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International D188 Engine

The International Harvester D188 is a 3.1-liter (187.5 cubic inches), 4-cylinder, inline, liquid-cooled diesel engine primarily utilized in agricultural and industrial machinery, including the Farmall 504, International 2504, and 3514 loader tractors. Engineered as a structural power unit, the engine block features a cast-in bell housing and front mounting points to eliminate the need for traditional chassis frame rails. Design architecture is heavily standardized, representing exactly two-thirds of the six-cylinder D-282 engine, sharing an identical cylinder bore and utilizing dry type cylinder sleeves. It is widely recognized by service technicians as a highly reliable, heavy-duty engine built for high-torque longevity.

The engine uses an overhead valve (OHV) configuration. The valves are positioned vertically in the cylinder head, with two valves per cylinder (one intake, one exhaust). The valve train is mechanically operated by solid pushrods and rocker arm assemblies driven by a camshaft located in the engine block. The camshaft itself is driven by the timing gear train from the front of the crankshaft. Cylinder Bore: 3.687 in (94 mm). Piston Stroke: 4.390 inches (112 mm). Compression Ratio: 18.7:1 static compression.

Fuel System: This engine features an indirect injection (IDI) diesel fuel system utilizing glow plugs as a cold-starting aid. Fuel is delivered via a mechanical, rotary distributor-type injection pump (commonly a Roosa Master unit) timed directly to the engine gear train. The injection pump forces high-pressure fuel to mechanical pintle-type fuel injectors, which atomize the fuel directly into pre-combustion chambers (pre-chambers) cast within the cylinder head. The system incorporates a multi-stage filtration process, including a primary fuel filter/water separator assembly and a secondary fine-particle fuel filter.

Lubrication System: The lubrication system is a full pressure, force-feed configuration. A gear-type oil pump driven directly by the crankshaft draws oil from the oil pan through a screened intake tube. Oil is routed under pressure through a full-flow oil filter element to the main oil galleries, supplying the crankshaft main bearings, connecting rod journals, and camshaft bearings. An oil pressure relief valve regulates system pressure.

Cooling System: Engine temperature is maintained by a pressurized, closed liquid-cooling system. A belt-driven centrifugal water pump forces coolant through the engine block water jackets and cylinder head passages. A pellet-type thermostat regulates temperature, closing to redirect coolant through a bypass circuit during warm-up and opening to allow full flow through the radiator once operational temperature is reached.

General Technical Data

Engine Specifications

Engine Model ............... International Harvester D188
Engine Type ............... 4-cycle inline 4-cylinder indirect injection liquid-cooled diesel
Number of Cylinders ............... 4
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 3.6875 (93.66)
Engine Stroke, in (mm) ............... 4.390 (111.51)
Displacement, cu.in (L) ............... 187.5 (3.1)
Rated Engine Power, hp (kW) ............... 46-55 (34.3-41.0)
Rated Engine Speed, rpm ............... 2200
Maximum Low Idle Speed, rpm ............... 700-750
Maximum High Idle Speed, rpm ............... 2425-2475
Aspiration Type ............... Naturally Aspirated
Compression Ratio ............... 18.7:1
Firing Order ............... 1-3-4-2
Crankshaft Design ............... Forged steel counterbalanced hardened journals
Camshaft Drive Method ............... Helical gear train drive system
Valves Per Cylinder ............... 2 overhead valves per cylinder
Cylinder Block Type ............... Cast iron structural block
Cylinder Head Type ............... Cast iron single piece
Combustion Chamber ............... Pre-combustion chamber with glow plugs
Lubrication System ............... Full-pressure circulation
Oil Pump Type ............... Gear-driven internal assembly
Oil Filter Type ............... Full-flow spin-on cartridge replaceable element
Cooling System Type ............... Forced circulation liquid-cooled
Water Pump Type ............... Belt-driven centrifugal impeller
Air Cleaner Type ............... Heavy duty oil bath or dry dual element option
Starting System ............... Electric starter motor
Electrical System, V ............... 12
Alternator Output, A ............... 35

Fuel System

Injection Pump Model ............... Roosa Master DBGFC431 or similar series
Injection Pump Type ............... Rotary distributor type single plunger mechanical
Injection Pump Drive ............... Gear driven from the main timing gear train
Injection Pump Timing, deg BTDC ............... 4.0-6.0
Fuel Injection Pressure, psi (bar) ............... 1800-2100 (124.1-144.8)
Fuel Transfer Pump Type ............... Mechanical vane type integral to rotary pump
Fuel Transfer Pump Pressure, psi (bar) ............... 12.0-45.0 (0.83-3.10)
Fuel Injector Type ............... Multi-orifice nozzle
Nozzle Holder Assembly ............... External clamp down
Primary Fuel Filter Type ............... Replaceable paper element spin-on water separator
Secondary Fuel Filter Type ............... Fine micron secondary final stage canister
Fuel Tank Capacity, gal (L) ............... 18.6 (70.4)
Governor Type ............... Mechanical centrifugal type integrated with pump
Injection Advance Mechanism ............... Hydraulic automatic load sensing
Fuel System Bleed Method ............... Manual vent screw purging via primary filter base
Fuel Feed Pipe Diameter, in (mm) ............... 0.3125 (7.93)
High Pressure Line Material ............... Thick-walled seamless steel structural tubing

