John Deere 6068T Specifications
| Engine Model: John Deere 6068T |
| Engine Type: 4-cycle inline 6-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 415 cu.in (6.8 L) |
| Rated Engine Power: 148-208 Hp (111-155 kW) at 2400 rpm |
| Fuel System Type: Direct fuel injection |
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The John Deere 6068T is a 6.8-liter,
six-cylinder, turbocharged diesel engine engineered for high-performance
industrial, agricultural, and power generation applications. This
four-stroke, direct injection power plant is part of John Deere's
PowerTech family, designed to deliver a broad range of power outputs
with strong torque characteristics. The engine incorporates advanced
features such as a four-valve cylinder head, an electronically
controlled unit pump fuel system, and air-to-air aftercooling to achieve
efficiency and power density.
Its construction emphasizes durability through the use of a
high-strength cylinder block, wet sleeve liners, and a gear-driven front
end. The 6068T is configurable for various emissions compliance levels
and is recognized for its adaptability across a wide spectrum of
demanding equipment, from heavy tractors to standby generators and
construction machinery.
Engine Type: 6-cylinder, inline, 4-stroke cycle, vertical,
liquid-cooled, turbocharged and aftercooled diesel.
Combustion System: Direct injection, four-valve.
Aspiration: Turbocharged with air-to-air aftercooler (charge-air
cooler).
Rotation: Counterclockwise when viewed from the flywheel end.
Firing Order: 1-5-3-6-2-4.
Bore: 106.0 mm (4.17 inches).
Stroke: 127.0 mm (5.00 inches).
Displacement: 6.8 liters (415 cubic inches).
Compression Ratio: 17.0:1.
Governor Type: Electronic, controlled by the Engine Control Unit (ECU)
for most configurations; mechanical variants exist.
Power Output Range: 110.5 to 155 kW (148 to 208 Hp) at rated speeds,
which vary from 2200 to 2500 crankshaft rpm depending on the
application.
Peak Torque Output: 614 to 793 Nm (453 to 585 lb-ft) occurring between
1400 and 1500 crankshaft rpm. High Idle Speed: Electronically or
mechanically governed, application-specific.
Low Idle Speed: 750 to 800 crankshaft rpm.
Fuel Shutoff: Electronic solenoid or mechanical, dependent on
configuration.
Dry Weight (base engine): 569 to 678 kg (1254 to 1495 lbs), varying with
accessories and configuration.
The cylinder block is a single-piece, high-strength gray iron casting
with a deep-skirt design. This construction provides exceptional
rigidity, minimizing distortion and controlling noise and vibration. The
block incorporates replaceable, press-fit wet-type cylinder sleeves.
These sleeves are manufactured from centrifugally cast alloy iron,
offering superior wear resistance and allowing efficient heat transfer
directly to the surrounding coolant.
The crankshaft is supported by seven main bearings with steel-backed,
aluminum alloy bearing inserts. Main bearing caps are nodular iron and
are secured with two vertical bolts each, plus two lateral cross-bolts
per cap on many configurations, creating an extremely rigid lower block
structure. The block houses the camshaft and features extensive internal
oil and coolant galleries.
The cylinder head is a single-piece, cast iron component. It employs a
crossflow design with four valves per cylinder (two intake, two
exhaust). This four-valve layout optimizes airflow for improved
combustion efficiency, power output, and thermal management. Valve seats
are induction-hardened inserts, and valve guides are replaceable. Intake
and exhaust valves are manufactured from heat-resistant steel alloys.
Valve actuation uses individual, shaft-mounted rocker arms. Valve lash
is adjusted manually via screw-type adjusters on the rocker arms,
requiring periodic maintenance. The camshaft, located in the cylinder
block, operates the valves through solid lifters and pushrods. A
multilayer steel head gasket seals the combustion chambers and fluid
passages.
The fuel system is an electronically controlled, unit pump direct
injection system for most configurations. A camshaft-driven, gear-type
transfer pump supplies fuel from the tank through a primary filter/water
separator and a secondary fuel filter. The system's core comprises six
individual electronic unit pumps (EUPs), each mounted in the cylinder
block and actuated by its own camshaft lobe.
Each EUP incorporates a high-pressure solenoid valve controlled by the
Engine Control Unit (ECU). The ECU determines precise injection timing
and duration based on inputs from multiple sensors. High-pressure steel
lines connect each EUP to its corresponding injector. The injectors are
pencil-type, multi-hole units. Some earlier or specific industrial
variants may utilize a mechanical in-line injection pump. Fuel shutoff
is managed by an ECU-controlled solenoid or a mechanical actuator.
The lubrication system is a full-pressure, gear-driven design. A tandem
gear-type oil pump, driven from the front gear train, provides oil flow.
The pump may incorporate separate sections for engine lubrication and
hydraulic system supply in certain applications. For engine lubrication,
oil is drawn from the oil pan through a pickup tube and screen.
Pressurized oil is forced through a full-flow, spin-on oil filter.
