Cat 3406B Specifications
| Engine Model: Caterpillar 3406B |
| Engine Type: 4-cycle inline 6-cylinder turbocharged and aftercooled diesel |
| Total Displacement: 893 cu.in (14.6 L) |
| Rated Engine Power: 255-475 Hp (190-354 kW) at 2000 rpm |
| Fuel System Type: Mechanical unit injector |
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The Caterpillar 3406B is a critical evolution
within the 3406 series, representing the bridge between purely
mechanical engines and full electronic control. This inline
six-cylinder, 14.6-liter heavy-duty diesel engine is renowned for its
brute strength, mechanical simplicity, and formidable reputation in the
most demanding on-highway and off-road applications. The "B-Series"
incorporated significant design refinements over the initial 3406,
including improvements to the cylinder head, fuel system, and block
structure, aimed at enhancing durability and power output.
It is characterized by its mechanical unit injector fuel system and, in
later production, the optional PEEC (Programmable Electronic Engine
Control) system. The 3406B delivers a wide range of horsepower, making
it a versatile powerplant for long-haul trucking, heavy construction,
and marine propulsion, solidifying its status as a legendary workhorse
prized for its longevity and torque.
Engine Type: Inline 6-Cylinder, Four-Stroke Cycle Diesel.
Aspiration: Turbocharged and Aftercooled.
Configurations include Turbocharged (T), Turbocharged and Jacket Water
Aftercooled (TJWAC), and Turbocharged and Air-to-Air Aftercooled
(ATAAC).
Displacement: 14.6 Liters (893 cubic inches).
Bore: 137 mm (5.4 inches).
Stroke: 165 mm (6.5 inches).
Engine Power (Generator): 300-475 hp (224-354 kW).
Engine Power (Truck): 255-400 hp (190-298 kW).
Compression Ratio: 15.8:1.
Firing Order: 1-5-3-6-2-4.
Rotation (Viewed from Flywheel End): Counterclockwise.
Governor Type: Mechanical, with an optional electronic governor (PEEC)
on later models.
Emission Certification: Manufactured in configurations meeting pre-Tier
and U.S. EPA 1991 heavy-duty emissions standards.
The cylinder block is a massive, deep-skirt cast iron structure designed
for ultimate rigidity under extreme loads. It incorporates replaceable
wet-type cylinder liners. The liners are pressed into the block and
sealed at the top with a copper composition gasket under a
precision-machined flange. The lower end employs a cross-bolted main
bearing design.
Each of the seven nodular iron main bearing caps is secured by two
vertical bolts and two horizontal cross bolts that thread deep into the
block's lower skirt. This configuration provides an exceptionally stable
foundation for the crankshaft, essential for managing high horsepower
and torque outputs. The camshaft is gear-driven and rotates within
bearings machined directly into the block.
A single cast iron cylinder head is used, secured by four bolts per
cylinder. The head employs a four-valve-per-cylinder design - two intake
and two exhaust - to optimize airflow for the turbocharged-aftercooled
configuration. Valve seat inserts are hardened for extended service life
under high thermal loads.
Valve guides are replaceable. Valve actuation is via pushrods and rocker
arms; the rocker arms are shaft-mounted. Valve lash requires manual
adjustment using a screw and locknut on each rocker arm. The cylinder
head gasket is a solid copper or heavy-duty composite design.
The 3406B primarily utilizes a mechanically controlled fuel system. It
employs Caterpillar's Mechanical Unit Injector (MUI) system, where each
cylinder has a unit injector actuated by the engine's camshaft. The
injector combines the pumping element and nozzle, generating high
injection pressure mechanically.
Fuel rack setting and timing are mechanical adjustments. Later 3406B
engines offered the PEEC (Programmable Electronic Engine Control)
option, which added electronic control to the unit injectors for
improved timing and diagnostics, serving as a precursor to the full
3406E EUI system. A gear-type transfer pump supplies fuel from the tank
through primary and secondary filters.
Lubrication is provided by a high-volume gear-type oil pump driven from
the front gear train. Oil is drawn from a deep cast aluminum sump
through a pickup tube and screen. It is then forced through a full-flow,
spin-on or canister-type oil filter. A bypass valve protects the system.
Filtered oil is routed through a large, integral oil cooler before
entering the main oil gallery. From the gallery, oil is distributed to
the crankshaft main and connecting rod bearings, camshaft bearings,
turbocharger, and valve train. Piston cooling jets spray a directed,
high-volume stream of oil onto the underside of each piston, a critical
design for heat management.
Coolant circulation is managed by a gear-driven centrifugal water pump.
Coolant flows from the pump through optimized passages in the cylinder
block and cylinder head. A wax-pellet thermostat regulates engine
operating temperature.
