Volvo Penta MD17C Specifications
| Engine Model: Volvo Penta MD17C |
| Engine Type: 4-cycle inline 3-cylinder naturally aspirated freshwater-cooled diesel |
| Total Displacement: 102 cu.in (1.68 L) |
| Rated Engine Power: 35 Hp (26 kW) at 2500 rpm |
| Fuel System Type: Direct injection |
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The Volvo Penta MD17C is a three-cylinder,
naturally aspirated marine diesel engine produced by Volvo Penta from
the late 1970s through the early 1980s. This powerplant was engineered
as the larger displacement sibling to the MD11 and MD16 series, designed
specifically for heavy displacement sailing yachts and displacement
motor cruisers where low-revving, high-torque performance was required.
The MD17C gained recognition for its robust cast iron construction,
individual cylinder heads, and fuel-efficient direct injection system.
The engine’s architecture reflects Volvo Penta’s conservative marine
engineering philosophy, prioritizing reliability and
field-serviceability over power density. The cast iron cylinder block
with individual cylinder heads permits maintenance on a single cylinder
without disturbing the others - a valuable feature for sailors in remote
locations. The naturally aspirated configuration delivers 26 kW (35 hp)
at 2,500 rpm, with peak torque available at lower engine speeds suited
to propeller curves.
The MD17C was offered with either MSB or MS2 reverse gear mechanical
transmissions or 110S/120S saildrive units, accommodating various hull
configurations. This engine became a popular choice for cruising yachts
between 10 m (33 ft) and 12 m (40 ft), including Hallberg-Rassy, Najad,
and Vindo models.
The MD17C is a four-stroke, water-cooled, naturally aspirated marine
diesel engine configured for inboard installation with either a shaft
drive or saildrive transmission. The engine utilizes direct injection
with a mechanical governor.
Engine Type: Inline-3, 4-cycle, water-cooled, naturally aspirated marine
diesel
Displacement: 1.68 L (1,680 cc / 102 cu.in)
Bore: 88.9 mm (3.50 in)
Stroke: 90.0 mm (3.54 in)
Compression Ratio: 17.0:1
Firing Order: 1-2-3
Valvetrain: OHV (Overhead Valve), 6-valve (2 valves per cylinder)
Crankshaft Power: 26 kW (35 hp) at 2,500 rpm
Propeller Shaft Power: 25 kW (34 hp)
Rated Speed: 2,500 rpm
Low Idle Speed: 600 rpm
Maximum No-Load Speed: 2,750 rpm
Injection Timing: 20° before top dead center
Injection Pressure: 14.0-15.0 MPa (2,030-2,180 psi)
The cylinder block is manufactured from cast iron using a high-pressure
die-casting process, selected for its dimensional stability, wear
resistance, and ability to withstand the sustained loads of marine
diesel operation. The block features a deep-skirt design extending below
the crankshaft centerline, providing a rigid foundation for the rotating
assembly.
The cylinder bores are machined directly into the iron casting with a
plateau-honed finish optimized for cast iron piston ring packs. The
block incorporates a siamesed bore configuration where adjacent
cylinders share common walls, reducing overall engine length and
increasing structural rigidity. Water jackets surround each cylinder
bore, with coolant flow directed from the seawater or fresh water pump
into the block before rising into the cylinder heads.
The crankcase incorporates four main bearing supports with the bearing
webs integrated into the block casting. Main bearing caps are
manufactured from cast iron and secured with two bolts per cap. The
block includes mounting provisions for the Bosch inline injection pump,
gear-driven from the crankshaft, and the oil cooler. A cast aluminum oil
pan is bolted to the lower crankcase flange.
Block Material: Cast iron
Bore Diameter: 88.9 mm (3.50 in)
Cylinder Configuration: Inline, siamesed bores
Main Bearing Quantity: 4
Main Bearing Cap Design: Cast iron, two-bolt attachment
Balance Shafts: Not equipped
The MD17C features a distinctive individual cylinder head design. Three
separate cylinder heads - one per cylinder - are mounted on the cylinder
block. Each head covers one cylinder and incorporates two valves (one
intake, one exhaust). This configuration permits removal and servicing
of a single cylinder head without disturbing the other cylinders.
