Yanmar 6LP DTE Specifications
| Engine Model: Yanmar 6LP DTE |
| Engine Type: 4-stroke inline 6-cylinder turbocharged water-cooled diesel |
| Total Displacement: 254 cu.in (4.16 L) |
| Rated Engine Power: 250 Hp (184 kW) at 3800 rpm |
| Fuel System Type: Direct injection |
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The Yanmar 6LP-DTE is a 6-cylinder, vertical,
4-cycle water-cooled marine diesel engine featuring direct injection,
turbocharging, and intercooling. This powerplant was marketed with a
maximum output of 250 hp (184 kW) at 3800 rpm, making it suitable for
planing hulls and light commercial vessels including sport cruisers,
fishing boats, and patrol craft. The engine employs a Bosch VE6
distributor-type injection pump with an all-speed mechanical governor, a
configuration chosen for its simplicity and reliability in marine
environments.
A timing belt drives the camshaft, characteristic of an interference
engine design where piston-to-valve clearance is zero if the belt fails;
replacement intervals are specified at 1250 hours or 5 years. The fresh
water cooling system with a heat exchanger isolates engine coolant from
seawater, reducing internal corrosion. The 12-volt electrical system
includes a 2.5 kW starter motor and an 80A alternator.
The Yanmar 6LP-DTE is an inline, six-cylinder, four-cycle, water-cooled
diesel engine. Its architecture employs direct injection combustion with
a swirl-type piston bowl design optimized for the turbocharged
aspiration system. The engine rotates clockwise when viewed from the
flywheel side. The Bosch VE6 distributor injection pump provides fuel
distribution, while the all-speed mechanical governor maintains stable
operation from idle to full load. A seawater-cooled intercooler reduces
intake air temperature after the turbocharger compressor.
Engine Type: Inline 6-cylinder, 4-cycle, water-cooled diesel
Configuration: Vertical, 6-cylinder
Displacement: 4.163 L (254 cu.in)
Bore x Stroke: 94 mm x 100 mm (3.70 in x 3.94 in)
Compression Ratio: 18.0:1
Combustion System: Direct Injection
Aspiration: Turbocharged with Intercooler
Maximum Output (Crankshaft): 184 kW (250 hp) @ 3800 rpm
Continuous Rating: 154 kW (210 hp) @ 3600 rpm
Firing Order: 1-4-2-6-3-5
Direction of Rotation: Clockwise viewed from flywheel
Injection Pump: Bosch VE6 Distributor type
Governor: All-speed mechanical
The cylinder block is a single-piece, inline construction manufactured
from high-grade cast iron. This material provides the rigidity required
to withstand combustion pressures generated by the turbocharged direct
injection system. The block uses a parent-bore design with
induction-hardened cylinder bores finished to a plateau honed surface.
Six main bearing bulkheads support the crankshaft, each secured by four
bolts for increased rigidity under high cylinder pressures.
The crankcase forms a deep-skirt design extending below the crankshaft
centerline, with the oil pan mounting face integrated into the block
structure. The water jacket surrounds all six cylinders fully, supplied
by the fresh water pump through cast-in passages. Piston cooling oil
jets are installed in the crankcase, directing lubricant to the
underside of each piston crown.
The cylinder head is manufactured from cast aluminum alloy, reducing
overall engine weight for marine installations. The cross-flow design
positions intake ports on one side and exhaust ports on the opposite
side, minimizing heat transfer from the exhaust manifold to the incoming
air charge. Each of the six cylinders features four valves arranged
symmetrically: two intake valves and two exhaust valves, totaling
twenty-four valves for the complete engine. Valves are made from
heat-resistant steel with hardened tips. Valve seats are pressed-in
inserts made from sintered alloy material.
Valve actuation occurs via a single overhead camshaft driven by a timing
belt. Roller rocker arms transfer camshaft motion to the valves,
reducing frictional losses. Valve clearance adjustment is performed
using setscrews and locknuts at the rocker arm tips. The centrally
located fuel injector passes through the cylinder head between the four
valves, directing the fuel spray directly into the piston bowl
combustion chamber. Glow plugs are installed in each cylinder as a cold
starting aid.
The fuel system is a direct injection architecture with a Bosch VE6
distributor-type injection pump. A self-priming diaphragm-type fuel lift
pump draws fuel from the tank and delivers it through a replaceable
cartridge-type fuel filter with an integral water separator. A fuel
strainer and fuel cooler are incorporated in the system. The injection
pump is mounted on the engine and driven by the gear train.
This pump contains a single plunger that distributes fuel sequentially
to each of the six cylinders through a rotating distributor head. An
all-speed mechanical governor integrated into the injection pump
maintains engine speed under varying load by adjusting fuel delivery
volume. A boost compensator adjusts fuel delivery based on turbocharger
boost pressure, preventing smoke during acceleration.
High-pressure injection lines, manufactured from seamless steel tube,
carry fuel from the pump to the six injection nozzles. Each nozzle is a
multi-hole injector with an opening pressure calibrated to the engine
specification. Excess fuel from the injection pump and injectors returns
to the tank through a spill line. A manual priming lever on the lift
pump allows system priming after filter changes.
The lubrication system is a forced-feed, wet-sump configuration with a
full-flow filtration circuit. A trochoid-type oil pump, mounted on the
engine front cover and driven by the crankshaft, draws oil from the sump
through a screened pick-up tube. A spring-loaded pressure relief valve
maintains system pressure within a calibrated range.
