Nissan TB42S Specifications
| Engine Model: Nissan TB42S |
| Engine Type: 4-cycle inline 6-cylinder OHV 12-valve liquid-cooled gasoline |
| Total Displacement: 254.4 cu.in (4.16 L) |
| Rated Engine Power: 168 Hp (125 kW) at 4200 rpm |
| Fuel System Type: Two-barrel down-draft carburetor |
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The Nissan TB42S is a 4.2-liter inline six-cylinder
gasoline engine produced by Nissan from 1987 through the late 1990s,
representing the carbureted variant within the TB engine family. Developed as a
heavy-duty powerplant for the Nissan Patrol off-road vehicle and Safari series,
this engine was engineered for extreme durability and operational simplicity in
demanding environments.
The TB42S shares its fundamental architecture with the legendary TD42 diesel
engine, including the same cast iron block and square bore-stroke dimensions,
establishing a reputation for robustness that has made it a preferred choice for
remote-area operation where access to sophisticated diagnostic equipment is
limited.
The engine’s design philosophy prioritizes mechanical simplicity and low-end
torque delivery over peak power output. The 4,169 cc displacement, achieved
through a 96.0 mm bore and 96.0 mm stroke, produces a broad torque plateau
suited to the heavy-duty off-road and commercial applications for which the
TB42S was intended. The overhead valve (OHV) valvetrain with pushrods and two
valves per cylinder reflects this emphasis on simplicity, eliminating the
complexity of overhead camshaft mechanisms while providing adequate volumetric
efficiency for the engine’s intended duty cycle.
Power output is rated at 125 kW (168 hp) at 4,200 rpm with 320 Nm (236 lb-ft) of
torque at 2,800 rpm, delivered through a two-barrel down-draft carburetor. The
compression ratio of 8.3:1 allows operation on lower-octane fuels without
detonation, a critical consideration for markets where fuel quality varies. The
chain-driven timing system and the absence of complex electronic controls
contribute to the engine’s reputation for field-serviceability.
The TB42S remained in production for the Y60 Patrol throughout its lifecycle and
continued into early Y61 production for specific markets, including the Middle
East, where the carbureted configuration was retained for its simplicity and
reliability.
The TB42S operates on a four-stroke gasoline cycle with carbureted fuel
delivery. The engine utilizes an inline six-cylinder configuration with an
overhead valve (OHV) valvetrain.
Engine Type: Inline-6, water-cooled, 4-stroke, naturally aspirated gasoline.
Displacement: 4,169 cc (254 cu.in).
Bore: 96.0 mm (3.78 in).
Stroke: 96.0 mm (3.78 in).
Compression Ratio: 8.3:1.
Firing Order: 1-5-3-6-2-4.
Idle Speed: 650-700 rpm, adjustable via carburetor idle mixture and speed
screws.
Maximum Engine Speed: 4,800 rpm governed.
Redline at 4,500 rpm for sustained operation.
Maximum Power: 125 kW (168 hp) @ 4,200 rpm.
Maximum Torque: 320 Nm (236 lb-ft) @ 2,800 rpm
Aspiration: Naturally aspirated.
Fuel System: Two-barrel down-draft carburetor with mechanical accelerator pump
and automatic choke.
Ignition System: Electronic ignition (later models) or breaker-point ignition
(early models) with mechanical centrifugal advance and vacuum advance.
The cylinder block is constructed from high-strength
cast iron with a deep-skirt design that extends below the crankshaft centerline.
This robust architecture, shared with the TD42 diesel engine, provides
exceptional rigidity under the high cylinder pressures encountered during
sustained low-speed operation and heavy towing applications.
The block features siamesed cylinder bores - adjacent cylinders share common
walls - reducing overall engine length while maximizing structural integrity
between cylinders. Cylinder bores are cast directly into the block with no
replaceable liners. Each bore is induction-hardened to provide a durable wear
surface for the piston rings, with the hardening process creating a martensitic
layer approximately 1.2 mm (0.047 in) deep.
