Mercedes Workshop Manual Om646 Engine -

The OM646 succeeded the OM611 engine. It brought major improvements in emissions, noise reduction, and power delivery. The engine features a cast-iron block and an aluminum cylinder head with dual overhead camshafts (DOHC) and 4 valves per cylinder. Engine Profiles

While reliable, the OM646 has known weak points that a good manual will teach you how to prevent or fix.

| Mercedes Model | Years of Production | Engine Designation | Peak Power Output | | :--- | :--- | :--- | :--- | | C-Class (W203) | 2003 – 2007 | OM646 DE22 LA | 122 – 150 hp | | C-Class (W204) | 2007 – 2009 | OM646 DE22 LA EVO | 136 – 170 hp | | E-Class (W211) | 2002 – 2009 | OM646 DE22 LA / EVO | 122 – 170 hp | | Vito / Viano (W639) | 2003 – 2010 | OM646 DE22 LA red. | 87 – 150 hp | | Sprinter (W906) | 2006 – 2009 | OM646 DE22 LA / EVO | 95 – 150 hp |

, replacing oil filter elements, and measuring cylinder bores. Component Overhaul: Guides for the fuel system Mercedes Workshop Manual Om646 Engine

Perhaps the most valuable feature for the professional technician is the strict requirement for Special Tools. The manual does not allow for "make-do" repairs; it lists every required tool by part number:

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This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. The OM646 succeeded the OM611 engine

A professional workshop manual for the OM646 typically includes:

| Component | Torque (Nm) | Notes | |-----------|-------------|-------| | Cylinder head bolts (M12) | 40 Nm + 90° + 90° | Always replace bolts, use ARP assembly lube | | Main bearing cap bolts | 50 Nm + 90° | | | Connecting rod bolts | 20 Nm + 90° | Replace after each use | | Camshaft bearing caps | 10 Nm | Sequence from center outward | | Crankshaft pulley bolt (center) | 200 Nm + 90° | Use locking tool; do not impact | | Injector clamp bolt | 7 Nm + 90° | Critical; over-torquing cracks injector body | | Glow plug | 15 Nm | Apply anti-seize | | Oil filter housing (to block) | 25 Nm | Replace O-rings | | Timing chain tensioner | 40 Nm | |

The OM646 introduced significant advancements in fuel injection. The workshop manual demystifies this complex system:

Mercedes relies heavily on external and internal Torx fasteners across the entire engine block.

Soften the carbon crust using specialized solvent. Remove the injector hold-down bolt carefully to avoid snapping it in the cylinder head.