Mercedes M273 Engine - Replacement Cost, Problems & Compatibility

A Mercedes M273 engine replacement typically costs between £3,800 and £6,500 for a reconditioned supply-only unit . Fitted costs generally add £910-£1,170 for independent specialist labour, and fully rebuilt units with upgraded timing components can reach £5,500-£8,500 supply-only.

• Fitted costs generally add £910-£1,170 for independent specialist labour.
• Fully rebuilt units with upgraded timing components can reach £5,500-£8,500 supply-only.

The most documented failure pattern for the M273 is early timing chain tensioner wear and balance shaft sprocket degradation, typically occurring between 50,000 and 90,000 miles. Early warning signs include a distinct metallic rattling noise on cold starts and check engine lights for camshaft correlation faults, which can lead to catastrophic valve-to-piston contact if ignored.

• Early warning signs include a distinct metallic rattling noise on cold starts and check engine lights for camshaft correlation faults.
• If ignored, the chain can jump teeth, causing catastrophic valve-to-piston contact.

The M273 is fitted to Mercedes-Benz premium models from 2006 to 2011, including the S-Class (W221), E-Class (W211/W212), ML/GL (W164/X164), and CL/SL (C216/R230). It powers badges ranging from the S 450 and E 550 to the ML 550 and GL 550, and you should always verify your exact sub-code via registration lookup before ordering parts.

• It powers badges ranging from the S 450 and E 550 to the ML 550 and GL 550.
• You should always verify your exact sub-code via registration lookup before ordering parts.

A reconditioned Mercedes M273 is strongly recommended over a used unit due to the well-documented timing chain tensioner and balance shaft sprocket failure risks. Used units carry a high probability of inheriting the same latent wear unless accompanied by stamped proof of a full chain and sprocket kit replacement, whereas a proper reconditioned M273 includes new, updated timing components and refreshed valley pan seals as standard.

• Used units carry a high probability of inheriting the same latent wear unless accompanied by stamped proof of a full chain and sprocket kit replacement.
• A proper reconditioned M273 includes new, updated timing components and refreshed valley pan seals as standard.

The M273.920 is a 4.5L variant, the M273.940 is a 4.7L variant, and the M273.950/M273.960 are 5.5L variants. They all share the same core 90-degree V8 architecture and the same timing chain vulnerability, but they differ in displacement, intake manifold design, and ECU calibration, meaning they are not direct interchange replacements without extensive modifications.

• They all share the same core 90-degree V8 architecture and the same timing chain vulnerability.
• However, they differ in displacement, intake manifold design, and ECU calibration, meaning they are not direct interchange replacements without extensive modifications.