Volvo Penta D2-50 Bobtail Inboard Marine Diesel Engine

Description

Dense ASTM gray cast iron casting ensures superior vibration damping and structural longevity in the Volvo Penta D2-50 Bobtail Marine Engine. This 4-Cylinder 2.2L mechanical diesel generates 47.0BHP continuous power at 2,800 RPM for displacement cruisers. Operators must complete overhead valve lash adjustments every 500 operating hours and inspect raw water heat exchanger zincs on seasonal schedules.

Structural casting uses an ASTM gray iron monobloc block featuring parent cylinder bores and an overhead-valve cylinder head. The 12V negative ground electrical plant carries a 2.0 kW starter motor and a 115A marine alternator equipped with remote battery sensing. Dry engine weight measures 496 lbs without transmission. The engine mounting stance occupies 27.7in of length, 21.4in of width, and 24.0in of height, serviced by a 1.72 US gal lube oil pan.

Key Features of Volvo Penta D2-50

Cruising sailboat skippers buy Volvo Penta D2-50 bobtail marine engines to secure dependable auxiliary thrust in displacement hulls up to 43ft. The bare bobtail design aids sailing yacht auxiliary engine repower projects through compatibility with multiple mechanical and hydraulic transmissions.

• Cam-driven in-line injection pumps provide individual cylinder metering for smooth low-RPM operation.
• Naturally aspirated 4-Cylinder configuration produces balanced torque output with minimal secondary engine vibration.
• Sound-attenuated air intake silencer suppresses induction pulses to keep cabin quarters quiet under power.
• Tubular heat exchanger maintains closed-circuit engine coolant temperature in harsh saltwater environments.
• High-capacity 115A marine alternator restores auxiliary battery banks during short harbor motoring runs.
• Dedicated bellhousing mounts flexible marine dampers compatible with MS25A, HS25A, and ZF transmissions.
• Neoprene impeller seawater pump circulates cooling water into the water-injected exhaust mixer elbow.

Dynamometer Performance Bench Test Data

Dynamometer load verification proves 47.0BHP continuous power and 92 ft-lbs of shaft torque at 2,800 RPM, peaking at 51.0BHP at 3,000 RPM. Exhaust pyrometer temperatures hold under 930°F upstream of the water-injected exhaust elbow. The closed-circuit freshwater loop stabilizes at 180°F through the tubular heat exchanger under continuous full-load testing. Main bearing oil pressure registers 52 PSI at cruising RPM, while crankshaft journal concentricity checks confirm runout below 0.0004in TIR across all five main bearing journals.

Field Operation Controls Installation Boundaries

Mechanical control cables require 4 lbs of linear force to advance the internal fuel rack across the governor band. This compact four-cylinder diesel is not designed for fast planing hulls, commercial harbor tugs, or vessels lacking raw water strainers. Never select this sailing yacht auxiliary engine repower for displacement hulls exceeding 43ft or craft unable to maintain adequate engine compartment ventilation.

• Change engine oil and replace the spin-on lube filter every 150 operating hours.
• Inspect the raw water rubber impeller and replace zinc anodes every 12 months.
• Check mechanical overhead valve lash clearances to 0.008in cold every 500 operating hours.

Factory Warranty Marine Crate Manifest

Volvo Penta protects this engine with a 2-Year limited warranty plus additional 3-Year major component coverage. The factory shipping crate contains the bobtail diesel engine, 12V 2.0 kW starter, 115A alternator, four flexible engine mounts, wiring harness, basic instrument display panel, oil pressure switch, and operator maintenance manuals.