Main bearing caps are manufactured from nodular cast iron and are secured with
two bolts each. The main bearing structure incorporates reinforcing ribs
extending from the main bearing bulkheads to the lower crankcase area, providing
additional support for the crankshaft under high-load conditions.
Crankshaft: Forged steel with seven main bearings, fully counter-weighted with
twelve counterweights. The crankshaft features induction-hardened bearing
surfaces and incorporates a torsional vibration damper at the front end.
Main Bearing Journal Diameter: 70.0 mm (2.76 in).
Connecting Rod Journal Diameter: 56.0 mm (2.20 in).
Connecting Rods: Forged steel, machined mating surfaces with locating dowels.
Piston Material: Cast aluminum alloy with a low-friction skirt coating and
steel-strut reinforcement to control thermal expansion. Piston Cooling: Oil
splash from the connecting rod bearings provides piston cooling; no dedicated
oil jets are present in this naturally aspirated engine.
The cylinder head is a single-piece cast aluminum alloy
construction spanning all six cylinders. This material choice reduces overall
engine weight while providing adequate thermal conductivity for the naturally
aspirated gasoline configuration. The head incorporates a cross-flow port
arrangement with intake ports on the right side and exhaust ports on the left
side of the engine.
Valvetrain: Overhead valve (OHV) with pushrods and rocker arms, operating two
valves per cylinder, totaling 12 valves. A single camshaft located in the
cylinder block actuates the valves through hydraulic lifters, pushrods, and
shaft-mounted rocker arms. The hydraulic lifters automatically maintain zero
valve clearance throughout the engine’s service life.
Intake Valve Diameter: 45.0 mm (1.77 in).
Exhaust Valve Diameter: 40.0 mm (1.57 in).
Valve Lift (Intake): 10.5 mm (0.413 in).
Valve Lift (Exhaust): 10.0 mm (0.394 in).
Valve Seat Material: Sintered steel alloy with induction-hardened contact
surfaces.
Valve Spring Material: High-tensile steel with a conventional cylindrical
design.
Camshaft: Cast iron camshaft with six bearing journals, driven by the timing
chain. The camshaft incorporates lobes ground to provide the valve timing
characteristics optimized for low-end torque delivery.
Camshaft Drive: Silent-type Morse timing chain with an automatic hydraulic
tensioner. The chain drives from a sprocket on the crankshaft to a sprocket on
the camshaft. The chain system is designed for the engine’s service life under
normal operating conditions.
The fuel system utilizes a two-barrel down-draft
carburetor manufactured by Hitachi or Nikki depending on production date and
market. This carburetor configuration provides separate primary and secondary
barrels, with the primary barrel handling idle and light-load operation and the
secondary barrel opening under heavy load to supply additional air-fuel mixture.
Carburetor Type: Two-barrel down-draft with mechanical secondary actuation,
accelerator pump, and automatic choke. The automatic choke utilizes a bimetal
coil and electric heater or coolant-sensing element depending on application.
Fuel Pump: Mechanical diaphragm-type pump mounted on the cylinder block, driven
by an eccentric lobe on the camshaft. The pump delivers fuel at 20 - 30 kPa (3 -
4 psi) to the carburetor. Fuel Filter: In-line disposable filter mounted between
the fuel pump and carburetor.
Intake Manifold: Cast iron manifold with a single-plane design feeding all six
cylinders. The manifold incorporates coolant passages for intake charge heating
during warm-up to improve fuel vaporization.
Throttle Linkage: Mechanical cable-actuated throttle with integrated idle speed
adjustment and throttle position sensor on later electronic-ignition variants.
Fuel Requirement: Minimum octane rating of 85 RON (regular unleaded) for
operation in standard conditions; 87 RON recommended for sustained high-load
operation.
The lubrication system is a fully pressurized wet-sump
design with a gear-type oil pump mounted on the front of the engine. The pump is
driven directly by the crankshaft and incorporates a pressure relief valve to
maintain consistent oil pressure across the operating range. Oil Pump Type:
Gear-type pump with integrated pressure relief valve set at 450 kPa (65 psi).
