Volvo Penta TAMD31 Specifications
| Engine Model: Volvo Penta TAMD31 |
| Engine Type: 4-cycle inline 4-cylinder turbocharged freshwater-cooled diesel |
| Total Displacement: 146 cu.in (2.4 L) |
| Rated Engine Power: 100-150 Hp (74-110 kW) at 3000-3900 rpm |
| Fuel System Type: Direct injection |
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The Volvo Penta TAMD31 is a 2.4-liter,
inline-4, turbocharged and aftercooled marine diesel engine. Developed
specifically for planing craft, this engine belongs to Volvo Penta‘s 31
series, produced from approximately 1985 to 2005. The TAMD31 designation
indicates a turbocharged (T) aftercooled (A) marine diesel (MD) with a
31-series displacement. The engine family includes several power
ratings: the TAMD31P (150 hp), TAMD31L (130 hp), TAMD31M (110 hp), and
TAMD31A (130 hp variant).
These engines share a common cast iron block and cylinder head
construction, featuring replaceable wet cylinder liners and oil-cooled
pistons. The aftercooler reduces intake air temperature after
turbocharging, increasing air density for more efficient combustion and
higher power output from a compact displacement. The TAMD31 gained
recognition for its compact dimensions, making it excellent for twin
installations in motorboats, sailing yachts, and commercial vessels
including lifeboats with MED (SOLAS) certification kits available.
The Volvo Penta TAMD31 occupies a respected position in the marine
diesel market as a reliable, torque-rich powerplant for vessels
requiring moderate power in a small package. The engine displaces 2.4
liters (146 cu.in), achieved through bore and stroke dimensions of 92 mm
by 90 mm. This nearly square geometry, combined with a compression ratio
of 17.5:1 on the TAMD31P and 18.0:1 on the TAMD31A, supports efficient
cold starting and complete combustion.
Power output varies by specific rating: the TAMD31P delivers 150 hp (110
kW) at 3,900 rpm (crankshaft) and 144 hp (106 kW) at the propeller
shaft. The TAMD31L produces 130 hp (96 kW) at 3,800 rpm, while the
TAMD31M offers 110 hp (81 kW) at 3,250 rpm. Peak torque on the TAMD31L
reaches 290 Nm at 1,600 rpm, demonstrating the engine‘s strong low-end
pulling power.
The fuel system employs a rotor-type injection pump with a mechanical
governor and smoke limiter. The 12-volt corrosion-protected electrical
system includes a 14V/60A alternator. The freshwater cooling system uses
a tubular heat exchanger with a separate transparent expansion tank,
allowing visual coolant level checks without opening the pressure cap.
The TAMD31 is commonly paired with Volvo Penta transmissions including
the HS45A (hydraulically shifted reverse gear with 8° down-angle), HS25A
(hydraulic drop center transmission), and MS25A/L (mechanical drop
center with straight or down-angled shafts). When maintained correctly
with regular 250-hour service intervals, these engines frequently
achieve long service lives in both recreational and commercial
applications.
Engine Type: 4-cycle, Overhead Valve (OHV), Inline-4 marine diesel
Valvetrain: OHV, 8 valves (2 per cylinder) with pushrods and rocker arms
Aspiration: Turbocharged and aftercooled
Displacement: 2.4 L (146.5 cu.in)
Bore: 92.0 mm (3.62 in)
Stroke: 90.0 mm (3.54 in)
Compression Ratio: 17.5:1 (TAMD31P)
Compression Ratio: 18.0:1 (TAMD31A and TAMD31L)
Combustion System: Direct injection
Crankshaft Power (TAMD31P): 150 hp (110 kW) @ 3,900 rpm
Propeller Shaft Power (TAMD31P): 144 hp (106 kW)
Crankshaft Power (TAMD31L): 130 hp (96 kW) @ 3,800 rpm
Propeller Shaft Power (TAMD31L): 124 hp (92 kW)
Crankshaft Power (TAMD31M): 110 hp (81 kW) @ 3,250 rpm
Propeller Shaft Power (TAMD31M): 106 hp (78 kW)
Crankshaft Power (TAMD31A): 130 hp (96 kW) @ 3,800 rpm
Crankshaft Power (TAMD31S): 100 hp (74 kW) @ 3,000 rpm (sailboat
version)
Torque (TAMD31L): 290 Nm (214 lb-ft) @ 1,600 rpm
Maximum Engine Speed (Governed): 3,250-3,900 rpm (rating dependent)
Low Idle Speed: 600-650 rpm
The cylinder block is a monobloc casting manufactured from high-strength
grey cast iron. The block incorporates replaceable wet cylinder liners,
each centrifugally cast from hardened iron. Wet liners contact the
engine coolant directly on their outer surfaces, providing superior heat
transfer from the combustion zone to the cooling system. Each liner is
sealed at the bottom with rubber O-rings to prevent coolant migration
into the crankcase.
