Yanmar 6LP STE Specifications
| Engine Model: Yanmar 6LP STE |
| Engine Type: 4-stroke inline 6-cylinder turbocharged water-cooled diesel |
| Total Displacement: 254.1 cu.in (4.16 L) |
| Rated Engine Power: 300 Hp (221 kW) at 3800 rpm |
| Fuel System Type: Direct injection |
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The Yanmar 6LP-STE is a 6-cylinder,
turbocharged and intercooled marine diesel engine from the Yanmar LP
series. This predecessor to the later 6LPA-STP2 was engineered for
high-output marine applications including pleasure craft, yachts, light
commercial vessels, and fishing boats. The engine employs a direct
injection system with a Bosch VE6 distributor-type injection pump.
The Yanmar 6LP-STE features a 2-valve per cylinder cylinder head,
distinguishing it from the 4-valve design introduced on subsequent "A"
series models (6LPA). A waste-gated, water-cooled turbocharger combined
with an intercooler provides forced induction. The engine is configured
for constant high-temperature fresh water cooling with a heat exchanger,
separating the internal coolant circuit from external seawater
circulation. The Yanmar 6LP-STZE variant, equipped with a Mercruiser
Bravo Three sterndrive, is recognized for delivering fuel economy
advantages over twin gasoline outboard configurations on comparable
vessels.
Engine Type: 4-stroke, vertical, water-cooled inline diesel.
Number of Cylinders: 6.
Valvetrain: Overhead valve (OHV), 2 per cylinder (12 valves total).
Displacement: 4164 cc (4.164 L / 254.1 cu.in).
Bore x Stroke: 94 mm x 100 mm (3.70 in x 3.94 in).
Compression Ratio: 18.8:1.
Combustion System: Direct injection.
Aspiration: Turbocharged and intercooled, with waste-gated.
Maximum Output (Crankshaft): 221 kW (300 hp) at 3800 rpm.
Continuous Rating: 188 kW (255 hp) at 3600 rpm.
Maximum Torque: 642 Nm (474 lb-ft) at 2200 rpm.
Fuel Consumption at WOT: Approximately 54.5 L/h (14.4 gal/h).
Emission Compliance: EPA Tier 2, IMO, EU Stage IIIA.
Direction of Rotation: Counterclockwise viewed from the flywheel (stern
side) for standard configurations; clockwise rotation variants exist for
specific applications.
The cylinder block is manufactured from cast iron, providing a rigid
foundation for the inline 6-cylinder configuration. This construction
ensures durability under the high cylinder pressures generated by
turbocharged operation. The block design incorporates five main bearing
journals supporting the crankshaft.
The water jacket surrounds each cylinder bore to ensure uniform heat
dissipation. The crankcase ventilation system uses a breather mounted on
the block. A piston cooling oil nozzle system is integrated, directed at
the underside of each piston crown to manage thermal loads under high
boost conditions.
The cylinder head is constructed from cast aluminum alloy, balancing
weight reduction with thermal conductivity. The overhead valve (OHV)
arrangement uses a camshaft located in the cylinder block with valve
actuation via pushrods and rocker arms. Each cylinder receives two
valves: one intake and one exhaust.
This 2-valve configuration distinguishes the 6LP-STE from later 4-valve
"A" series models. The valve seats are manufactured from heat-resistant
alloy steel. The valvetrain requires periodic manual valve clearance
adjustment. The cylinder head assembly includes locations for the fuel
injection nozzles and glow plugs to assist cold starting.
The fuel system is a direct injection design using a Bosch VE6
distributor-type injection pump. The pump is mounted on the engine and
driven by the timing gears. A mechanical fuel feed pump draws fuel from
the tank through a fuel strainer. The distributor pump uses a single
plunger to generate high pressure and a rotary distributor head to
direct fuel to each cylinder in the firing order sequence.
High-pressure steel lines deliver fuel to the individual injection
nozzles located in the cylinder head. A fuel cooler is incorporated into
the system to maintain fuel temperature within operational limits. A
fuel filter with an integrated water separator is mounted between the
fuel tank and the feed pump.
The lubrication system is a forced-feed, pressurized design using a
trochoid gear pump. The pump draws oil from the oil sump through a
suction strainer. Pressurized oil passes through a full-flow oil filter.
An oil cooler is integrated into the system to maintain lubricant
temperature under continuous high-load operation.
The bearing journals receive pressurized oil through the main gallery.
The total oil capacity is 11.0-13.0 liters (2.9-3.4 gal), depending on
the oil pan configuration. A piston cooling oil nozzle system directs
oil to cool each piston. The oil pan includes a drain plug.
The cooling system is a dual-circuit, seawater-to-freshwater heat
exchanger design. The freshwater (closed) circuit uses a centrifugal
water pump circulated by the front belt drive. Coolant passes through
the cylinder block, cylinder head, and the freshwater side of the heat
exchanger. A thermostat controls flow to maintain operating temperature.
The seawater circuit uses a flexible impeller-type pump. Seawater is
drawn through a hull strainer, circulated through the seawater side of
the heat exchanger and the oil cooler, then discharged into the exhaust
injection elbow. The freshwater capacity is 8.3 liters (2.2 gal). The
seawater circuit volume is 15.1 liters (4.0 gal) depending on
installation configuration.
| Intake and Exhaust Systems |
Intake System: The intake manifold is fed by the turbocharger
compressor. Compressed air passes through an intercooler (air cooler)
before entering the intake manifold. The air duct routes airflow from
the air cleaner to the turbocharger inlet.
