Mercedes-Benz E320 CDI W210

The W210 is widely regarded as one of the worst Mercedes generations for corrosion, caused by a switch to water-based paint with insufficient primer and galvanization. Some UK-market examples showed visible rust within two to three years of leaving the factory. Common areas include front wings along the bumper line, lower door edges under the window seal rubbers, boot lid seams, wheel arches, sills, and metalwork behind the headlights. Paint bubbling anywhere should be treated as a warning sign. Minor surface treatment and rustproofing starts around €500, but welding and panel replacement on heavily corroded cars can reach €3,000-4,000. Post-facelift models (1999+) are slightly better but still affected. Any W210 that has spent its life in northern or central Europe should be assumed to have some degree of corrosion unless the underside has been professionally treated and can be verified.

The front spring perches are spot-welded to the inner fender and coated in a weatherproof mastic from the factory. On many W210s, water gets behind this mastic and causes the perch to corrode from within. If a perch fails while driving, the coil spring can collapse through the arch, causing a complete loss of steering control. This is a genuine safety hazard. Mercedes acknowledged the problem and offered goodwill repairs on cars with full dealer service history (in some markets, a 30-year structural warranty covered the repair). Repair involves welding new perch plates or replacing the front subframe assembly, costing €400-800 at specialists or up to €1,500 if subframe replacement is needed. Every W210 buyer must have the spring perches inspected by lifting the car and checking from below. Any signs of flaking, distortion, or rust perforation around the perch mounts mean the car should be avoided unless you budget for immediate repair.

The OM613 common-rail injectors are sealed with copper washers at the injector seat. When these seals fail, combustion gases escape and bake into a rock-hard carbon deposit around the affected injector. Mercedes dealers informally call this black death. Early symptoms include a faint diesel smell in the cabin and a chuffing sound from the affected cylinder. If caught early, resealing involves removing the injector, cleaning the bore, and fitting a new copper washer (€300-500 for all six at a specialist). If the carbon buildup has been left too long, injectors can become seized in the head. Removal then becomes extremely difficult and can require cylinder head removal, pushing costs to €1,500-2,500. Inspect the top of the engine carefully: any black, tar-like residue around the injector bosses is a clear sign of this problem.

The 5-speed 722.6 automatic used in the W210 E320 CDI is fundamentally a reliable gearbox, but it has one well-known weak point: the conductor plate (also called the sensor plate) mounted inside the transmission pan. This plate houses the speed sensors and electrical connections. Over time, heat cycling causes micro-cracks in the circuit board, leading to intermittent no-start conditions, erratic shifting, or limp mode. The part itself costs approximately €150-250. Labor runs 3-5 hours, making total replacement cost €600-1,200 at an independent shop. Early 722.6 units (pre-2000) also had a valve body spring issue that caused 2-3 and 3-4 gear slipping. Ensure the transmission fluid has been changed at least every 60,000 km, despite some owners being told it is a sealed unit.

Like most diesel engines of this era, the OM613 suffers from EGR valve clogging due to carbon and soot accumulation. Symptoms include rough idle, hesitation under acceleration, and increased exhaust smoke. On the W210, the EGR valve is moderately accessible. Cleaning costs around €100-200 at a specialist. If the valve is too damaged for cleaning, a replacement unit costs €300-500 fitted. Regular motorway driving and avoiding extended idle periods help keep the EGR cleaner. Cars that have spent their lives doing short urban trips are far more prone to this issue.

The OM613 uses a vacuum-operated turbo wastegate actuator. Over time, the actuator diaphragm can develop leaks, vacuum hoses deteriorate, or the actuator rod seizes from carbon buildup. Symptoms include intermittent loss of power, over-boost or under-boost conditions, and occasional limp mode. The actuator itself can often be rebuilt or replaced for €200-400. If the turbo internals are damaged from oil starvation or foreign object ingestion, full turbocharger replacement runs €800-1,200 at an independent specialist. Ensuring regular oil changes with quality oil and letting the engine idle briefly before shutdown helps protect turbo longevity.

Window regulator failure is a common W210 complaint across all engine variants. The cable-and-pulley mechanisms wear and eventually snap, leaving the window stuck in place (usually down). Rear windows are more commonly affected than fronts. Parts cost approximately €60-120 per regulator, and the job takes roughly 1-2 hours per door. Some W210s never had any window regulator issues, while others needed multiple replacements. This is a nuisance rather than a safety concern, but a car with windows stuck open or unable to close fully is obviously problematic.

Individual glow plugs can fail over time, making cold starts progressively harder and causing rough running until the engine warms up. The OM613 has six glow plugs, and they are moderately accessible for replacement. Individual plugs cost €15-30 each, but if one has seized in the cylinder head, extraction can be difficult and expensive. The glow plug control relay is also a known failure point: when it fails, none of the glow plugs receive power. Relay replacement costs €150-250. A pre-purchase cold start test (engine genuinely cold, not warmed by a previous test drive) is the best way to detect glow plug issues.