The block design uses an open-deck configuration with integral water
jackets surrounding each liner. Five main bearing bulkheads are cast
integrally with the block, supporting a forged steel crankshaft with
induction-hardened journal surfaces. The crankcase extends below the
crankshaft centerline, forming a rigid structure that minimizes
vibration. Cast-in passages form the main oil gallery on the right side
of the block. The timing gear housing, cast into the front of the block,
contains the gear train driving the camshaft and injection pump.
The cylinder head is a single, cross-flow casting manufactured from cast
iron. The combustion chambers are of the direct-injection open type,
machined into the piston crown rather than the cylinder head. The
cylinder head carries two valves per cylinder: one intake and one
exhaust. Valves are arranged in a straight line along the head
centerline and are constructed from heat-resistant steel. The valvetrain
operates via a camshaft located in the cylinder block.
Mechanical lifters (solid tappets) follow the camshaft lobes and
transfer motion through pushrods to cast-iron rocker arms. Valve lash
adjustment uses a screw-and-locknut arrangement at the rocker
arm-to-valve stem interface. Adjustments are performed with the engine
cold. The cylinder head gasket is a composite steel-asbestos (or modern
equivalent) design. Piston cooling is managed by oil jets that spray
lubricant against the underside of each piston crown.
The fuel system is a mechanical direct-injection design. A rotor-type
(distributor) injection pump, commonly a Bosch VE type, is mounted on
the engine and driven by the timing gear train. The pump houses a single
pumping plunger and a rotating distributor rotor that directs
high-pressure fuel to each cylinder in the firing order. A mechanical
centrifugal governor, integral to the injection pump, maintains engine
speed under varying loads by adjusting fuel delivery.
A smoke limiter device on the pump reduces fuel delivery during
acceleration, minimizing exhaust smoke. A mechanical lift pump, mounted
on the cylinder block, draws fuel from the tank and delivers it through
a water-separating fuel filter to the injection pump. Each cylinder has
a multi-hole injector nozzle mounted vertically in the cylinder head.
Injectors are spring-loaded, calibrated to open at a precise pressure.
Excess fuel not injected returns to the fuel tank through a return line.
The injection pump timing is set using a dial indicator and shims.
The lubrication system is a pressurized, full-flow wet-sump design. A
gear-type oil pump is mounted on the front of the crankshaft within the
timing gear cover. The oil pump draws fluid through a screened pickup
tube from a cast aluminum or stamped steel oil pan. Oil passes through
the pump and then through a full-flow, spin-on oil filter mounted on the
cylinder block.
From the filter, pressurized oil enters the main oil gallery, a
longitudinal passage drilled through the cylinder block. The main
gallery distributes oil to all five main bearings through cross-drilled
passages. Connecting rod bearings receive oil from the main bearings via
diagonal passages drilled through the crankshaft.
A separate vertical passage carries oil to the cylinder head for
valvetrain lubrication. An integrated oil cooler, using engine coolant
flowing through a plate-type heat exchanger, maintains oil temperature
within an optimal range. Oil pressure is regulated by a spring-loaded
relief valve. A turbocharger oil feed line supplies pressurized oil to
the turbocharger center housing.