Each cylinder head is constructed from cast iron using a permanent mold
casting process, selected for thermal stability and compatibility with
the cast iron cylinder block in marine installations. The cross-flow
port configuration places intake ports on one side and exhaust ports on
the opposite side. The OHV valvetrain operates six valves - two per
cylinder - via pushrods and rocker arms.
The camshaft is located within the cylinder block and driven by a gear
train from the crankshaft. Camshaft lobes actuate mechanical lifters
(tappets) that translate motion upward through pushrods to the rocker
arms mounted on a rocker shaft. Valve clearance adjustment is performed
manually using a screw-and-locknut adjuster at the rocker arm. The
combustion chambers are of a direct injection design with a centrally
located bowl machined into the piston crown.
Each cylinder head incorporates pressed-in valve seat inserts, with
exhaust seats manufactured from a heat-resistant nickel-based alloy.
Valve guides are pressed into each head.
Head Material: Cast iron (individual heads per cylinder)
Valve Configuration: OHV, 6-valve (2 valves per cylinder)
Intake Valve Diameter: 42.0 mm (1.65 in)
Exhaust Valve Diameter: 38.0 mm (1.50 in)
Valve Stem Diameter: 9.0 mm (0.35 in)
Valve Seat Angle: 45 degrees
Camshaft Drive: Gear train from crankshaft
Valve Clearance (Cold, Intake): 0.30-0.40 mm (0.012-0.016 in)
Valve Clearance (Cold, Exhaust): 0.30-0.40 mm (0.012-0.016 in)
Interference Engine: No - valve-to-piston clearance maintained
The fuel system is a mechanically controlled direct injection design
utilizing an inline injection pump. The pump - a Bosch inline jerk-type
pump - is mounted on the side of the cylinder block and driven by a gear
train from the crankshaft. A mechanical governor integrated into the
pump housing controls fuel delivery based on engine speed and load.
The mechanical governor provides stable idling and governed maximum
speed control. A manual shut-off lever or electric shut-off solenoid
stops the engine by cutting fuel supply to the injection pump. A
mechanical lift pump mounted on the cylinder block draws fuel from the
marine fuel tank through a primary water-separating filter and delivers
it to the injection pump. A secondary spin-on fuel filter is mounted
between the lift pump and injection pump.
The injectors are of the pintle or multi-hole nozzle type, calibrated to
open at pressures between 14,000 kPa and 15,000 kPa (2,030-2,180 psi).
Each injector is retained in the cylinder head by a clamp and sealed
with a copper washer. Excess fuel from the injector leak-off passages
returns to the fuel tank.
Injection Type: Direct injection, mechanical inline jerk pump
Injection Pump Type: Bosch inline 3-cylinder, mechanical governor
Injector Opening Pressure: 14.0-15.0 MPa (2,030-2,180 psi)
Injection Timing: 20° BTDC
Fuel Filtration: Primary water-separating filter plus secondary spin-on
filter
Governor: Mechanical, variable-speed
Fuel Requirement: Diesel fuel meeting EN 590 or ASTM D975; minimum
cetane 45
The lubrication system is a fully pressurized, wet-sump design with a
gear-type oil pump mounted internally within the timing gear case and
driven by the camshaft gear. The oil pump utilizes a pair of meshing
gears to generate flow with positive displacement characteristics.
Oil is drawn from the cast aluminum oil pan through a mesh strainer
positioned at the sump’s lowest point. Pressurized oil passes through a
full-flow, replaceable oil filter mounted externally on the cylinder
block. The filter is of the spin-on type and incorporates a bypass valve
that permits oil flow to continue if the filter element becomes
restricted. From the filter, oil enters the main oil gallery cast
longitudinally through the cylinder block, supplying the crankshaft main
bearings, connecting rod bearings, camshaft bearings, rocker arm
assemblies, and injection pump drive gear.
A pressure relief valve bypasses excess oil flow back to the oil pan
when system pressure exceeds the calibrated limit. An oil pressure gauge
sender or pressure switch provides indication to the helm instrument
panel. The lubrication system includes an oil cooler - a water-to-oil
heat exchanger - to maintain lubricant temperature under sustained
marine operation.
