M51

1991–2000•6 cyl•Inline•Al / cast_iron

← Predecessor: M21

Successor: M57 →

• Timing chain (reliable) • Bosch VP37 mechanical injection pump • Intercooler for intake air cooling

The BMW M51 is an improved turbo diesel (1991–2000). Cast iron block, aluminium SOHC head, timing chain. 2.5 L, up to 143 hp (M51D25TÜ). Used in E36, E34, E38. Bosch VP37 injection pump with intercooler. Extremely reliable, often exceeds 400,000 km. Main issues: cooling system, injection pump. Glow plugs need periodic replacement.

TU

In 1996, the M51 received a technical update (M51D25TÜ). Key changes: - Variable nozzle turbocharger (VNT). - Bosch DDE 2.2 electronic engine management. - Increased power (up to 143 hp) and torque (285 Nm). - Reduced fuel consumption and emissions. - Strengthened pistons and connecting rods.