Oil passes through a full-flow spin-on cartridge filter containing a
paper filtration element with a bypass valve that opens when filter
restriction exceeds calibration. Pressurized oil is distributed through
internal galleries to the seven main bearings, six connecting rod
bearings via drilled crankshaft passages, camshaft bearings, rocker arm
shaft, turbocharger bearing cartridge, and injection pump drive.
Piston cooling oil jets direct oil to the underside of each piston
crown. A plate-type oil cooler, using engine fresh water as the exchange
medium, maintains oil temperature within operational limits. An oil
dipstick passes through the cylinder block into the sump for level
checks. The oil pan is a fabricated steel component with a drain plug at
its lowest point.
The cooling system is a dual-circuit design: a pressurized fresh water
circuit for engine cooling and a separate seawater circuit for heat
rejection. The fresh water circuit is thermostatically regulated. A
belt-driven, centrifugal fresh water pump circulates coolant through the
cylinder block, cylinder head, turbocharger center housing, oil cooler,
and the heat exchanger. A wax-pellet thermostat maintains operating
temperature by controlling coolant flow to the heat exchanger.
The heat exchanger is a shell-and-tube type where fresh water flows
inside tubes while seawater passes over the tube bundle. The seawater
circuit uses a rubber-impeller, positive-displacement pump driven by the
front belt system. Seawater is drawn through a strainer, then passes
through the heat exchanger, the charge air cooler (intercooler), and the
water-injected mixing elbow before discharge overboard. An expansion
tank accommodates thermal expansion and provides de-aeration.
| Intake and Exhaust Systems |
Intake System: Air enters through a flame arrestor, passes through the
turbocharger compressor housing, then through the seawater-cooled charge
air cooler (intercooler), and finally into the intake manifold. The
intake manifold distributes air equally to all six cylinders.
Exhaust System: The exhaust manifold is a single-piece cast iron
component. Exhaust gases exit the cylinder head, drive the turbocharger
turbine wheel, then pass through the water-cooled mixing elbow where
seawater is injected to cool gases before entering the exhaust hose and
overboard discharge.
Starting System: A 12-volt electric starting system is standard, with a
2.5 kW starter motor. A solenoid-shift mechanism engages the pinion gear
with the ring gear mounted on the flywheel before supplying full
cranking current. Glow plugs provide cold starting assistance,
energizing for 5-10 seconds before cranking.
Charging System: A 12-volt alternator charges the battery and powers
vessel electrical loads. Standard alternator output is 80A. The
alternator is driven by a poly-V belt with an automatic tensioner.
Timing System: A timing belt drives the camshaft. This is an
interference engine design where piston-to-valve clearance is zero.
Timing belt replacement interval is specified at 1250 hours or 5 years.
Length: 1070 mm (42.1 in)
Width: 770 mm (30.3 in)
Height: 880 mm (34.6 in)
Dry Weight (without transmission): 380 kg (838 lb)
Timing Belt Replacement: Every 1250 hours or 5 years
Valve Clearance Inspection: Every 500 hours
Fuel Filter Replacement: Every 250 hours
Seawater Pump Impeller Inspection: Every 200 hours
Seawater Pump Impeller Replacement: Every 500 hours or 12 months
Drive Belt Inspection: Every 250 hours
Oil and Oil Filter Change: Every 250 hours or 12 months
Initial Oil Change (first 50 hours): Required
Coolant Replacement: Every 1000 hours or 24 months
Injection Nozzle Inspection: Every 800 hours
Engine Oil Capacity (with filter): 7.0 L (7.4 qt)
Recommended Oil Grade: SAE 15W-40 (API CI-4 or higher)
Engine Coolant Capacity (engine + heat exchanger): 8.4 L (8.9 qt)
Recommended Coolant: Ethylene glycol-based antifreeze
Valve Clearance (intake and exhaust, cold): 0.20 mm (0.008 in)
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 Support Bolts: 44 ± 5 Nm (32 ± 4 lb-ft)
Rocker Arm Adjusting Locknuts: 15 ± 2 Nm (11 ± 1 lb-ft)
Injector Clamp Bolts: 27 ± 3 Nm (20 ± 2 lb-ft)
High-Pressure Injection Line Nuts: 25-30 Nm (18-22 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: 25 ± 3 Nm (18 ± 2 lb-ft)
Thermostat Housing Bolts: 15 ± 2 Nm (11 ± 1 lb-ft)
Intake Manifold Nuts: 25 ± 3 Nm (18 ± 2 lb-ft)
Exhaust Manifold Nuts: 44 ± 5 Nm (32 ± 4 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)
The Yanmar 6LP-DTE engine is designed for marine propulsion in
recreational and light commercial vessels.
Sport Cruisers: Planing hull powerboats of 8-12 meters length requiring
200-250 horsepower.
Cabin Cruisers: Express cruisers and flybridge motor yachts for coastal
cruising.
Fishing Vessels: Small to medium commercial fishing boats and sport
fishing vessels.
Patrol and Pilot Craft: Light commercial planing craft including patrol
boats, pilot boats, and water taxis.
RIBs (Rigid Inflatable Boats): Large RIBs for military, law enforcement,
and commercial use.
Sterndrive Configurations: Units set up to connect to Mercruiser Bravo
sterndrive systems.
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