Mercedes-Benz C-Class 200 CDI Engine Replacement Compare Prices & Get Quotes

A replacement engine for a C200 CDI typically costs between £600 and £4,800 depending on the engine code and condition. Used OM646 units start from £600-£1,400, reconditioned from £1,800-£3,000, and fully rebuilt OM651 engines from £2,800-£4,800. A replacement OM651.913 engine costs on average £2,797 in good condition, with reconditioned units costing up to £3,295. Labour for supply & fit adds £500-£1,000.

• Used OM646.811 (W204 C200 CDI, 2007-2009): £600-£1,400
• Rebuilt OM646.811: £2,200-£3,800
• Rebuilt OM651.913 (W204 BlueEFFICIENCY, 2011-2014): £2,800-£4,800

"Black Death" refers to injector seal failure that affects OM646 engines. The copper washer seal between the injector and cylinder head degrades, allowing combustion gases to escape. This creates hard, black carbon deposits around the injector. Symptoms include a ticking or chuffing noise, a strong diesel smell in the cabin, hissing sounds from the engine, and visible black tar-like residue. If left untreated, the injector can seize in the cylinder head, requiring expensive extraction and head repairs.

• Affects OM646.811 and OM646.812 engines in W204 C200 CDI
• Early repair (£180-£300 per injector) prevents injector seizure
• Ignoring it can lead to £1,200+ head repair costs

It depends on the engine. The OM646 (W204 C200 CDI, 2007-2009) uses a duplex timing chain at the front of the engine, which is robust and does not require scheduled replacement. The OM651 (W204 C200 CDI BlueEFFICIENCY, 2011-2014) uses a timing chain at the rear of the engine, which is prone to stretching. A metallic rattling noise on cold start is the classic warning sign.

• OM646: front-mounted duplex timing chain - durable, no scheduled replacement
• OM651: rear-mounted timing chain - prone to stretch at 80k-120k miles
• Rattling on cold start is the warning sign for OM651

It depends on the generation and condition. A W204 C200 CDI is typically worth £2,500-£6,000 - a rebuilt OM646 or OM651 engine (£2,200-£4,800) can be a worthwhile investment if the car is in good condition. For vehicles with lower values, a used engine or targeted repair (injector seals, timing chain) is often more economical. Always compare the cost of repair against the car's market value.

• W204 (2007-2014): rebuilt engine with warranty is viable for good condition cars
• Vehicle worth over £3,500: replacement usually justifies the cost
• Injector seal repair or timing chain replacement: often more economical than full replacement

The OM646 is a 2.2-litre diesel used in the W204 C200 CDI (2007-2009) with a front-mounted duplex timing chain and piezo injectors. The OM651 is a 2.1-litre diesel introduced in the W204 C200 CDI BlueEFFICIENCY (2011-2014), featuring a rear-mounted timing chain and 2,000 bar rail pressure. Both produce 136 hp, but the OM651 offers increased torque (360 Nm vs 270 Nm).

• OM646: 2.2L, 136 hp, front timing chain, W204 (2007-2009)
• OM651: 2.1L, 136 hp, rear timing chain, W204 BlueEFFICIENCY (2011-2014)

Power loss in the C200 CDI is most commonly caused by EGR valve clogging, turbocharger issues (sticking variable vanes), or injector seal failure ("Black Death"). On OM651 engines, timing chain stretch can also cause cam timing drift and power loss. A diagnostic check with Mercedes STAR or compatible equipment is essential to identify the exact cause.

• EGR valve clogging - carbon deposits from short journeys
• Turbocharger vanes - sticking from carbon buildup
• Injector seals - "Black Death" causing compression loss
• Timing chain stretch (OM651) - power loss + rattling