International C152 Specifications
| Engine Model: International Harvester C152 |
| Engine Type: 4-stroke in-line 4-cylinder liquid-cooled gasoline |
| Total Displacement: 152.1 cu.in (2.5 L) |
| Rated Engine Power: 26 Hp (19.5 kW) at 1650 rpm |
| Fuel System Type: Updraft carburetor |
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The International C152 is a 2.5-liter,
4-cylinder inline gasoline engine produced by International Harvester
(IH) from 1939 into the early 1950s. This powerplant is most famous as
the original engine for the Farmall H tractor, one of the most
successful and widely produced tractors in agricultural history. The
designation "C" refers to the overhead valve (OHV) configuration,
distinguishing it from the earlier "F" series flathead engines. Beyond
the Farmall H, the C-152 also served as the power unit for the W-4
standard tractor, the I-4 industrial tractor, and various stationary
power units.
The C-152 was engineered for longevity, simplicity, and high-torque
operation at low engine speeds. Its design reflects the agricultural
needs of the mid-20th century: robust construction, ease of maintenance
in field conditions, and the ability to operate on low-octane fuels. The
engine features a replaceable wet-sleeve cylinder design, a
three-main-bearing crankshaft, and a mechanical governor for maintaining
consistent engine speed under varying loads.
While modest by modern power standards, the C152 provided reliable
service for decades, with many examples still operating today. The
engine's reputation for durability and rebuildability has made it a
favorite among collectors and restorers of vintage International
Harvester equipment.
Engine Type: 4-cycle, in-line, 4-cylinder gasoline.
Aspiration: Naturally aspirated.
Displacement: 152.1 cu.in (2.5 L).
Bore: 85.7 mm (3.375 in).
Stroke: 108.0 mm (4.250 in).
Compression Ratio: 5.9:1 (designed for standard low-octane fuels of the
era).
Firing Order: 1-3-4-2.
Gross Power (flywheel): 19.4 kW (26 hp) at rated speed.
Belt or PTO Power: 17.9 kW to 20.1 kW (24-27 hp).
Drawbar Power: 14.2 kW to 17.9 kW (19-24 hp).
Rated Engine Speed: 1,650 rpm.
Maximum Torque: 142-149 Nm (105-110 lb-ft) achieved at low engine speed.
Governor: Mechanical flyweight type, gear-driven from the camshaft.
Governed Speed Range: 750 to 1,650 rpm.
The cylinder block of the C-152 is constructed from cast iron, providing
a rigid foundation for the rotating assembly and a durable operating
life in dusty agricultural environments. The block features a deep-skirt
design, where the cylinder walls extend below the crankshaft centerline,
adding structural support. A defining characteristic of this engine is
its replaceable wet-sleeve cylinder design.
Each cylinder uses an individual cast-iron sleeve that contacts the
engine coolant directly. This design allows the engine to be fully
rebuilt without machining the block itself; worn sleeves are pressed out
and replaced with new ones. The wet-sleeve configuration also provides
excellent heat transfer from the cylinder walls to the coolant, a
critical advantage for an engine designed to operate at sustained full
load for hours.
The block houses a three-bearing crankshaft, supported by three main
bearing journals. This configuration is simpler than a five-main-bearing
design but was adequate for the engine's low-rpm, high-torque operating
range. The crankcase features a large side cover for access to the
connecting rod caps and internal components, simplifying routine
maintenance and bearing inspection. A mechanical fuel pump is mounted on
the left side of the block, driven by an eccentric lobe on the camshaft.
The cylinder head is a separate cast-iron component bolted to the
cylinder block using a flat metal or composition head gasket. It employs
an overhead valve (OHV) configuration with pushrods and rocker arms, an
advanced design for the late 1930s compared to the flathead engines
common to that era. The OHV layout positions the combustion chamber
directly over the pistons, improving volumetric efficiency and allowing
for a higher compression ratio than flathead designs.
Valvetrain Configuration: Overhead valve, mechanical lifters, pushrods,
rocker arms.
Valves per Cylinder: 2 (one intake, one exhaust).
Valve Arrangement: In-line, valves positioned in a row along the
cylinder head.
Intake Valve Diameter: 34.9 mm (1.375 in).
Exhaust Valve Diameter: 31.8 mm (1.250 in).