Recommended Oil Viscosity: 15W-40, 20W-50, or 10W-30 conventional oil meeting
API SF, SG, SH, or higher specifications. High-zinc formulations are recommended
for flat-tappet valvetrain protection.
Oil Capacity (including filter): 7.5 liters (7.9 qt).
Oil Pressure (at idle, warm): 70 - 150 kPa (10 - 22 psi).
Oil Pressure (at 2,500 rpm, warm): 300 - 400 kPa (44 - 58 psi).
Oil Filter Type: Spin-on full-flow filter with integral bypass valve and
anti-drainback valve. Oil Cooler: Not equipped on standard TB42S variants;
select heavy-duty or hot-climate export models incorporate a coolant-to-oil heat
exchanger. Oil Pan: Stamped steel with integrated baffling and a shallow-sump
configuration for front axle clearance in Patrol applications.
The cooling system is a pressurized, thermostatically
controlled circuit utilizing a belt-driven centrifugal water pump. The system is
designed to manage thermal loads under sustained low-speed operation and heavy
towing conditions.
Water Pump Type: Centrifugal with a mechanical seal, mounted to the front of the
cylinder block and driven by the accessory drive belt. Coolant Type:
Ethylene-glycol based antifreeze meeting Nissan specification, phosphate and
silicate-free formulation.
Coolant Capacity (engine and radiator): 11.0-12.0 liters (11.6-12.7 qt)
depending on radiator configuration. Thermostat: Wax-type thermostat with an
opening temperature of 82 °C (180 °F) and a full-open temperature of 95 °C (203
°F).
Radiator: Cross-flow copper-brass or aluminum radiator with a high fin density,
sized for tropical climate operation in Patrol applications. Cooling Fan:
Engine-driven viscous clutch fan with a thermostatic bimetal element that
engages fan operation based on radiator air temperature.
Timing Drive: Silent-type Morse timing chain with an
automatic hydraulic tensioner. The tensioner utilizes engine oil pressure to
maintain chain tension and incorporates a mechanical ratchet to prevent slack
during engine start-up before oil pressure builds. The chain guides are
manufactured from nylon-faced aluminum.
Accessory Drive: Multiple V-belts driving the water pump, alternator, power
steering pump, and air conditioning compressor. Belt tension is adjusted
manually at each accessory.
Ignition System: Early variants utilize a breaker-point distributor with
mechanical centrifugal advance and vacuum advance. Later variants employ an
electronic ignition system with a magnetic pickup distributor, ignition control
module, and vacuum advance. The distributor is driven by a gear on the camshaft
and incorporates the oil pump drive at its base. Spark Plugs: NGK BPR5ES or
equivalent. Spark Plug Gap: 0.8-0.9 mm (0.031-0.035 in). Alternator: 60-90 amp
depending on vehicle equipment specification. Starter Motor: Reduction-gear type
with 2.0 kW output.
Exhaust System: Cast iron exhaust manifold with a single outlet. The exhaust
system incorporates a single catalytic converter on markets where emissions
regulations required, though many export variants operated without catalytic
converter equipment.
Overall Length: 900 mm (35.4 in).
Overall Width: 680 mm (26.8 in).
Overall Height: 790 mm (31.1 in).
Dry Weight (complete engine): 295 kg (650 lb).
Engine Oil and Filter Change: 5,000 km (3,000 mi) or 6
months for conventional oil; 10,000 km (6,000 mi) for semi-synthetic or fully
synthetic oil. Timing Chain: Chain inspection is recommended if abnormal noise
or timing correlation issues are present. Valve Clearance: Hydraulic lifters
eliminate the need for valve clearance inspection or adjustment throughout the
engine’s service life.
Fuel Filter Replacement: 20,000 km (12,000 mi) or 2 years. Carburetor Service:
Air filter replacement at 20,000 km (12,000 mi); carburetor cleaning and
adjustment as required based on driveability symptoms. Engine Air Filter
Element: Replace every 20,000 km (12,000 mi) or when visibly contaminated; more
frequent replacement required in dusty environments. Coolant Replacement: 40,000
km (24,000 mi) or 2 years.