Exhaust System: The exhaust manifold collects gases from all six
cylinders. A water-cooled turbocharger is mounted to the exhaust
manifold. Exhaust gases then pass through a water-injected exhaust elbow
where seawater is introduced for cooling and silencing. The exhaust bend
directs the combined flow to the vessel's exhaust system.
The engine is equipped with a 12V electric starting system with a 2.5 kW
starter motor. An 80A alternator provides charging capacity. Glow plugs
assist cold starting. An instrument panel with tachometer, temperature
gauge, oil pressure gauge, and audible alarms is available as an option.
Turbocharging System: A waste-gated turbocharger provides boost
pressure. A boost control mechanism regulates the wastegate actuator to
limit maximum boost pressure.
Marine Gear: The engine couples to various marine gear options including
KMH series hydraulic transmissions and ZF marine gears. The 6LP-STZE
variant is specifically configured for Mercruiser Bravo Three sterndrive
applications.
Overall Length (Engine Only): 1015-1065 mm (40.0-41.9 in).
Overall Width: 671-754 mm (26.4-29.7 in).
Overall Height: 729-789 mm (28.7-31.1 in).
Dry Weight (Engine Only): 408-500 kg (899-1102 lb).
Dry Weight with Z Drive: 428 kg (943 lb).
Engine Oil Capacity (with filter): 11.0-13.0 L (2.9-3.4 gal).
Engine Oil Specification: API CF, CF-4, or CI-4. SAE 15W-40, 5W-30 or
10W-30.
Oil Change Interval: 125 hours or 6 months for normal-duty operation.
Oil Change Interval: 250 hours for light-duty.
Oil Filter Change Interval: Every oil change.
Fuel Filter Change Interval: 250 hours.
Fuel Filter Water Drain: Inspect regularly; drain when water is present.
Coolant Capacity (Freshwater Circuit): 8.3 L (2.2 gal).
Coolant Specification: Ethylene glycol-based antifreeze with corrosion
inhibitors.
Coolant Change Interval: 250 hours or 12 months.
Seawater Pump Impeller Change: 200 hours or 12 months.
Valve Clearance Adjustment Interval: 500 hours.
Idle Speed Restoration: 700-750 rpm.
Maximum Compression Variation Between Cylinders: 10%.
Air Cleaner Service: Inspect and clean as needed.
Engine Mount Inspection: Annually or 500 hours.
Cylinder Head Bolts: 118 ± 10 Nm (87 ± 7 lb-ft)
Main Bearing Cap Bolts: 118 ± 10 Nm (87 ± 7 lb-ft)
Connecting Rod Cap Bolts: 69 ± 5 Nm (51 ± 4 lb-ft)
Flywheel Bolts: 118 ± 10 Nm (87 ± 7 lb-ft)
Camshaft Bearing Cap Bolts: 25 ± 3 Nm (18 ± 2 lb-ft)
Rocker Arm Shaft Bracket Bolts: 25-30 Nm (18-22 lb-ft).
Rocker Arm Adjustment Locknut: 10 Nm (7 lb-ft).
Injector Clamp Bolts: 27 ± 3 Nm (20 ± 2 lb-ft)
High-Pressure Fuel Line Nuts: 18-22 Nm (13-16 lb-ft).
Glow Plugs: 15-20 Nm (11-15 lb-ft)
Oil Filter (spin-on): 18-22 Nm (13-16 lb-ft)
Oil Pan Bolts: 20 ± 3 Nm (15 ± 2 lb-ft)
Water Pump Mounting Bolts (Seawater): 15-20 Nm (11-15 lb-ft).
Water Pump Mounting Bolts (Freshwater): 20-25 Nm (15-18 lb-ft).
Thermostat Housing Bolts: 15 ± 2 Nm (11 ± 1 lb-ft)
Intake Manifold Bolts: 15-20 Nm (11-15 lb-ft).
Exhaust Manifold Nuts: 20-25 Nm (15-18 lb-ft).
Turbocharger Mounting Nuts: 44 ± 5 Nm (32 ± 4 lb-ft)
Starter Motor Mounting Bolts: 44 ± 5 Nm (32 ± 4 lb-ft)
Alternator Pivot and Adjusting Bolts: 44 ± 5 Nm (32 ± 4 lb-ft)
Injection Nozzle Holders: 50-60 Nm (37-44 lb-ft).
Pleasure Craft (30-40 ft / 9-12 m): High-performance yachts and
speedboats. Used as a repower engine for gas-to-diesel conversions.
Fishing Vessels: Commercial and recreational fishing boats, including
offshore sportfishing vessels, benefit from the fuel economy and
extended cruising range.
Workboats (Light Commercial): Tugboats, pilot boats, and patrol vessels
requiring durability and performance under continuous load.
Sailboat Auxiliary Propulsion: Larger cruising sailboats requiring high
auxiliary power.
6LP-STZE Variant (Sterndrive): The engine with the Mercruiser Bravo
Three sterndrive is installed in open console fishing boats and fast
cruisers.
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