Oil Type: Diesel engine oil meeting API CC, CD, or CE; SAE 15W-40 or
20W-50 viscosity
Oil Capacity (with filter): 4.4 L (4.6 US qt)
Oil Pressure (at idle, warm): 70-140 kPa (10-20 psi)
Oil Pressure (at rated speed): 280-420 kPa (41-61 psi)
Oil Pump Type: Gear-type, camshaft-driven
Oil Cooler: Water-to-oil heat exchanger
The cooling system on original MD17C engines was seawater-cooled (direct
cooling). Seawater is drawn through a seacock and strainer, circulated
by a flexible impeller pump through the engine block and cylinder head,
then discharged overboard. Many engines have been converted to fresh
water cooling (indirect cooling) using aftermarket heat exchanger kits
such as those from Martec. The following data describes the original
seawater-cooled configuration.
A flexible impeller-type raw water pump (rubber impeller) is mounted on
the front of the engine and driven by the camshaft belt or gear. This
pump draws seawater and circulates it through the engine block water
jackets, cylinder head passages, and exhaust manifold before discharging
overboard.
A wax-pellet thermostat mounted in a housing on the cylinder head outlet
regulates seawater flow. The thermostat begins opening at a calibrated
temperature and achieves full opening within a defined temperature
range. A bypass circuit permits seawater circulation within the engine
during warm-up. The seawater-cooled system does not use a radiator or
heat exchanger; seawater passes directly through the engine block.
Fresh water conversion kits replace the direct seawater circulation with
a closed coolant loop. A centrifugal fresh water pump circulates
antifreeze through the engine block and heat exchanger. Seawater flows
through the heat exchanger tubes, removing heat from the fresh water
coolant.
Coolant Type (Original): Seawater (no antifreeze in engine block)
Coolant Type (Converted): Ethylene-glycol based antifreeze in closed
circuit
Thermostat Opening Temperature: 70-80 °C (158-176 °F)
Raw Water Pump Type: Flexible impeller (rubber), camshaft-driven
Raw Water Pump Impeller: Service life 200-500 hours; inspect annually
Heat Exchanger (Converted): Shell-and-tube or plate type
| Intake and Exhaust Systems |
Intake System: The intake system incorporates a flame arrester mounted
on the intake manifold, replacing a dry paper air cleaner in marine
installations. The flame arrester prevents engine backfire from igniting
flammable vapors in the engine compartment. The intake manifold is a
cast aluminum or cast iron design.
Exhaust System: The exhaust manifold is a cast iron single-piece design
collecting exhaust gases from all three cylinders. A water-cooled
exhaust elbow injects raw cooling water into the exhaust stream, cooling
the exhaust gases before they exit through the vessel's exhaust system
(wet exhaust). A waterlock or gooseneck arrangement prevents seawater
from flowing back into the engine.
Governor: The mechanical governor is integrated into the injection pump
and provides droop characteristics suited to marine propeller loads. A
remote throttle cable connects to the governor control lever at the
injection pump.
Starting System: The engine is equipped with a 12-volt electric starting
system. A gear-reduction starter motor engages with the flywheel ring
gear. Glow plugs (one per cylinder) provide cold-start assistance. A
preheat switch on the instrument panel activates the glow plugs for
10-20 seconds before starting.
Reverse Gear / Transmission: The MD17C was offered with mechanical
reverse gear transmissions (MSB or MS2) providing forward, neutral, and
reverse with reduction ratios of 1.91:1, 2.39:1, or 2.76:1. The
transmission is mounted directly to the engine flywheel housing.
Saildrive Option: The 110S or 120S saildrive unit replaces the reverse
gear, providing a vertical output shaft passing through the hull. The
saildrive includes its own oil sump and propeller shaft.
Timing Drive: The camshaft and injection pump are driven by a gear train
from the crankshaft. A crankshaft gear drives an idler gear, which
drives the camshaft gear and the injection pump drive gear. This
gear-driven system requires no periodic replacement.
Overall Length: 950 mm (37.4 in)
Overall Width: 520 mm (20.5 in)
Overall Height: 740 mm (29.1 in)
Dry Weight (with MSB gearbox): 290 kg (639 lb)
Dry Weight (with 110S saildrive): 310 kg (683 lb)
Engine Oil Change: 100 operating hours or annually.
Engine Oil Filter Change: At every oil change.
