Yanmar 6LYA UTE Specifications
| Engine Model: Yanmar 6LYA UTE |
| Engine Type: 4-stroke inline 6-cylinder turbocharged water-cooled diesel |
| Total Displacement: 316 cu.in (5.18 L) |
| Rated Engine Power: 315 Hp (231.7 kW) at 3300 rpm |
| Fuel System Type: Direct injection |
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The Yanmar 6LYA-UTE (6LY-UTE) is a 6-cylinder,
4-stroke, water-cooled marine diesel engine from the 6LY series. This
power unit delivers high power density through a turbocharged and
seawater-cooled intercooled configuration combined with a mechanical
direct injection fuel system. The engine is installed in light-duty
commercial vessels, high-end pleasure craft, sportfishing yachts, and
fast patrol boats.
The Yanmar 6LYA-UTE is distinguished by its narrow, flat-top profile,
which permits installation in engine rooms with limited overhead
clearance. The mechanical injection system eliminates electronic control
complexity, supporting field serviceability away from major ports. The
engine shares service parts, including fuel and oil filters, with the
higher-output 6LYA-STE and 6LYA-STP variants.
Fresh water cooling with a rubber impeller seawater pump isolates the
engine block from corrosive seawater. The engine is governed to provide
a continuous rating of 260 hp at 3100 rpm and a maximum output of 315 hp
at 3300 rpm.
Engine Type: Inline 6-cylinder, 4-stroke, turbocharged, aftercooled
diesel
Displacement: 5.184 L (5184 cc / 316 cu.in)
Bore x Stroke: 100 mm x 110 mm (3.94 in x 4.33 in)
Compression Ratio: 16.5:1
Combustion System: Direct injection (mechanical)
Aspiration: Turbocharged with seawater-cooled intercooler
Valvetrain: OHV (Overhead Valve), 2 valves per cylinder, 12 valves total
Firing Order: 1-5-3-6-2-4
Direction of Rotation: Counter-clockwise as viewed from the stern
(flywheel end)
Maximum Output (crankshaft, intermittent): 231.7 kW (315 hp) at 3300 rpm
Continuous Rating (ISO 3046, commercial duty): 191.2 kW (260 hp) at 3100
rpm
Maximum Torque: 750 Nm (553 lb-ft) at 1900-2100 rpm
Low Idle Speed: 650-700 rpm
High Idle Speed (no-load, governed): 3450 rpm
Emission Standard: EPA Tier 2, IMO Tier II
The cylinder block is manufactured from cast iron with a closed-deck
design. Six cylinder bores are machined directly into the parent metal
without replaceable wet liners. The block features a siamese bore
configuration where each cylinder shares a common wall with adjacent
cylinders, maximizing rigidity and minimizing overall engine length. The
crankcase extends below the crankshaft centerline with a deep skirt
design.
Seven main bearing bulkheads support the crankshaft, with thrust bearing
position at the center main journal. The water jacket surrounds the full
height of each cylinder bore. Cast oil galleries run the entire length
of the block, supplying the main bearings, connecting rod bearings, and
camshaft bearings. A side-mounted spin-on oil filter and a
seawater-cooled oil cooler are integrated into the block casting on the
port side. Corrosion-resistant sacrificial anodes are threaded into the
block cooling passages.
Crankshaft: Forged steel with seven main journals. Seven counterweights
are integrated into the crank web. A viscous torsional vibration damper
is bolted to the crankshaft nose. Camshaft: Cast iron, located in the
cylinder block on the starboard side. Driven by a gear train from the
crankshaft. Camshaft bearings are replaceable steel-backed bronze
shells.
The cylinder head is a single-piece cast iron component with a
cross-flow intake and exhaust port arrangement. The intake ports are
located on the starboard side, and exhaust ports on the port side for
marine installations. Each cylinder features a bowl-in-piston combustion
chamber with the injector nozzle oriented vertically.
The valve train is an overhead valve (OHV) configuration with pushrods
and rocker arms. Each cylinder receives two valves: one intake and one
exhaust, arranged in a parallel valve layout. Valve stem seals are
positive-type on both intake and exhaust valves. Hardened steel valve
seat inserts on both sides resist wear under sustained high-load
operation. The camshaft is located in the cylinder block on the
starboard side.