Filtered oil is distributed through main galleries to the crankshaft
main bearings, connecting rod bearings, camshaft bearings, and the valve
rocker shaft. A dedicated piston cooling jet sprays oil onto the
underside of each piston crown. The turbocharger center bearing receives
oil via a dedicated feed line. A pressure relief valve maintains system
pressure. Total engine oil system capacity is 19.0 liters (20.1 U.S.
quarts) with filter. Oil meeting John Deere performance standard JDM J27
or API CH-4/CG-4 and later is required.
The cooling system is a pressurized, liquid-cooled design. A centrifugal
water pump, gear-driven from the front of the engine, circulates
coolant. Coolant flow is directed first through the cylinder block, then
into the cylinder head, and through the oil cooler and aftercooler core
before returning to the radiator. A wax-pellet-type thermostat regulates
coolant temperature.
System pressure is maintained by a radiator pressure cap, commonly rated
for 100 kPa (15 psi). Airflow across the radiator and aftercooler is
provided by a belt-driven or hydraulic fan. The system incorporates a
coolant degas bottle for air separation and level maintenance. Total
coolant capacity is 28.0 liters (29.6 U.S. quarts). A 50/50 mixture of
ethylene-glycol antifreeze meeting John Deere specification JDM J71C and
water is required.
Air Management System: The system includes a wastegated turbocharger and
an air-to-air aftercooler. The aftercooler reduces the temperature of
the compressed intake air, significantly increasing charge density for
improved combustion efficiency and power.
Electrical and Electronic System: The engine is managed by a dedicated
Engine Control Unit (ECU) on electronically controlled models. Sensors
monitor crankshaft position, camshaft position, coolant temperature, oil
pressure, intake manifold pressure and temperature, and fuel pressure.
The system includes a 12V or 24V electric starting motor and a
corresponding alternator. An intake air heater grid assists in
cold-weather starting.
Exhaust System: Exhaust gases drive the turbocharger turbine before
exiting through the exhaust manifold and piping. Specific configurations
may include an exhaust gas recirculation (EGR) cooler for emissions
compliance. Flywheel and Housing: A SAE standard flywheel housing is
used. The flywheel is a machined cast iron or steel component,
application-specific.
Overall Length (Front of damper to flywheel housing face): 1210 mm (47.6
inches).
Overall Width (Maximum at valve cover/intake manifold): 775 mm (30.5
inches).
Overall Height (Top of valve cover to oil pan rail): 1105 mm (43.5
inches).
Dry Weight (Base engine, less coolant and oil): Ranges from 569 kg (1254
lbs) for a basic configuration to 678 kg (1495 lbs) for a fully dressed
unit with accessories.
Engine Oil Change Interval: 500 service hours or annually. Severe
service conditions (extreme dust, high idle, frequent cold operation)
mandate 250-hour intervals. Oil Filter Change: Replace with every oil
change.
Fuel Filter Service: Drain water from primary separator daily; replace
primary filter cartridge every 500 hours and secondary filter every 1000
service hours. Air Filter Element Service: Replace element based on
restriction gauge indication; inspect housing every 250 service hours.
Coolant Change Interval: 3000 service hours or 3 years.
Valve Lash Adjustment (Cold Engine Setting): Intake valve: 0.35 mm
(0.014 inches); Exhaust valve: 0.46 mm (0.018 inches). Inspect and
adjust every 1000 service hours. Aftercooler Core Service: Inspect and
clean the external fins of the aftercooler core every 1000 service
hours.
Fuel Injection System Service: Diagnostic and calibration procedures for
electronic unit pumps require specialized electronic service tools (John
Deere Service ADVISOR). Fan Drive Belt Tension: Adjust to provide 10 to
13 mm (0.4 to 0.5 inches) of deflection at the belt's longest span under
moderate thumb pressure.
Cylinder Head Bolts: Torque in specified sequence to 160 Nm (118 lb-ft),
then final angle tighten an additional 90 deg.
Main Bearing Cap Bolts (Vertical): 190 Nm (140 lb-ft). Cross-bolt torque
is application-specific.
Connecting Rod Cap Nuts: 115 Nm (85 lb-ft), then final tighten an
additional 60-degree turn.
Flywheel to Crankshaft Bolts: 160 Nm (118 lb-ft).
Rocker Arm Shaft Support Bolts: 55 Nm (41 lb-ft).
Fuel Injection Line Nuts (at unit pump and injector): 25 Nm (18 lb-ft).
Oil Pan Bolts: 24 Nm (18 lb-ft).
Turbocharger Mounting Nuts: 35 Nm (26 lb-ft).
The John Deere 6068T engine is a versatile power source for heavy-duty
mobile and stationary equipment. In agriculture, it powers large
tractors, combines, forage harvesters, and self-propelled sprayers.
Within construction machinery, it is found in wheel loaders, excavators,
skid-steer loaders, and asphalt pavers. For industrial use, it serves as
a prime mover for standby and prime power generator sets, as well as in
pump and compressor packages.
The engine's power range and configurability also make it suitable for
certain marine propulsion and auxiliary power applications. Specific
machine models vary widely by original equipment manufacturer, but the
engine is a core component within John Deere's own equipment lines and
is supplied to numerous other OEMs across these industries.
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