Dimensions and Weight

Overall Length, in (mm) ............... 34.5 (875)
Overall Width, in (mm) ............... 22.8 (580)
Overall Height, in (mm) ............... 35.2 (895)
Dry Weight, lbs (kg) ............... 685 (310)
Wet Weight, lbs (kg) ............... 735 (333)

Maintenance Data

Service Information

Compression Pressure, Minimum Limit, psi (bar) ............... 300 (20.68)
Oil Pressure at Rated Speed, psi (bar) ............... 30.0 (2.06)
Oil Pressure at Idle Speed, psi (bar) ............... 10.0 (0.69)
Thermostat Opening Temperature, F (C) ............... 180 (82.2)
Thermostat Full Open Temperature, F (C) ............... 202 (94.4)
Radiator Cap Relief Pressure, psi (bar) ............... 7.0 (0.48)
Fan Belt Tension Deflection, in (mm) ............... 0.5 (12.7)
Intake Valve Clearance, Cold, in (mm) ............... 0.014 (0.35)
Exhaust Valve Clearance, Cold, in (mm) ............... 0.014 (0.35)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30W, 10W-30
API Service Classifications ......................... CC or CD
Engine Oil Capacity, qt (L) ............... 5.0 (4.7)
Engine Oil Capacity with Filter, qt (L) ............... 5.5 (5.2)
Air Cleaner Oil Bath Capacity, pt (L) ............... 1.5 (0.71)
Cooling System Liquid Capacity, qt (L) ............... 16.0 (15.1)

Service Intervals

Change oil and filter ............... Every 100 hours
Inspect air cleaner ............... Every 50 hours
Service air cleaner ............... Every 500 hours
Replace fuel filter ............... Every 250 hours
Valve clearance adjustment ............... Every 400 hours
Fuel system inspection ............... Every 1000 hours
Change coolant ............... Every 1000 hours
Compression test ............... Every 1000 hours
Belt inspection ............... Every service cycle

Service Specifications

Cylinder Bore Diameter, Std, in (mm) ............... 3.6875-3.6890 (93.663-93.701)
Cylinder Bore Diameter, Wear Limit, in (mm) ............... 3.6940 (93.828)
Cylinder Liner Flange Outside Diameter, in (mm) ............... 4.165 (105.79)
Crankshaft Main Journal Diameter, in (mm) ............... 2.998-2.999 (76.149-76.175)
Crankshaft Main Journal Diameter, Wear Limit, in (mm) ............... 2.995 (76.073)
Crankshaft Main Bearing Oil Clearance, in (mm) ............... 0.0020-0.0038 (0.051-0.097)
Crankshaft End Play, in (mm) ............... 0.003-0.009 (0.076-0.229)
Con Rod Journal Diameter, in (mm) ............... 2.548-2.549 (64.719-64.745)
Con Rod Journal Diameter, Wear Limit, in (mm) ............... 2.544 (64.618)
Con Rod Bearing Oil Clearance, in (mm) ............... 0.0018-0.0035 (0.046-0.089)
Con Rod Side End Play, in (mm) ............... 0.006-0.011 (0.152-0.279)
Piston Skirt Clearance to Bore Wall, in (mm) ............... 0.0035-0.0045 (0.089-0.114)
Piston Pin Diameter, in (mm) ............... 1.2500-1.2504 (31.750-31.760)
Piston Pin Clearance in Con Rod Bushing, in (mm) ............... 0.0005-0.0011 (0.013-0.028)
Piston Pin Clearance in Piston Boss, in (mm) ............... 0.0002-0.0006 (0.005-0.015)
Top Ring Side Clearance, in (mm) ............... 0.0025-0.0040 (0.064-0.102)
Second Ring Side Clearance, in (mm) ............... 0.0020-0.0035 (0.051-0.089)
Oil Ring Side Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Top Ring End Gap, in (mm) ............... 0.011-0.021 (0.279-0.533)
Second Ring End Gap, in (mm) ............... 0.009-0.019 (0.229-0.483)
Oil Ring End Gap, in (mm) ............... 0.010-0.020 (0.254-0.508)
Cylinder Head Distortion Maximum, in (mm) ............... 0.003 (0.076)
Cylinder Block Deck Flatness Maximum, in (mm) ............... 0.004 (0.102)
Intake Valve Stem Diameter, in (mm) ............... 0.3715-0.3725 (9.436-9.462)
Exhaust Valve Stem Diameter, in (mm) ............... 0.3705-0.3715 (9.411-9.436)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0015-0.0035 (0.038-0.089)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0025-0.0045 (0.064-0.114)
Valve Guide Inside Diameter, in (mm) ............... 0.374-0.375 (9.500-9.525)
Valve Seat Angle, deg ............... 45
Valve Face Angle, deg ............... 45
Valve Spring Free Length, in (mm) ............... 2.125 (53.98)
Camshaft Journal Diameter, Number 1, in (mm) ............... 2.122-2.123 (53.899-53.924)
Camshaft Journal Diameter, Number 2, in (mm) ............... 2.091-2.092 (53.111-53.137)
Camshaft Journal Diameter, Number 3, in (mm) ............... 2.060-2.061 (52.324-52.349)
Camshaft Journal Diameter, Number 4, in (mm) ............... 1.998-1.999 (50.749-50.775)
Camshaft Bearing Clearance, in (mm) ............... 0.0020-0.0045 (0.051-0.114)
Camshaft End Play, in (mm) ............... 0.003-0.007 (0.076-0.178)
Cam Lobe Lift, Intake, in (mm) ............... 0.312 (7.92)
Cam Lobe Lift, , in (mm) ............... 0.312 (7.92)
Rocker Arm Shaft Outside Diameter, in (mm) ............... 0.748-0.749 (19.00-19.02)
Rocker Arm Bushing Inside Diameter, in (mm) ............... 0.750-0.751 (19.05-19.08)
Rocker Arm Bushing Oil Clearance, in (mm) ............... 0.001-0.003 (0.025-0.076)
Tappet Body Valve Lifter Outside Diameter, in (mm) ............... 0.998-0.999 (25.35-25.37)
Tappet Clearance in Cylinder Block Bore, in (mm) ............... 0.0010-0.0025 (0.025-0.064)