Valve clearance adjustment uses a screw-and-locknut arrangement on the
rocker arms. The cold clearance specification for intake valves is 0.20
mm (0.008 in) and for exhaust valves is 0.25 mm (0.010 in). The rocker
shaft is supported by seven pedestals bolted directly to the cylinder
head. Glow plugs are installed in the intake ports for cold start
assistance.
The fuel system is a mechanical direct injection design with an in-line
injection pump. A Bosch in-line pump (P7100 series or equivalent) mounts
to the side of the timing gear case and delivers fuel to each cylinder
in the 1-5-3-6-2-4 firing order. The injection pump incorporates a
mechanical centrifugal governor with both idle and maximum speed control
springs. A manual stop lever permits mechanical fuel shutoff. Steel
injection lines route individually to each injection nozzle.
Injection nozzles are multi-hole type with an opening pressure of
18.0-18.5 MPa (2610-2680 psi). Injection timing is adjustable by shim
between the pump mounting flange and the pump base. A hand primer lever
on the lift pump permits manual bleeding of air after filter changes. A
primary fuel filter with water separator and a secondary spin-on filter
are mounted on the engine. The mechanical governor provides 8-12% droop
from no-load to full-load at rated speed.
The lubrication system uses a gear-type oil pump driven directly from
the crankshaft gear. The pump draws oil through a wire mesh suction
strainer positioned at the bottom of the marine oil pan. Oil passes
through a spin-on full-flow filter mounted on the port side of the
cylinder block. A seawater-cooled oil cooler, integrated into the block
casting, maintains oil temperature during sustained high-speed
operation. The oil cooler is a shell-and-tube design with seawater on
the tube side and engine oil on the shell side.
A pressure relief valve in the oil pump opens at 0.65-0.75 MPa (94-109
psi) to prevent over-pressurization during cold starts. Piston cooling
oil jets are present; six jets thread into the main oil gallery, each
directing a solid stream to the underside of each piston crown. Oil
pressure at rated speed measures 0.35-0.45 MPa (51-65 psi). A low oil
pressure switch triggers an audible alarm at 0.07 MPa (10 psi). Standard
oil pan capacity is 16.5 L (17.4 qt) including the filter.
The cooling system comprises two separate circuits: a high-temperature
fresh water circuit and a low-temperature seawater circuit. The fresh
water circuit cools the engine block, cylinder head, intercooler (air
side), and exhaust manifold. A belt-driven centrifugal fresh water pump
circulates coolant through the engine.
A copper-nickel heat exchanger integrates the two circuits. Seawater,
drawn through a hull strainer, passes through the heat exchanger shell
side, then through the intercooler water side and oil cooler, before
discharging through the exhaust mixing elbow. A wax-pellet thermostat
begins opening at 71°C (160°F) and reaches full opening at 85°C (185°F).
A bypass circuit permits fresh water circulation within the engine when
the thermostat remains closed. Coolant capacity (fresh water circuit,
including heat exchanger) is 15.0 L (15.9 qt). A seawater pressure
switch activates a warning device if flow drops below 0.8 bar (12 psi).
Sacrificial zinc anodes in the heat exchanger and intercooler prevent
galvanic corrosion.
Aspiration: Turbocharged with a fixed-geometry turbocharger mounted on
the starboard side. The turbocharger includes a seawater-cooled bearing
housing. Sequential turbocharging is not present on the UTE variant.
Intercooler: Seawater-cooled plate-type intercooler mounted on the
engine top. Seawater flows through the intercooler after passing through
the heat exchanger. Intake air temperature is reduced from 150°C (302°F)
at turbocharger outlet to 50°C (122°F) at intake manifold.
Combustion System: Direct injection with bowl-in-piston. The piston bowl
has a toroidal shape promoting air-fuel mixing. Injector nozzle has 5
holes (0.25 mm diameter each).
Cold Start System: Grid heater in the intake manifold or individual glow
plugs per cylinder depending on market specification. Glow plug
activation is controlled by a timer relay providing 5-10 second
pre-heat.
Electrical System: 12 V negative ground. Starter motor power rating is
2.5 kW, fitted with a marine-grade corrosion-resistant housing and water
protection. Alternator output is 80 A standard (optional 115 A).