Valve Lifter Type: Solid (mechanical) tappets.
Valve Seat Material: Cast iron integrated into the cylinder head.
The combustion chamber is a shallow-bowl design, with the valves
positioned vertically in line with the cylinder bores. The spark plug is
located between the two valves. Valve lash adjustment requires periodic
maintenance, performed by turning an adjusting screw on the rocker arm
while the engine is cold. The exhaust valve seats are induction-hardened
for extended life under continuous high-load operation.
The fuel system on the C152 consists of an updraft carburetor, a
mechanical fuel pump, and a mechanical governor. The updraft carburetor
(manufactured by IHC or Zenith depending on production year) draws air
upward through the carburetor body into the intake manifold. This design
positions the carburetor lower than the intake manifold, reducing the
risk of fuel leakage onto the hot engine. The carburetor includes a
float-type fuel bowl, an idle circuit, a main metering circuit, and a
manual choke for cold starting.
The mechanical governor is the most critical component of the fuel
system. Driven by a gear from the camshaft, the governor uses flyweights
and a thrust bearing to sense engine speed. As engine load increases and
speed drops, the governor opens the carburetor throttle plate to
maintain the selected rpm.
Conversely, when load decreases and speed rises, the governor closes the
throttle. This system maintains the engine speed within a narrow range
regardless of load variation, essential for consistent drawbar
performance. The operator sets the desired speed using a throttle lever,
and the governor maintains that speed automatically.
Carburetor Type: Updraft, single-barrel.
Carburetor Brands: IHC or Zenith.
Fuel Pump Type: Mechanical diaphragm, camshaft-driven.
Fuel Octane Requirement: 55-60 octane (low-octane fuel of the era).
Fuel Tank Capacity (Farmall H tractor): 60.6 L (16 U.S. gallons).
The lubrication system is a gear-driven, full-pressure system delivering
oil to all critical rotating components. A gear-type oil pump is mounted
inside the oil pan and driven by a shaft from the distributor drive
gear. The pump draws oil through a submerged, wire-mesh screen and
forces it through a full-flow oil filter (on later models) before
distributing it to the main bearings, connecting rod bearings, camshaft
bearings, and valve train.
Oil Capacity (including filter): 5.7 L (6.0 U.S. quarts).
Oil Pressure at Idle (warm): 1.0 bar (15 psi).
Oil Pressure at Rated Speed (warm): 2.1 to 2.8 bar (30-40 psi).
Oil Pump Type: Gear-type.
Oil Filter Type (early versions): Bbypass filter or no filter.
Oil Filter Type (later versions): Full-flow, replaceable cartridge.
Recommended Oil Viscosity: SAE 30 or 10W-30.
Oil Pan Capacity: 4.7 L (5.0 U.S. quarts) without filter change.
Oil is delivered to the rocker arm assembly through an external oil line
running from the cylinder block to the cylinder head. The connecting
rods are lubricated via drilled passages from the crankshaft journals. A
breather tube or oil filler cap with a mesh filter allows crankcase
ventilation, preventing pressure buildup from blow-by gases.
The cooling system is a pump-assisted, thermosiphon design incorporating
a centrifugal water pump for forced circulation. Coolant is drawn from
the bottom of the radiator, circulated through the cylinder block and
cylinder head, and returned to the top of the radiator. The replaceable
wet-sleeve design allows coolant to contact the outer surfaces of the
cylinder sleeves directly, providing superior heat removal from the
combustion chambers.
Coolant Capacity: 12.3 L (13.0 U.S. quarts).
Coolant Pump Type: Centrifugal, belt-driven from the crankshaft.
Thermostat Opening Temperature: 71°C (160°F).
Radiator Type: Tube-and-fin, vertical flow (early models) or cross-flow
(later models).
Fan Type: Four-blade, belt-driven, mounted to the water pump pulley.
System Pressure: Non-pressurized (open vented system) on early models;
later models used a low-pressure radiator cap (approximately 0.2 bar or
3 psi).
The cooling system lacks a coolant recovery bottle on early models;
overflowing coolant is discharged onto the ground. The operator must
check coolant level before each use. A thermostatically controlled
shutters or radiator curtain was available as an option for cold-weather
operation, allowing the operator to restrict airflow through the
radiator to maintain operating temperature.
| Intake and Exhaust Systems |
Exhaust System: Single exhaust manifold, side-mounted, with a vertical
muffler and rain cap.
