John Deere 6068HFG20 Specifications
| Engine Model: John Deere PowerTech M 6068HFG20 |
| Engine Type: 4-stroke in-line 6-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 415 cu.in (6.8 L) |
| Rated Engine Power: 223-282 Hp (166-210 kW) at 1500-1800 rpm |
| Fuel System Type: Direct Injection |
____________________________________________________________________________________
The John Deere 6068HFG20 is a 6.8-liter,
6-cylinder diesel engine drawn from the PowerTech M product family,
purpose-engineered for generator drive applications. Unlike its Tier 3
counterpart (the 6068HF485), the HFG20 variant carries a non-certified
emission classification, allowing operation in regions with limited
regulatory frameworks such as certain African, South American, and
Southeast Asian markets.
The engine is optimized for dual-frequency operation, switchable between
50 Hz (1500 rpm) and 60 Hz (1800 rpm) generator sets. A distinctive
mechanical rotary fuel pump from Stanadyne replaces high-pressure common
rail systems found in later PowerTech E engines. This choice ensures
compatibility with high-sulfur fuel (up to 5000 ppm) and simplifies
field maintenance. Turbocharging with air-to-air aftercooling delivers a
dense charge air volume for sustained standby and prime power output.
The design prioritizes long service intervals: 500 hours for oil and
fuel filter changes, with a 4000-hour coolant replacement interval. All
service points are grouped on the right-hand side of the engine to
reduce maintenance time in enclosed generator enclosures. Applications
include standby generators for hospitals, telecommunications towers, and
industrial facilities, as well as prime power units for remote mining
and construction camps.
The John Deere 6068HFG20 is an inline, 6-cylinder, 4-cycle turbocharged
diesel engine with air-to-air aftercooling. The engine operates at a
fixed governed speed matching the generator frequency: 1500 rpm for 50
Hz grids or 1800 rpm for 60 Hz grids. The design excludes an electronic
control unit (ECU) for fuel management, relying instead on a mechanical
pump with an electronic governor overlay for frequency stability.
Engine Type: In-line, 6-cylinder, 4-cycle turbocharged diesel.
Displacement: 6.8 L (415 cu.in).
Bore x Stroke: 106 mm x 127 mm (4.19 in x 5.00 in).
Compression Ratio: 17.0:1.
Aspiration: Turbocharged and air-to-air aftercooled (ATAAC).
Firing Order: 1-5-3-6-2-4.
Frequency Switching: The engine is mechanically capable of 1500 rpm (50
Hz) and 1800 rpm (60 Hz) operation via governor adjustment and generator
reconnection. No hardware changes are required for the engine itself.
50 Hz Performance (1500 rpm):
Standby Power: 183 kW (245 hp).
Prime Power: 166 kW (223 hp).
60 Hz Performance (1800 rpm):
Standby Power: 210 kW (282 hp).
Prime Power: 189 kW (253 hp).
The cylinder block is cast from high-strength gray iron with a
deep-skirt architecture extending below the crankshaft axis. This
configuration provides seven main bearing supports for the crankshaft,
one between each cylinder plus end supports. The block incorporates
replaceable wet-type cylinder liners made of centrifugally cast alloy
iron. Each liner features a hardened internal bore surface finished with
a plateau hone.
Two O-rings at the liner base seal coolant, while a fire ring at the top
seals combustion gases. A directed top-liner cooling system forces
coolant at high velocity around the upper 30 mm (1.18 in) of each liner
to remove piston ring friction heat. The block casting includes a
side-mounted oil filter housing, a water pump mounting face at the
front, and a rear face drilled for the flywheel housing. A structural
oil pan, fabricated from steel, attaches to the block via a perimeter
flange with 22 bolts.
The cylinder head is a single-piece, cast-iron cross-flow design
spanning all six cylinders. Four valves per cylinder (two intake, two
exhaust) produce a total of 24 valves. The intake ports generate a swirl
ratio of 1.8 to 2.2, promoting complete combustion without white smoke
at light loads. The exhaust ports collect into two separate passages
before merging at the turbocharger inlet flange. Valve seats are
sintered powder metal, induction-hardened to 50 HRC minimum.
Valve guides are of the semi-finished type, requiring reaming after
installation to correct any bore distortion. The valvetrain operates via
a camshaft located in the cylinder block. Pushrods transfer motion to
cast iron rocker arms with a 1.5:1 ratio. Mechanical lash adjusters
(screw and locknut) are used, not hydraulic adjusters. This design
requires periodic valve clearance inspection. The cylinder head gasket
is a multi-layer steel (MLS) construction with six independent fire
rings and silicone bead sealing for fluid passages.
The fuel system employs a mechanical rotary distributor-type injection
pump manufactured by Stanadyne (model DB4429 or equivalent), combined
with an electronic governor actuator. The pump draws fuel through a
primary spin-on filter with an integral water separator and a secondary
inline filter. A gear-type transfer pump, integral to the injection
pump, supplies fuel at low pressure to the distributor head.