Alternator drive is via a poly-ribbed belt with an automatic tensioner.
Exhaust System: Water-injected mixing elbow of nickel-aluminum-bronze
construction. Seawater injects at the elbow, reducing exhaust gas
temperature from 550°C (1022°F) to below 65°C (149°F) at the outlet. The
exhaust back pressure at rated power must not exceed 4.5 kPa.
Governor: Mechanical centrifugal governor integral to the injection
pump. Governing accuracy for constant-speed operation is ±20 rpm under
steady load.
Length (front pulley to flywheel housing face): 1175 mm (46.3 in)
Length (with KMH6A gearbox, propeller flange): 1460 mm (57.5 in)
Width (overall, exhaust elbow to injection pump): 790 mm (31.1 in)
Height (oil pan rail to rocker cover peak): 680 mm (26.8 in)
Height (flat-top profile from engine mounts to highest point): 570 mm
(22.4 in)
Dry Weight (engine without gearbox, without fluids): 593 kg (1307 lb)
Dry Weight (with KMH6A marine gearbox): 680 kg (1499 lb)
Engine Oil Change Interval: 250 hours or 12 months under normal marine
duty.
Engine Oil Capacity (including filter, standard oil pan): 16.5 L (17.4
qt).
Engine Oil Grade (ambient above 0°C / 32°F): SAE 15W-40, API CF-4 or
higher.
Engine Oil Grade (cold ambient -15°C to 0°C / 5°F to 32°F): SAE 10W-30.
Engine Oil Pressure Relief Valve Setting: 0.65-0.75 MPa (94-109 psi).
Engine Oil Pressure at Rated Speed: 0.35-0.45 MPa (51-65 psi).
Engine Oil Pressure at Low Idle (minimum, hot engine): 0.09 MPa (13
psi).
Coolant Capacity (fresh water circuit, engine + heat exchanger): 15.0 L
(15.9 qt).
Coolant Specification: Ethylene glycol base marine antifreeze with
low-silicate OAT formulation.
Thermostat Opening Temperature: 71°C (160°F) start; fully open at 85°C
(185°F).
Seawater Pump Impeller Replacement Interval: 500 hours or 12 months.
Heat Exchanger Zinc Anode Replacement Interval: 250 hours or 6 months in
saltwater operation.
Intercooler Zinc Anode Replacement Interval: 250 hours or 6 months.
Fuel Filter Replacement Interval (primary and secondary): 250 hours.
Air Filter Service Interval: Replace every 250 hours. Service indicator
replacement at 500 hours.
Valve Clearance (Cold Engine, Intake): 0.20 mm (0.008 in).
Valve Clearance (Cold Engine, Exhaust): 0.25 mm (0.010 in).
Valve Clearance Inspection Interval: 500 hours.
Injector Nozzle Opening Pressure: 18.0-18.5 MPa (2610-2680 psi).
Injector Nozzle Replacement Interval: 1500 hours or as indicated by
black smoke or reduced power.
Injection Timing (static): 14 deg BTDC at No. 1 cylinder (check by fuel
spill method).
Glow Plug Inspection: Check resistance every 500 hours.
Compression Pressure (std): 3.6-4.0 MPa (522-580 psi) at cranking speed
with injectors removed.
Compression Pressure Variation Between Cylinders: Maximum 0.25 MPa (36
psi) difference.
Turbocharger Inspection: Check for shaft end play every 1000 hours.
Turbocharger Inspection: Max allowable radial play is 0.15 mm (0.006
in). Max axial play is 0.05 mm (0.002 in).
Drive Belt Tension: Automatic spring tensioner. Replace belt every 1000
hours.
Idle Speed Adjustment (low, mechanical governor): 650-700 rpm via idle
stop screw on injection pump.