Tightening Torques

Cylinder Head Bolts (Stage 1), lb-ft (Nm) ............... 45.0 (61.0)
Cylinder Head Bolts (Stage 2), lb-ft (Nm) ............... 80.0 (108.5)
Cylinder Head Bolts (Stage 3), lb-ft (Nm) ............... 115.0 (155.9)
Connecting Rod Bolts, lb-ft (Nm) ............... 50.0 (67.8)
Main Bearing Cap Bolts, lb-ft (Nm) ............... 95.0 (128.8)
Flywheel Mounting Screws, lb-ft (Nm) ............... 75.0 (101.7)
Crankshaft Vibration Damper Hub Screw, lb-ft (Nm) ............... 140.0 (189.8)
Camshaft Thrust Plate Bolts, lb-ft (Nm) ............... 22.0 (29.8)
Camshaft Timing Gear Attachment Bolts, lb-ft (Nm) ............... 65.0 (88.1)
Rocker Arm Shaft Bracket Screws, lb-ft (Nm) ............... 28.0 (38.0)
Cylinder Head Rocker Cover Screws, lb-ft (Nm) ............... 10.0 (13.6)
Timing Gear Housing Plate to Block Screws, lb-ft (Nm) ............... 25.0 (33.9)
Timing Gear Cover Outer Face Screws, lb-ft (Nm) ............... 18.0 (24.4)
Oil Pan Sump Drain Plug, lb-ft (Nm) ............... 45.0 (61.0)
Intake Manifold Flange Holding Stud Nuts, lb-ft (Nm) ............... 25.0 (33.9)
Exhaust Manifold Flange High Temp Nuts, lb-ft (Nm) ............... 30.0 (40.7)
Fuel Injection Pump Drive Hub Nuts, lb-ft (Nm) ............... 45.0 (61.0)
Fuel Injection Pump Mounting Locking Nuts, lb-ft (Nm) ............... 25.0 (33.9)
Fuel Injector Clamp Down Bracket Screws, lb-ft (Nm) ............... 20.0 (27.1)
Fuel High Pressure Fuel Delivery Tubing Nuts, lb-ft (Nm) ............... 22.0 (29.8)
Glow Plug Assembly Threaded Hex Mounts, lb-ft (Nm) ............... 15.0 (20.3)
Glow Plug Electrical Wiring Terminal Nuts, lb-ft (Nm) ............... 2.0 (2.7)
Water Pump Assembly Core Bracket Nuts, lb-ft (Nm) ............... 25.0 (33.9)
Water Pump Fan Drive Pulley Hub Screws, lb-ft (Nm) ............... 15.0 (20.3)
Thermostat Housing Assembly Cover Studs, lb-ft (Nm) ............... 18.0 (24.4)
Oil Pump Internal Housing Cover Assembly, lb-ft (Nm) ............... 12.0 (16.3)
Oil Pump Pressure Relief Valve Plugs, lb-ft (Nm) ............... 35.0 (47.5)
Oil Filter Core Adaptation Base Fasteners, lb-ft (Nm) ............... 25.0 (33.9)
Starter Motor Structural Flange Mounting Main Bolts, lb-ft (Nm) ............... 45.0 (61.0)
Generator Alternator Pivoting Tension Bracket, lb-ft (Nm) ............... 30.0 (40.7)
Flywheel Housing Core to Block Interface, lb-ft (Nm) ............... 55.0 (74.6)

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