One high-pressure pumping plunger, actuated by a cam ring, pressurizes
fuel. A rotating distributor rotor directs the high-pressure fuel to
each cylinder in the firing order 1-5-3-6-2-4. Six mechanical injectors,
one per cylinder, open at a calibrated crack pressure of 2800 psi (193
bar) and deliver fuel directly into the combustion bowl in the piston
crown.
The electronic governor, a magnetic speed sensor mounted on the flywheel
housing, sends engine speed signals to a dedicated governor control
module. This module commands an electric actuator on the injection pump
to adjust the fuel rack position, maintaining frequency within ±0.5%
under steady-state load. The system tolerates high-sulfur fuel without
degradation of internal pump components. No ECU is present for overall
engine management.
The lubrication system is a pressurized, full-flow filtration circuit
with a forced-feed design. A gear-type oil pump, mounted to the front of
the crankshaft, draws oil through a fixed strainer from a pressed steel
sump. The sump capacity is enlarged for generator duty to accommodate
extended service intervals. Oil passes through a single spin-on
full-flow filter with a bypass valve set at 25 psi (172 kPa).
The filter head incorporates an integral water-cooled oil cooler,
stacked within the engine coolant circuit. Pressurized oil then travels
to the seven main bearings, six connecting rod bearings, camshaft
bearings, rocker shaft, and tappets. Piston cooling jets are not
installed on the HFG20, as the generator application does not produce
the sustained high torque loads found in traction engines. The oil pan
includes a dipstick tube and a threaded drain plug at the lowest point.
Total Oil Capacity (with filter): 32 L (34 qt). This increased capacity
over industrial versions supports the 500-hour change interval.
Recommended Oil Grade: John Deere Plus-50 II SAE 15W-40, or any oil
meeting API CF or higher specification. For high-sulfur fuel operation
(above 5000 ppm), an oil with a total base number (TBN) of 12 minimum is
required. Oil Pressure (rated speed, warm engine): 345 kPa (50 psi). Oil
Pressure (idle, warm engine): Minimum 105 kPa (15 psi).
The cooling system is a sealed, pressurized, thermostatically controlled
circuit. A belt-driven centrifugal water pump circulates coolant through
the cylinder block and cylinder head. The system operates in series:
coolant first passes through the oil cooler, then the cylinder block
water jacket (directed top-liner cooling zone), then the cylinder head,
then exits to the radiator top tank.
A bypass passage permits circulation within the engine block during
warm-up. The thermostat is a wax-pellet, single-stage unit mounted in a
housing at the front of the cylinder head. A deaeration line from the
top of the thermostat housing routes air to the surge tank. The radiator
fan is belt-driven with a viscous clutch; generator sets often replace
this with an electric pusher fan or a separate engine room ventilation
system.
Engine Coolant Capacity (engine only, without radiator): 11.3 L (12 qt).
Thermostat Start Opening Temperature: 82°C (180°F).
Thermostat Fully Open Temperature: 95°C (203°F).
Maximum Coolant Pressure (radiator cap rating): 15 psi (103 kPa).
Recommended Coolant: John Deere Cool-Gard II or a low-silicate ethylene
glycol antifreeze with supplemental coolant additive (SCA) for wet liner
cavitation protection. Concentration: 50% antifreeze, 50% distilled
water.
| Intake and Exhaust Systems |
Air Intake System: A heavy-duty, two-stage dry-type air cleaner with a
radial seal element and a dust evacuation valve. The air cleaner is
sized for 1200 cfm at rated speed. A restriction indicator (mechanical
pop-up type) is located on the clean air side.
Exhaust System: A dry-type exhaust manifold with divided passages
(cylinders 1-2-3 and 4-5-6) feeding the turbocharger turbine housing.
The turbine outlet is a 4-inch (102 mm) diameter flange for connection
to a flexible exhaust pipe. A spark arrestor muffler is available as an
option for indoor generator rooms.
Electrical System: Standard 12-volt negative ground, with a 75-amp
alternator and a gear-reduction starter motor rated at 4.5 kW. A 24-volt
option is available for remote starting applications, using two 12-volt
batteries in series and a 24-volt starter.
Cold Start Aid: An intake air grid heater (electric resistance type)
rated at 1500 watts. The heater activates automatically below 10°C
(50°F) and remains energized for 30 seconds after engine start. Manual
override is provided for tropical climates where the heater is
unnecessary.
Governor System: Electronic governor with actuator on the injection
pump. The control module accepts inputs from a magnetic pickup sensor
(flywheel teeth), a potentiometer for speed setting, and an emergency
stop contact. Frequency regulation: ±0.5% from no load to full load.
Isochronous governing is standard.
Turbocharger: A fixed-geometry wastegate turbocharger from BorgWarner or
Holset. The wastegate opens at 18 psi (124 kPa) boost pressure to
prevent overspeed during low load conditions. The compressor housing is
oriented for easy attachment of the charge air cooler piping.
Dry Weight (without flywheel, starter, alternator, or air cleaner): 569
kg (1250 lb).
Overall Length (front pulley to flywheel face): 1208 mm (47.5 in).
Overall Width (exhaust manifold outer to oil filter housing outer): 606
mm (23.8 in).
Overall Height (oil pan bottom to rocker cover top): 1037 mm (40.8 in).