Cylinder Head Bolts (Stage 1): 50 Nm (37 lb-ft)
Cylinder Head Bolts (Stage 2): 120 Nm (89 lb-ft)
Connecting Rod Cap Bolts: 70 Nm (52 lb-ft)
Main Bearing Cap Bolts: 90 Nm (66 lb-ft)
Flywheel Bolts (to crankshaft flange): 120 Nm (89 lb-ft)
Flywheel Housing Bolts (to block, M12): 65 Nm (48 lb-ft)
Camshaft Drive Gear Nut: 180 Nm (133 lb-ft)
Camshaft Thrust Plate Bolts: 25 Nm (18 lb-ft)
Rocker Arm Shaft Bracket Bolts: 45 Nm (33 lb-ft)
Rocker Arm Adjusting Lock Nut: 20 Nm (15 lb-ft)
Valve Cover Nuts (with rubber gasket): 12 Nm (9 lb-ft)
Injection Pump Mounting Nuts (to timing case): 45 Nm (33 lb-ft)
Injection Pump Drive Gear Nut: 100 Nm (74 lb-ft)
Injection Line Fittings (pump end): 35 Nm (26 lb-ft)
Injection Line Fittings (nozzle end): 35 Nm (26 lb-ft)
Injector Hold-Down Clamp Nut: 35 Nm (26 lb-ft)
Crankshaft Pulley Bolt (center): 250 Nm (184 lb-ft)
Oil Pan Bolts (M8): 15 Nm (11 lb-ft)
Oil Pan Bolts (M10): 30 Nm (22 lb-ft)
Oil Pan Drain Plug (magnetic): 70 Nm (52 lb-ft)
Oil Filter (spin-on canister): Hand tighten plus 3/4 turn, or 20 Nm (15
lb-ft)
Oil Cooler Mounting Bolts (to block): 50 Nm (37 lb-ft)
Fresh Water Pump Mounting Bolts: 30 Nm (22 lb-ft)
Heat Exchanger Mounting Bolts (to block): 45 Nm (33 lb-ft)
Seawater Pump Mounting Bolts: 30 Nm (22 lb-ft)
Seawater Pump Cover Bolts (impeller access): 15 Nm (11 lb-ft)
Thermostat Housing Bolts: 25 Nm (18 lb-ft)
Exhaust Manifold Bolts (to cylinder head): 50 Nm (37 lb-ft)
Exhaust Mixing Elbow Bolts (to manifold): 45 Nm (33 lb-ft)
Turbocharger Mounting Nuts (to manifold): 50 Nm (37 lb-ft)
Turbocharger Oil Supply Line Fitting: 30 Nm (22 lb-ft)
Intercooler Mounting Bolts (to engine top): 35 Nm (26 lb-ft)
Starter Motor Mounting Bolts (M12): 80 Nm (59 lb-ft)
Alternator Mounting Bolts (pivot and adjuster): 45 Nm (33 lb-ft)
Alternator B+ Terminal Nut: 10 Nm (89 lb-in)
Glow Plug (if fitted, in cylinder head): 25 Nm (18 lb-ft)
Engine Mount Bracket Bolts (to block): 100 Nm (74 lb-ft)
Zinc Anode Plugs (heat exchanger, two plugs): 25 Nm (18 lb-ft)
Zinc Anode Plug (intercooler): 20 Nm (15 lb-ft)
Fresh Water Coolant Drain Plug (block): 30 Nm (22 lb-ft)
Sportfishing Yachts: Single or twin installations in vessels from 35 ft
to 45 ft (10.7 m to 13.7 m). Models include Bertram 31 with repower,
Tiara 3500 Pursuit, Luhrs 36 Convertible, Albemarle 32 Express. The
flat-top profile suits under-deck mounting in low-profile cockpit sole
engine boxes.
Pleasure Craft: Fast cruisers and express cruisers. Downeast-style
lobster yachts. Motor yachts up to 15 m (49 ft) requiring 20-25 knot
cruise speeds.
Light Commercial Vessels: Harbour patrol boats (up to 12 m). Pilot boats
and launch vessels. Small fish trawlers in coastal fleets. Aquaculture
service craft. Customs and law enforcement interceptors.
Lifeboat and Rescue Craft: Davit-launched enclosed lifeboats for
offshore supply vessels. Fast rescue craft (FRC) for coast guard
operations. RNLI-style inshore rescue boats (commercial variants).
Passenger Vessels: Small passenger ferries (up to 12 m) on short inland
routes. Water taxis and tour boats in protected water operations.
Workboats: Tender vessels for larger ships. Dive support boats. Research
vessels for coastal survey work. Small utility barges (as propulsion
unit on push boats).
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