Volvo Penta D2-50 Inboard Diesel HS25A Gearbox Package

Description

Providing smooth hydraulic gear shifting and angled shaft alignment is the primary function of the Volvo Penta D2-50 HS25A Marine Engine. This 4-Cylinder 2.2L package outputs 47.0BHP continuous power at 2,800 RPM matched to an 8-degree down-angle hydraulic gearbox. Operators must check transmission hydraulic fluid levels on schedule and inspect raw water heat exchanger zincs every season.

Monobloc engine casting relies on an ASTM gray iron block with integrated 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 with battery sensor regulation. Total package dry weight measures 540 lbs including transmission. Physical chassis envelope dimensions require 34.0in length, 21.4in width, and 24.0in height, with a 1.72 US gal oil pan.

Key Features of Volvo Penta D2-50

Cruising monohull skippers buy Volvo Penta D2-50 HS25A marine engines to secure hydraulic shifting refinement and correct downward propeller shaft angles. The integrated transmission package simplifies sailing yacht auxiliary engine repower projects through matched factory components.

• HS25A hydraulic transmission provides effortless clutch engagement and an 8-degree down-angle shaft output.
• Cam-driven in-line injection pumps supply accurate fuel metering across the 850 to 3,000 RPM range.
• Naturally aspirated 4-Cylinder configuration produces balanced torque output with minimal secondary engine vibration.
• Sound-attenuated air intake silencer traps induction hiss inside small sailboat cabins.
• High-capacity 115A marine alternator charges auxiliary house battery banks during harbor motoring runs.
• Tubular heat exchanger maintains stable engine coolant temperatures in hot coastal sea water.
• Neoprene impeller seawater pump circulates cooling water into the water-injected exhaust mixer elbow.

Dynamometer Performance Bench Test Ratings

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 bearing contact surfaces.

Field Operation Controls Installation Boundaries

Mechanical control cables require 3 lbs of linear force to shift the hydraulic control valve on the HS25A transmission. This compact propulsion package 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 44ft or craft unable to maintain adequate engine compartment ventilation.

• Drain engine lube oil and replace spin-on oil filters every 150 operating hours.
• Inspect HS25A hydraulic transmission fluid level and replace zinc anodes every 12 months.
• Measure and adjust mechanical overhead valve clearances to 0.008in cold every 500 operating hours.

Factory Warranty Marine Crate Inclusions

Volvo Penta covers this complete transmission package with a 2-Year limited warranty plus additional 3-Year major component protection. The export transport crate contains the diesel engine, HS25A hydraulic gearbox, 12V 2.0 kW starter, 115A alternator, four flexible engine mounts, wiring harness, instrument display panel, and operator maintenance manuals.