The cooling system is a sealed, pressurized, thermostatically controlled
freshwater (indirect) cooling design with a separate seawater circuit.
The freshwater circuit is closed and uses a belt-driven centrifugal
circulation pump. Coolant flows through the cylinder block water jacket,
around the wet liners, and into the cylinder head. A tubular heat
exchanger (cooler) transfers heat from the freshwater circuit to the
seawater circuit.
A transparent expansion tank, separate from the heat exchanger, allows
visual coolant level checks. The wax-pellet thermostat is rated to begin
opening at 82°C (180°F) and is fully open by 95°C (203°F). When closed,
coolant recirculates within the engine. When open, coolant flows through
the tube side of the heat exchanger. The seawater circuit uses a
rubber-impeller pump (raw water pump) that draws seawater through a hull
inlet and strainer.
Seawater passes through the shell side of the heat exchanger, absorbing
heat from the freshwater coolant, and then discharges overboard. The
aftercooler is an air-to-freshwater type: compressed air from the
turbocharger passes through a finned core while engine coolant flows
around the core. This design maintains stable intake air temperatures
regardless of seawater temperature.
| Intake and Exhaust Systems |
Intake System: Air enters through a flame-arresting air cleaner (marine
requirement) and flows through the turbocharger compressor inlet. The
compressor discharges heated compressed air into the fresh water
aftercooler. After cooling, air passes into the intake manifold, which
distributes charge air evenly to all four cylinders.
Exhaust System: A water-cooled cast-iron exhaust manifold collects
exhaust gases. The manifold is jacketed with engine coolant to maintain
low external surface temperatures. A water-cooled turbocharger turbine
housing further reduces surface temperatures. A wet exhaust elbow
injects seawater into the exhaust stream before discharge through the
hull.
Electrical System: The engine is equipped with a 12-volt,
negative-ground corrosion-protected electrical system. A 14-volt,
60-ampere alternator charges the battery and supplies power for engine
instruments and accessories. A 12-volt starter motor (approximately
2.0-2.5 kW) engages the flywheel ring gear. The electrical harness
includes marine-grade sealed connectors and corrosion-resistant
terminals.
Turbocharger and Aftercooler System: The engine is equipped with a
single, fixed-geometry turbocharger. A wastegate is not present on
standard TAMD31 variants; boost pressure is controlled by turbine
housing geometry and exhaust flow. The aftercooler is of the
air-to-freshwater type, using engine coolant rather than seawater as the
cooling medium, preventing saltwater corrosion inside the aftercooler
core.
Engine Mounts: Adjustable rubber engine mounts isolate vibration from
the hull. Mount tightening torque is 185 Nm (136 lb-ft) for standard
mounts and 230 Nm (170 lb-ft) for V-drive installations. Nominal mount
height is 106 ± 5 mm (4.2 ± 0.2 in) for V-drive configurations.
Overall Engine Length (Front Pulley to Flywheel Housing): 1,150 mm (45.3
in)
Overall Engine Width: 687 mm (27.0 in)
Overall Engine Height: 738 mm (29.1 in)
Dry Weight (TAMD31L, Complete, No Fluids): 409 kg (902 lb)
Dry Weight (TAMD31A, Complete): 510 kg (1,124 lb)
Dry Weight (TAMD31P, Standard Configuration): 400 kg (882 lb)
Engine Oil:
Grade: SAE 15W-40 (diesel-rated, API CF-4, CG-4, or CH-4)
Oil Capacity (With Filter, Standard Pan): 10.5 L (11.1 qt)
Normal Oil Pressure (Rated Speed, Hot): 350-450 kPa (51-65 psi)
Minimum Oil Pressure (Hot Idle): 70 kPa (10 psi)
Engine Oil Change Interval: Change every 250 operating hours or annually
Oil Filter Change Interval: Replace at every oil change
Cooling System (Freshwater Circuit):
Coolant Type: Diesel-rated ethylene glycol antifreeze (50/50 mix with
distilled water)
Total Freshwater Capacity (Engine and Heat Exchanger): 7.5-8.5 L
(7.9-9.0 qt)
Thermostat Opening Temperature: 82°C (180°F)
Heat Exchanger Pressure Cap Rating: 0.7-1.0 bar (10-15 psi)
Coolant Change Interval: Drain, flush, and refill every 2 years or 500
operating hours.
