2005 — 2007
2.7L I5 (OM647)
Diesel
Check transmission conductor plate | Note: Look for harsh shifting or 'limp mode'; the 722.6 transmission is prone to electrical faults caused by fluid wicking into the TCU.
Cold start rattle | Note: Listen for excessive chain noise or injector tick; the OM647 is reliable but neglected oil changes kill the chain tensioners.
Inspect coolant expansion tank | Note: Check for oil contamination. The oil cooler seals are a known weak point and can lead to internal oil/coolant mixing.
Test all electronic modules | Note: Cycle through seat adjustments, central locking, and infotainment; water ingress into the SAM (Signal Acquisition Module) is a common W203 headache.
Usually indicates the end of a long-life oil interval; if not verified, perform an immediate flush and filter change to prevent sludge.
Transmission fluid and filter replacement is critical here, despite 'sealed for life' claims by Mercedes-Benz.
Expect to replace glow plugs, glow plug relay, and inspect the turbo actuator for carbon buildup.
Full synthetic oil change (5W-30/5W-40) every 10,000km maximum
Replace transmission conductor plate and fluid at first sign of solenoid lag
Clean EGR valve and intake manifold to prevent power loss from soot buildup
Inspect suspension control arm bushings for splitting (common NZ road wear)
Flush coolant system and replace thermostat to maintain optimal operating temp
Estimated repair costs if issues arise
Essential for reliable starting during cold NZ winters.
High priority, failure will leave you stranded.
Watch for loss of power on steep inclines.
NZ roads require solid bushes; budget for control arms and links.
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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