Air Intake System: Dry-type air cleaner with an oil-bath pre-cleaner on
agricultural applications. The oil-bath pre-cleaner uses oil to capture
heavy dust particles before air passes through the main filter element.
| Ignition and Electrical System |
Ignition System: Battery and coil system using a distributor. Original
equipment was 6-volt with a positive ground electrical system. The
distributor is driven by a gear from the camshaft, housing both the
mechanical advance mechanism and the contact breaker points. The firing
order is 1-3-4-2. The system includes a manual spark advance lever on
early models, replaced by an automatic centrifugal advance on later
production.
Electrical System (original): 6-volt, positive ground, with a generator
(not an alternator) and a voltage regulator. The starting motor is a
heavy-duty series-wound unit.
Electrical System (common conversion): Many surviving C-152 engines have
been converted to 12-volt, negative ground, with an alternator replacing
the generator. This conversion improves cold-starting performance and
allows the use of modern halogen lighting. Starter System: Electric
starter with a foot-operated or push-button activation.
Dry Engine Weight (complete with manifolds, no flywheel): 295 kg (650
lb).
Overall Length (front of pulley to flywheel face): 762 mm (30.0 in).
Overall Width (including manifolds): 508 mm (20.0 in).
Overall Height (oil pan to valve cover top): 711 mm (28.0 in).
Valve Lash (Intake, cold): 0.36 mm (0.014 in).
Valve Lash (Exhaust, cold): 0.41 mm (0.016 in).
Spark Plug Type (original): Champion W-18 or equivalent.
Spark Plug Gap: 0.64 mm (0.025 in).
Ignition Point Gap: 0.38 mm (0.015 in).
Ignition Timing (static): TDC (top dead center) on number 1 cylinder.
Ignition Timing (dynamic at 1,650 rpm): 5° BTDC.
Engine Oil Change Interval: 100 operating hours.
Oil Filter Change Interval: 200 operating hours.
Coolant Change Interval: Annually or 500 operating hours.
Air Cleaner Service Interval (oil-bath): Clean cup and replace oil every
50 hours.
Valve Lash Inspection Interval: 500 operating hours.
Cylinder Head Bolts: 108-122 Nm (80-90 lb-ft).
Connecting Rod Cap Nuts: 61-68 Nm (45-50 lb-ft).
Main Bearing Cap Bolts: 102-115 Nm (75-85 lb-ft).
Flywheel Bolts: 122-136 Nm (90-100 lb-ft).
Crankshaft Pulley Bolt: 136-150 Nm (100-110 lb-ft).
Rocker Arm Shaft Bracket Bolts: 34-41 Nm (25-30 lb-ft).
Intake and Exhaust Manifold Nuts: 27-34 Nm (20-25 lb-ft).
Valve Cover Bolts: 7-10 Nm (5-7 lb-ft).
Oil Pan Bolts: 14-20 Nm (10-15 lb-ft).
Distributor Clamp Bolt: 14-20 Nm (10-15 lb-ft).
Spark Plugs: 27-34 Nm (20-25 lb-ft).
Oil Drain Plug: 27-34 Nm (20-25 lb-ft).
1939-1954 Farmall H (Row-Crop Tractor): The primary application for the
C152 engine. The Farmall H was a versatile row-crop tractor used for
plowing, cultivating, planting, and belt work. The engine was mounted
longitudinally, directly bolted to the transmission. This application
remains the most common source of the C-152 engine today.
1940-1954 International W-4 (Standard Tractor): The W-4 was the
standard-tread (wheatland) version of the Farmall H, with a lower ground
clearance and wider front axle. The C152 produced identical power
ratings in this configuration.
1940-1954 International I-4 (Industrial Tractor): The I-4 used the C152
engine for industrial applications including warehouse towing, yard
work, and light construction. These tractors featured heavier-duty front
axles and a yellow paint scheme.
International Power Unit (Stationary Application): The C152 was sold as
a stationary power unit (designated U-2 or similar) for driving pumps,
generators, compressors, and other industrial equipment. These units
included a radiator, governor, and belt pulley but lacked a
transmission.
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