Drive Belt Inspection: Every 5,000 km (3,000 mi) for cracks, fraying, glazing,
and proper tension. Drive Belt Replacement: 40,000 km (24,000 mi) or 2 years.
Spark Plug Replacement: 20,000 km (12,000 mi) for conventional plugs; 40,000 km
(24,000 mi) for platinum equivalents. Distributor Cap and Rotor: Inspect every
20,000 km (12,000 mi); replace if carbon tracking or corrosion is present.
Cylinder Head Bolts, Step 1: 30 Nm (22 lb-ft)
Cylinder Head Bolts, Step 2: 60 Nm (44 lb-ft)
Main Bearing Cap Bolts: 90 Nm (66 lb-ft)
Connecting Rod Cap Bolts: 55 Nm (41 lb-ft)
Camshaft Bearing Caps: 25 Nm (18 lb-ft)
Camshaft Thrust Plate: 15 Nm (11 lb-ft)
Timing Chain Tensioner: 25 Nm (18 lb-ft)
Intake Manifold to Cylinder Head: 35 Nm (26 lb-ft)
Exhaust Manifold to Cylinder Head: 40 Nm (30 lb-ft)
Rocker Arm Shaft Mounting Bolts: 35 Nm (26 lb-ft)
Pushrod Cover Bolts: 8 Nm (6 lb-ft)
Oil Pan Bolts: 15 Nm (11 lb-ft)
Valve Cover Bolts: 8 Nm (6 lb-ft)
Spark Plugs: 20 Nm (15 lb-ft)
Crankshaft Pulley Bolt: 200 Nm (148 lb-ft)
Flywheel / Flexplate Bolts: 100 Nm (74 lb-ft)
Engine Mount Brackets to Block: 50 Nm (37 lb-ft)
Distributor Clamp Bolt: 20 Nm (15 lb-ft)
Carburetor Mounting Nuts: 20 Nm (15 lb-ft)
The TB42S engine was installed across a range of Nissan
heavy-duty passenger and commercial vehicle platforms from 1987 through the late
1990s, with select applications continuing into the early 2000s.
Nissan Patrol (GQ / Y60, 1987 - 1997): The TB42S served as the primary gasoline
engine for the GQ Patrol across global markets, including Australia, the Middle
East, Africa, and South America. The engine was offered in both wagon and
cab-chassis configurations, with the carbureted setup preferred in markets where
fuel quality varied or where electronic fuel injection systems were considered
less serviceable in remote areas. The Patrol application utilized a specific oil
pan configuration with clearance for the front axle and steering linkage.
Nissan Safari (Y60, 1987 - 1997): The Japanese domestic market Safari received
the TB42S as the gasoline engine option alongside the TD42 diesel. The Safari
application included additional emissions control equipment to meet Japanese
market requirements while retaining the carbureted induction system.
Ford Maverick (Australia, 1988 - 1994): The Ford-badged version of the Nissan
Patrol, sold in Australia as the Ford Maverick, utilized the TB42S as the
standard gasoline engine. The Maverick variant was mechanically identical to the
Patrol GQ, with no modifications to the engine specification.
Nissan Civilian (W40 / W41 bus, 1988 - 1999): The TB42S was installed in the
Nissan Civilian light bus and minibus series, where the engine’s torque
characteristics suited the stop-start demands of urban passenger transport. Bus
applications included a rear-engine configuration with modifications to the
cooling system and accessory drive layout.
Nissan Patrol (GU / Y61, 1997 - 2000): Early production of the Y61 Patrol in
select markets, including the Middle East, retained the TB42S carbureted engine
before transitioning to the fuel-injected TB42E variant. These Y61 applications
utilized an updated engine mounting system and cooling package adapted to the
revised chassis architecture while retaining the TB42S’s fundamental
specifications.
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