1937–1940 International Harvester F12, F14, O12, O14, W12, W14, F20, F30, 1020, W30, W40 Tractor Shop Manual

This shop manual covers 1937–1940 International Harvester F12, F14, O12, O14, W12, W14, F20, F30, 1020, W30, and W40 tractors, with model-specific repair procedures, component illustrations, and service tables.

• Engine repair: Engine removal, cylinder-head service, valve timing, camshaft bearings, wet cylinder sleeves, pistons, connecting rods, crankshafts, and flywheel installation checks.

• Fuel and ignition: IH carburetor overhaul, governor adjustment and synchronization, F4/F6 magneto timing, and impulse-coupling illustrations.

• Clutches and transmissions: Clutch removal and adjustment, over-center clutch inspection, transmission shaft removal, shifter mechanisms, and model-specific overhaul access.

• Final drive and PTO: Differential and bull-gear removal, bevel-gear mesh adjustment, axle bearings, power take-off shafts, and belt-pulley assemblies.

• Steering and brakes: Steering-knuckle and bolster service, worm-gear adjustments, brake relining, and hand-lever or pedal-linkage adjustment.

• Cooling system: Fan assemblies, belt adjustment, thermostat control, and water-pump removal, repacking, and overhaul.

• Power-lift reference: F12/F14 hydraulic and F30 mechanical power-lift sectional views; detailed power-lift service procedures are not included.

This manual is suited to experienced tractor mechanics familiar with bearing fits, shim adjustments, and the lifting equipment needed for engine and drivetrain removal.

Engine Components and Assembly Checks

The engine sections distinguish the W40’s two-piece cylinder head from the other designs and explain the different piston-removal and crankshaft-bearing arrangements. Tables organize piston-ring gaps, bearing clearances, valve tappet settings, and camshaft data by model group.

The W40 connecting-rod notes flag the one-sided shim arrangement, where incorrect placement can compromise bearing fit. For the pressed-on flywheels used on F20, F30, 1020, and W30 tractors, the manual covers tapered-dowel alignment, reaming, and dial-indicator runout checks.

Engine side sectional views include the 12/14-series arrangement and the W40 layout, showing the relationship between the valve train, cylinder sleeves, and lubrication passages.

Carburetors, Governors, and Magneto Timing

Fuel-system coverage: Overhaul instructions cover the IH A10 downdraft carburetor and the 1020’s IH R sidedraft carburetor. The A10 cross-sections and the R carburetor’s idle-system view accompany inspection and adjustment information. The series 12/14 fuel pump is identified, without a dedicated pump-overhaul procedure.

Zenith carburetor models are identified, but their adjustment, overhaul, and calibration procedures are referred to a separate Standard Units section that is not included in this PDF.

Governor and ignition work: Governor sections cover linkage synchronization, governed-speed adjustment, spring data, and internal inspection. F4 and F6 magneto timing instructions include distributor-position and impulse-coupling illustrations.

Magneto overhaul and generator, regulator, and starter testing also refer to the omitted Standard Units material. This file does not include electrical wiring diagrams.

Cooling and Lubrication Service

The cooling coverage distinguishes thermosiphon systems from the pump-circulated arrangements used on F30, W30, and W40 tractors. Fan assemblies, radiator construction, and the adjustable bypass thermostats on F30/W30 models are described alongside water-pump service.

The pump-overhaul notes explain how an incorrect spacer can preload the fan-hub bearings and cause binding. Oil-pump sections cover the different assemblies, pressure-relief components, and relief-spring checks.

Clutches, Transmission Access, and Final Drive

Clutch work: Removal and adjustment instructions cover spring-loaded and over-center designs, including clutch brakes. Over-center clutch inspection is described; spring-loaded clutch overhaul refers to the separate Standard Units material.

Repair planning: F12/F14 transmission work can be performed without separating the transmission from the main frame, while main-drive bevel-pinion removal on O12/O14/W12/W14 tractors requires engine removal. These access distinctions help establish the lifting and teardown needed before work begins.

Transmission top and side sectional views support shaft and bearing work. Differential and bull-gear procedures lead into bevel-gear adjustment, with tooth-contact charts explaining the patterns produced by marking compound. PTO and belt-pulley sections distinguish their bearing, sealing, and drive arrangements.

Steering, Brakes, and Power-Lift Limits

Steering assembly drawings accompany knuckle, bolster, worm-shaft, and gear-mesh work. Brake sections distinguish internal expanding shoes from external bands and describe the different hand-lever, pedal, and steering-linked arrangements.

F12/F14 hydraulic power lifts and F30 single- and double-lift mechanisms are shown in sectional views. The power-lift section explicitly provides illustrations rather than detailed service instructions.

Follow appropriate shop safety practices for supporting the tractor and lifting heavy assemblies; consult a qualified tractor technician before major powertrain work if needed.

Examples of Oil-Pressure and Bevel-Gear Specifications

The pressure-lubricated 12/14-series engines and W40 have a specified system oil pressure of 30–40 psi. That specification does not apply to the splash-lubricated F20, F30, 1020, and W30 engines.

Main-drive bevel-gear backlash is listed as 0.008–0.010 in. for F20/F30 and 0.010–0.012 in. for 1020/W30/W40. The adjustment section relates these clearances to tooth-contact patterns and the respective shim or adjusting-nut arrangements.

PDF Search, Index, and Included Pages

Text search and navigation: The existing OCR text layer is only partially searchable, with gaps in tables and engine sections, including PDF pp. 11–12. There are no embedded PDF bookmarks. The printed index references paragraph numbers.

Supplied as one printable, English-language 50-page PDF. This total includes 44 pages of identification, index, service data, and repair content, plus one cover page, two notes pages, one blank back-cover page, and two additional nontechnical pages.