Fuel Filter Replacement: 200 operating hours or annually.
Raw Water Pump Impeller Inspection: 200 operating hours.
Raw Water Pump Impeller Replace: 500 hours or if cracked.
Valve Clearance Inspection: 200 operating hours; adjust as required.
Glow Plug Inspection: 500 operating hours; test resistance and function.
Injector Service: 500 operating hours inspection and calibration.
Injection Pump Timing: Inspect following any pump removal or drive gear
disturbance.
Drive Belt (Raw Water Pump) Inspection: 100 operating hours.
Cooling System Zinc Anodes: Inspect every 200 operating hours.
Transmission Oil Change (MSB/MS2): 200 operating hours or annually.
Saildrive Oil Change (110S/120S): 200 operating hours or annually.
Cylinder Head Bolts (M12 x 1.5), 1st pass: 30 Nm (22 lb-ft)
Cylinder Head Bolts (M12 x 1.5), 2nd pass: 60 Nm (44 lb-ft)
Cylinder Head Bolts (M12 x 1.5), Final pass: 100-110 Nm (74-81 lb-ft)
Main Bearing Cap Bolts (M12 x 1.5), 1st pass: 40 Nm (30 lb-ft)
Main Bearing Cap Bolts (M12 x 1.5), Final pass: 90-100 Nm (66-74 lb-ft)
Connecting Rod Cap Bolts (M10 x 1.25), 1st pass: 20 Nm (15 lb-ft)
Connecting Rod Cap Bolts (M10 x 1.25), Final pass: 50-55 Nm (37-41
lb-ft)
Rocker Arm Shaft Bolts (M10 x 1.5): 35-40 Nm (26-30 lb-ft)
Intake Manifold Bolts (M8 x 1.25): 20-25 Nm (15-18 lb-ft)
Exhaust Manifold Nuts (M8 x 1.25): 25-30 Nm (18-22 lb-ft)
Injection Pump Mounting Nuts (M8 x 1.25): 20-25 Nm (15-18 lb-ft)
Fuel Injector Holders (M24 x 1.5): 50-60 Nm (37-44 lb-ft)
High-Pressure Fuel Line Fittings: 20-25 Nm (15-18 lb-ft)
Oil Pan Bolts (M8 x 1.25): 15-20 Nm (11-15 lb-ft)
Water Pump Bolts (M8 x 1.25): 20-25 Nm (15-18 lb-ft)
Thermostat Housing Bolts (M8 x 1.25): 15-20 Nm (11-15 lb-ft)
Flywheel Bolts (M10 x 1.25): 60-70 Nm (44-52 lb-ft)
MSB Reverse Gear Mounting Bolts (M10 x 1.5): 45-50 Nm (33-37 lb-ft)
The Volvo Penta MD17C engine was deployed exclusively in marine
propulsion applications for displacement sailing yachts and motor
cruisers.
Sailing Yachts (33-40 ft / 10-12 m): The MD17C was widely installed in
heavy displacement cruising yachts of the late 1970s and early 1980s.
Common applications included the Hallberg-Rassy 35 Rasmus (a legendary
long-distance cruiser), Najad 34, Vindo 34/36 series, and various
Scandinavian designs from Albin, Comfort, and Sweden Yachts. The
engine’s 26 kW (35 hp) output provided adequate propulsion for hull
speeds of 7-8 knots. The low-revving nature suited the propeller curve
of heavy displacement hulls. Saildrive configuration (110S/120S) was
preferred for sailboats to reduce vibration and simplify shaft
alignment.
Motor Cruisers (Displacement Hulls): The MD17C was used in traditional
Scandinavian “Snipa” style launch boats and displacement motor cruisers
where fuel efficiency and reliability were prioritized over speed. These
vessels operated at 6-9 knots, matching the engine’s torque peak at
lower propeller speeds.
Workboats (Small Commercial): Small commercial vessels such as day-trip
passenger boats, fishing skiffs, and harbour pilot launches received the
MD17C as a dependable low-power option.
Conversions and Refits: Many MD17C engines have been repowered into
older vessels as replacements for worn MD11, MD16, or other small marine
diesels. The MD17C’s continued parts availability and simple mechanical
design make it a candidate for refit projects.
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