Valve Clearance (Cold Engine, Ambient
Temperature):
Intake: 0.40 mm (0.016 in)
Exhaust: 0.40 mm (0.016 in)
Valve Adjustment Interval: Inspect and adjust every 500 operating hours
or annually.
Fuel Filter Change Interval (Water Separator and Secondary): Replace
every 250 hours or annually.
Injector Testing Interval: Test injector opening pressure and spray
pattern every 500-1,000 hours.
Aftercooler Maintenance: Remove and clean seawater side of heat
exchanger every 500-1,000 hours.
Impeller Replacement (Seawater Pump): Replace rubber impeller every
250-500 hours or annually.
Cylinder Head Bolts, Step 1: 30 Nm (22 lb-ft).
Cylinder Head Bolts, Step 2: 60 Nm (44 lb-ft).
Cylinder Head Bolts, Step 3: 100 Nm (74 lb-ft).
Connecting Rod Cap Bolts: 50 Nm (37 lb-ft).
Main Bearing Cap Bolts: 100 Nm (74 lb-ft).
Flywheel Bolts (to Crankshaft Flange): 80 Nm (59 lb-ft).
Crankshaft Pulley Bolt (Front Damper): 150 Nm (111 lb-ft).
Injection Pump Mounting Nuts (Gear-Driven Pump): 30 Nm (22 lb-ft).
High-Pressure Injection Lines (Injector End, Pump End): 25 Nm (18
lb-ft).
Injector Hold-Down Clamp Bolts: 25 Nm (18 lb-ft).
Intake Manifold Bolts: 25 Nm (18 lb-ft).
Exhaust Manifold Nuts: 35 Nm (26 lb-ft).
Turbocharger Mounting Nuts (to Exhaust Manifold): 40 Nm (30 lb-ft).
Turbocharger Oil Feed Line Fittings: 25 Nm (18 lb-ft).
Oil Pan Bolts (Cast Aluminum Pan): 18 Nm (13 lb-ft).
Valve Cover Bolts: 10 Nm (7 lb-ft).
Thermostat Housing Bolts: 20 Nm (15 lb-ft).
Water Pump Mounting Bolts (Freshwater Pump): 25 Nm (18 lb-ft).
Seawater Pump Mounting Bolts (Raw Water Pump): 22 Nm (16 lb-ft).
Starter Motor Mounting Bolts: 45 Nm (33 lb-ft).
Alternator Mounting Bracket Bolts: 35 Nm (26 lb-ft).
Glow Plugs (If Equipped): 15 Nm (11 lb-ft).
Oil Drain Plug (Oil Pan): 40 Nm (30 lb-ft).
Engine Mount Nuts (Standard Mounts): 185 Nm (136 lb-ft).
Engine Mount Nuts (V-Drive Mounts): 230 Nm (170 lb-ft).
The Volvo Penta TAMD31 engine was utilized as a primary marine
propulsion engine across a wide range of vessels.
Sailboats: Large, relatively
low-speed sailing yachts (TAMD31S variant, 100 hp @ 3,000 rpm)
Commercial Vessels:
Lifeboats and rescue boats (MED/SOLAS certified kits available)
Patrol craft and workboats
Small passenger vessels
Transmission Compatibility:
HS45A: Hydraulically shifted reverse gear with 8° down-angled shaft
HS25A: Hydraulic drop center transmission
MS25A/L: Mechanical drop center transmission with straight or
down-angled shafts
MS25S, MS25SR: Sailboat transmission variants with 2.2:1 reduction ratio
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