Mercedes-Benz E 300
Four-valve V6 in two basic variants: 3.5L naturally aspirated (DES 35, 185–225 kW) with direct injection and stratified charge — refined, linear, no classic naturally aspirated feel. And the 3.0L BiTurbo family (DEH 30 LA, 245–295 kW) with Nanoslide coating, twin turbochargers and water-air charge air cooler. The BiTurbo sings sonorously from 2,500 rpm and screams at the top — exceptional for a V6. Weak points: timing chain wears early when oil change intervals are pushed. Oil cooler in the V-block doesn't seal forever. Camshaft solenoids leak. On the 3.5L stratified-charge variant add NOx sensor failures from short-trip use. Early DES 35 (2011–2013) had piston slap issues. The BiTurbo unit with Nanoslide is considered more robust. Maintained with short oil change intervals (10,000–12,000 km) the engine easily lasts beyond 200,000 km.
V6 Convertible — Open Cruiser with Adequate Power
252 hp open-top: no adrenaline, but perfect for relaxed cruising. The naturally aspirated V6 sounds discreetly pleasant with the roof down — no intrusive engine note, more a gentle hum that suits open-top motoring. For sunny runs on country lanes and coastal roads just right. Those wanting more sound need the E400 or E500.
Engine Weaknesses 10
Known weak point: the oil cooler gasket in the V-block of the M276 ages and starts leaking. Repair is extremely labour-intensive because the engine must be partially disassembled — cost €1,700–3,800.
Symptoms: Oil spots under the vehicle, rainbow sheen on wet road, dropping oil level, oil smell
Known damage pattern on all newer Mercedes engines: solenoid valves leak, oil migrates into the wiring harness. First the lambda sensors die, then the ECU. Repair documented up to €1,970.
Symptoms: Check engine light with camshaft fault code, lambda sensor failure, oil film on connectors, in extreme cases ECU failure
On early M276 DES 35 (build years 2011–2013) pistons can loosen due to cylinder bore wear. Knock noise on cold start, worst case engine damage.
Symptoms: Clacking and knocking on cold start from the engine area, getting louder over time, rough idle when cold
The two-stage chain drive system of the M276 receives insufficient oil on early engines, leading to premature chain wear.
Symptoms: Rattling on cold start, rough idle, in the worst case chain jump
The M276 has a plastic thermostat housing that cracks with age and loses coolant. The thermostat itself can also fail open.
Symptoms: Coolant loss, puddle under the vehicle, fault code P0128, engine runs too cold on motorway, temperature gauge fluctuates
The M276 PCV system with oil separator is known for failures from defective membranes or blocked valves. Increased oil consumption and power loss from false air ingestion.
Symptoms: Noticeably rising oil consumption, blue smoke from exhaust, crankcase breather fault code P052E, power loss
On the M276 DES 35 (stratified-charge variant) the NOx sensors in the exhaust stream fail. Moisture accumulates at the sensor — short-trip driving prevents it from burning off. Repair costs €900–1,200 per sensor.
Symptoms: Check engine light, NOx sensor fault code, possibly increased fuel consumption and harder starting
The exhaust manifold can crack from thermal shock — especially on sportily driven examples and early build years. Welding repair is possible but not lasting.
Symptoms: Unusually loud exhaust note, power loss, exhaust smell in the engine bay or cabin, incorrect lambda sensor readings
On M276 BiTurbo variants, the wastegate linkage on the turbochargers can develop play and rattle. A progressively louder metallic noise from the turbo area. Turbocharger replacement required.
Symptoms: Metallic clattering and rattling from the engine area, especially under load, gets worse over months, boost pressure fault code
Direct injection on the M276 V6 causes carbon deposits on the intake valves. Cleaning is necessary at higher mileages.
Symptoms: Stumble when accelerating from part throttle, rough idle, slight increase in fuel consumption
Vehicle Weaknesses 14
Rear subframe rusts from the inside out. Faulty factory sealant allows water ingress. Flagged as safety-critical at MOT.
W212 steel rear subframe with powder coating cracks over time and allows moisture in. Rusts from the inside. Mercedes replaces as a goodwill gesture. Safety-critical.
Brake lines above the rear axle corrode through after 8–10 years. Brake fluid loss leads to brake failure. MOT refusal.
Rear axle corrodes through with age; suspension mounting points are flagged at MOT. Goodwill repairs possible but time-limited.
Brake lines corrode at two to twelve times the rate of comparable vehicles according to MOT data.
The rear axle is prone to severe rust-through from the inside at the weld seams of the subframe. The problem goes unnoticed for a long time. Mercedes granted goodwill replacements in some cases.
Worn joints and strut rod ends on the front axle are a recurring problem. Classic wear pattern at higher mileages.
Drain holes in the sills clog up; water collects and promotes rust from the inside.
Fabric soft-top develops cracks and leaks over the years. Moisture can damage control units.
Worn ball joints and strut top mounts on the front axle are a recurring problem. Individual owners reported multiple repairs.
The soft top tends to develop cracks in the fabric after about 10 years. Ignored cracks lead to water ingress, mould growth and control unit damage.
The drain channels in the sills clog regularly, causing water accumulation and corrosion in the sill area. Control units in the floor area can become damp.
Knocking and rattling from the front axle on uneven road surfaces. Causes: worn ball joints, anti-roll bar bushings.
The parking brake is regularly flagged at MOT. Corrosion from infrequent use causes it to seize or fail.