The system incorporates an aftercooler; ATAAC models use an air-to-air
core, while TJWAC models use a jacket water aftercooler. The engine
cooling system requires a radiator or heat exchanger of substantial
capacity. A coolant conditioner filter is standard equipment to maintain
supplemental additive levels and protect against liner cavitation.
Starting System: 12-volt, 24-volt, or 32-volt electric starting motor.
Air starting systems are a frequent and reliable option for vocational
and industrial applications. Charging System: A heavy-duty brushless
alternator, with outputs from 105 to 145 amperes.
Air Intake System: A dry-type, two-stage air cleaner system with a
primary safety element and a main filter, equipped with a restriction
indicator. Exhaust System: A divided-entry cast iron exhaust manifold
pairs cylinders to optimize turbocharger response. A wastegate regulates
boost pressure.
Electronic Control (PEEC): The optional PEEC system provided an
electronic control module for governing and basic diagnostics,
representing an intermediate step in Caterpillar's transition to full
electronic management.
Dimensions reflect the engine's large displacement and heavy-duty
construction. For a standard on-highway truck configuration, approximate
length is 2972 mm (117.0 inches), width is 991 mm (39.0 inches), and
height is 1473 mm (58.0 inches). The net dry engine weight, excluding
fluids but including standard accessories like a heavy-duty alternator
and air compressor, ranges from 1179 kg to 1270 kg (2600 lb to 2800 lb).
This weight is indicative of the engine's robust internal components and
construction.
Engine Oil Grade: Use Caterpillar Diesel Engine Oil (DEO) or an
equivalent oil meeting API CD, CE, or CF-4 specifications. SAE 15W-40 is
common for general operation. Oil Change Interval: Dictated by service
severity. In on-highway service, intervals of 15,000 to 25,000 miles
(24,000-40,000 km) were common. Severe off-road duty often followed
250-hour intervals. Oil analysis is a recommended practice. Oil System
Capacity: Total refill capacity, including filter change, is
approximately 37.9 Liters (40 US quarts).
Cooling System Capacity: Total cooling system capacity is approximately
32.2 Liters (34 US quarts) for the engine itself; total system capacity
with radiator is larger, around 68.1 Liters (18 US gallons). Engine
Coolant: Use a 50/50 mixture of ethylene glycol antifreeze and
demineralized water. Maintain proper concentration of supplemental
coolant additive (SCA) via a coolant filter to prevent wet liner
cavitation.
Fuel Filter: Replace primary and secondary fuel filter elements every
15,000 miles (24,000 km) or 500 hours. Air Filter: Service or replace
based on restriction gauge indication. The primary safety element is
serviceable. Valve Lash Adjustment (Cold): Intake: 0.38 mm (0.015 in).
Exhaust: 0.76 mm (0.030 in). Adjust at initial break-in and every
subsequent 1000 hours of operation.
Cylinder Head Bolts: Tighten in a specific three-step sequence. Final
torque: 270 Nm (200 lb-ft).
Main Bearing Cap Bolts (Vertical): 340 Nm (250 lb-ft).
Main Bearing Cap Cross Bolts: 160 Nm (118 lb-ft).
Connecting Rod Cap Bolts: 200 Nm (148 lb-ft) plus an additional
60-degree turn.
Flywheel Housing-to-Block Bolts: 160 Nm (118 lb-ft).
Flywheel-to-Crankshaft Bolts: 285 Nm (210 lb-ft).
Unit Injector Clamp Bolt: 50 Nm (37 lb-ft).
Oil Pan Bolts: 55 Nm (41 lb-ft).
Oil Filter Cap or Cartridge: For spin-on filters, hand-tighten plus
three-quarters turn. For canister types, tighten cap to 75 Nm (55
lb-ft).
The Caterpillar 3406B engine was a dominant
force in heavy-duty sectors:
On-Highway Trucks: The premier powertrain for late 1980s and early 1990s
long-haul tractors from Peterbilt (359, 379), Kenworth (W900, T600),
Freightliner (FLC 120), and Navistar International (9300).
Construction/Mining: Powered Caterpillar 769D, 773B Rock Trucks; 988B,
992C Wheel Loaders; D8L, D9L Track-Type Tractors; and large hydraulic
excavators. Marine Propulsion: Used in larger commercial fishing
vessels, tugboats, coast guard vessels, and small ferries as a
high-horsepower propulsion engine.
Power Generation: A prime mover for large stationary generator sets in
the 300-600 kW range. Oil and Gas: Powered large frac pumps, cement
pumps, and drilling rig mud pumps. Logging: The standard power for large
off-highway log skidders and forwarders. Specialty: Powered heavy-duty
fire apparatus, snow removal vehicles, and airport crash trucks.
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