this proactively helps maintain the longevity of the M273 powerplant.
If this component needs attention in the future, the estimated cost in NZ involves labour to access the deep valley of the engine. It is a common task for high-mileage examples that keeps the engine bay clean and prevents leaks.
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Disclaimer: This report is generated with the assistance of AI analysis based on verified automotive data. While we strive for 100% accuracy, enthusiasts should always conduct physical inspections and consult service records. View Full Disclaimer