Crankshaft Centerline Height (from bottom of oil pan): 345 mm (13.6 in).
Oil Change Interval: 500 hours for prime power duty with fuel sulfur
content below 0.5%. Reduce to 250 hours for high-sulfur fuel (above
0.5%) or dusty generator room environments. Oil Filter Replacement: At
every oil change. Use John Deere filter RE504836 or equivalent spin-on
element. Fuel Filter Replacement (primary): 500 hours. Drain water
separator weekly in humid climates. Fuel Filter Replacement (secondary):
500 hours, concurrent with primary.
Valve Clearance (cold engine, mechanical lash adjusters): Intake: 0.014
in (0.36 mm). Exhaust: 0.018 in (0.46 mm). Inspect every 1000 hours. Air
Cleaner Service: Replace primary element when restriction indicator
shows 25 in water (6.2 kPa). Maximum element life 1000 hours. Do not
clean paper elements. Replace secondary safety element every third
primary change. Coolant Replacement: 4000 hours or 2 years. Test SCA
concentration every 1000 hours. Radiator Cleaning: External fin cleaning
every 500 hours in dusty environments. Use compressed air from the fan
side outward.
Injector Service Interval: Test crack pressure and spray pattern every
2000 hours. Replace injectors at 4000 hours or if engine exhibits
misfire or black smoke at steady load. Turbocharger Inspection: Check
end play and radial clearance at 2000 hours. Replace if end play exceeds
0.003 in (0.076 mm) or radial clearance exceeds 0.030 in (0.76 mm).
Electronic Governor Calibration: Perform recalibration after any battery
disconnection or governor module replacement. Procedure requires a
frequency counter and load bank. Starter Motor Inspection: Clean
commutator and replace brushes every 1500 hours.
Cylinder Head Bolts (M16), Stage 1: 75 lb-ft (102 Nm).
Cylinder Head Bolts (M16), Stage 2: 110 lb-ft (149 Nm).
Connecting Rod Bolts (M12): 43 lb-ft (58 Nm).
Main Bearing Cap Bolts (M14): 100 lb-ft (136 Nm).
Flywheel Bolts (to crankshaft flange): 95 lb-ft (129 Nm).
Flywheel Housing Bolts (to block): 55 lb-ft (75 Nm).
Crankshaft Damper Pulley Bolt (center bolt): 130 lb-ft (176 Nm).
Camshaft Thrust Plate Bolts: 18 lb-ft (24 Nm).
Rocker Arm Shaft Bracket Bolts: 35 lb-ft (47 Nm).
Valve Cover Nuts (stud type): 7 lb-ft (10 Nm).
Injection Pump Mounting Nuts (Stanadyne pump): 22 lb-ft (30 Nm).
Injection Pump Drive Gear Bolt: 55 lb-ft (75 Nm).
Injector Hold-Down Clamp Bolts: 22 lb-ft (30 Nm).
High-Pressure Fuel Line Nuts (at pump and injector): 25 lb-ft (34 Nm).
Oil Pump Mounting Bolts: 18 lb-ft (24 Nm).
Oil Cooler Mounting Bolts: 25 lb-ft (34 Nm).
Water Pump Mounting Bolts: 30 lb-ft (41 Nm).
Thermostat Housing Bolts: 18 lb-ft (24 Nm).
Starter Motor Mounting Bolts: 45 lb-ft (61 Nm) for 12V system.
Starter Motor Mounting Bolts: 55 lb-ft (75 Nm) for 24V system.
Alternator Pivot Bolt: 40 lb-ft (54 Nm).
Alternator Adjusting Arm Bolt: 18 lb-ft (24 Nm).
Turbocharger Mounting Nuts (to exhaust manifold): 45 lb-ft (61 Nm).
Turbocharger Oil Drain Line Bolt (to block): 18 lb-ft (24 Nm).
Electronic Governor Actuator Mounting Bolts (on injection pump): 8 lb-ft
(11 Nm).
The John Deere 6068HFG20 engine is exclusively used in generator set
(genset) applications. It is not offered in mobile equipment such as
tractors or wheel loaders due to its fixed-speed governing and
non-certified emission status.
Standby Generator Sets: The engine forms the core of generator sets
rated from 150 kVA to 280 kVA (at 0.8 power factor).
John Deere Power Generation (EP series: EP200, EP225, EP250, EP275).
Generac Industrial (SD series).
Caterpillar (Olympian series rebranded with John Deere engines).
Kohler (KD series with John Deere base engines).
Telecommunications: Standby power for cellular towers and microwave
relay stations in developing countries where grid instability is common.
Healthcare: Emergency backup for rural hospitals and clinics operating
under local emission exemptions.
Agricultural: Prime power for large-scale irrigation pumping stations in
off-grid locations (e.g., cotton farms in Central Asia).
Marine: Auxiliary generator sets for small cargo vessels flagged in
non-ECA (Emission Control Area) regions, providing ship service power at
60 Hz.
____________________________________________________________________________________
| Industrial Engines Technical Specifications |
| Car Engines Technical Specifications |
| Small Engines Technical Specifications |
| Outboard Engines Technical Specifications |
