M939 M939A1 M939A2 5-Ton 6×6 Truck Direct & General Support Maintenance Manual – TM 9-2320-272-34-1 Volume 1

Description

M939 M939A1 M939A2 5-Ton 6×6 Truck Direct & General Support Maintenance Manual – TM 9-2320-272-34-1 Volume 1

This U.S. Army technical manual covers Direct Support and General Support maintenance for the 5-ton, 6×6, M939, M939A1, and M939A2 series diesel trucks. Published as TM 9-2320-272-34-1 (Air Force TO 36A12-1C-452-1), Volume 1 of 2, and updated through Change 2 in 1991, it contains Chapters 1 through 7 spanning engine maintenance, fuel system repair, cooling system service, electrical system diagnostics, and automatic transmission overhaul. Whether you maintain, repair, or restore an M923 cargo truck, M929 dump truck, M931 tractor, M934 expansible van, or M936 medium wrecker, this manual provides the step-by-step procedures, specifications, and troubleshooting guidance used at the direct and general support maintenance levels.

File Details

• Manual Type: Direct Support and General Support Maintenance Technical Manual
• Document Number: TM 9-2320-272-34-1 / TO 36A12-1C-452-1
• Date: 10 June 1986 (Change 2, 1991)
• Volume: 1 of 2 (Chapters 1-7)
• Language: English
• Page Count: 1,037
• Format: PDF

Chapters Covered

• Chapter 1 – Introduction: Scope, general information, equipment description and data, maintenance forms and records, destruction of Army equipment procedures
• Chapter 2 – Service and Troubleshooting Instructions: Repair parts, special tools, TMDE and support equipment; general service instructions for cleaning, inspection, repair, and assembly; comprehensive troubleshooting guides for engine, fuel system, cooling system, transmission, transfer case, air compressor, steering, front/rear axles, dump body, medium wrecker crane, and power takeoff
• Chapter 3 – Engine Maintenance: Cummins NHC-250 diesel engine description and data; in-vehicle maintenance including access cover, water header plates, exhaust manifold, oil cooler, vibration damper, crankshaft flange, accessory drive, intake manifold, fuel supply and return tubes, lift eyes, rocker lever housings, valve crossheads, fuel crossover connectors, cylinder heads, cam follower housing, and oil pan; engine replacement procedures; complete engine repair including mounting on repair stand, water header plates removal, water manifold removal, fan and fan drive clutch removal, water pump removal, vibration damper removal, crankshaft flange removal, accessory drive pulley removal, fuel pump removal, air compressor removal, oil pump return hose/pickup hose/sump tube removal, oil filter removal, front gearcase cover maintenance, accessory drive removal, oil pump maintenance, intake manifold removal, fuel supply/return tube removal, rocker lever housing covers removal, rocker lever housings and push tubes removal, valve crossheads removal, fuel crossover connectors removal, injectors removal, cylinder head maintenance, refacing intake and exhaust valves, valve seat insert replacement, grinding valve seats, injector sleeve replacement, cam follower housing removal, flywheel ring gear removal, flywheel housing removal, crankshaft rear cover seal and plate removal, engine oil pan removal, camshaft and gear maintenance, connecting rod and piston maintenance, crankshaft and main bearings removal, cylinder liners and cylinder block maintenance; engine reassembly; engine valve and injector adjustments
• Chapter 4 – Fuel System Maintenance: Fuel pump description and data (standard and variable speed PT, Type G, AFC plugged); fuel injector description (non-top stop and top stop); fuel pump replacement; fuel pump shutoff valve replacement (standard and M936); fuel pump mounting to holding fixture; pulsation damper maintenance; pressure gear pump removal; governor spring pack maintenance; fuel pump housing disassembly; throttle cover and shaft disassembly; governor weight removal; front drive cover disassembly; tachometer drive disassembly; fuel pump reassembly; fuel pump setup and calibration including throttle shaft cover removal, mounting pump to test stand, fuel pump run-in, testing pump seals for leaks, testing governor cutoff RPM, testing and adjusting throttle leakage, testing and adjusting idle speed, checking and adjusting throttle lever travel, testing and adjusting pump main pressure, testing and adjusting fuel pressure, testing and adjusting governor fuel pressure, checking and adjusting governor weight pressure, testing and adjusting idle speed (VS governor only), shutdown and removal from test stand; fuel injector maintenance; fuel injector overhaul instructions; injector leakage test; injector spray pattern test; injector test stand calibration; injector flow test
• Chapter 5 – Cooling System Maintenance: General description and data; radiator maintenance (disassembly, cleaning/inspection/repair, reassembly); water manifold maintenance; fan drive clutch maintenance including operation check; water pump maintenance; repair and replacement standards for water pump
• Chapter 6 – Electrical System Maintenance: Alternator description; starter motor and solenoid description; electrical system tabulated data; front lights cable assembly replacement; front wiring harness replacement; rear wiring harness replacement; alternator adjustment
• Chapter 7 – Automatic Transmission Maintenance: Allison MT654CR automatic transmission description and data; general transmission replacement task summary; transmission shift cable replacement; transmission selector shaft oil seal replacement; transmission mount bushing replacement; transmission output shaft oil seal replacement; transmission lubrication valve replacement; transmission 5th gear lock-in solenoid valve and bracket replacement; transmission replacement (from vehicle); transmission replacement (engine and transmission removed from vehicle); transmission disassembly including mounting to holding fixture, torque converter removal, oil pan removal, oil filter removal, modulated lockup valve removal, low trimmer valve removal, low shift valve removal, control valve removal, manual selector shaft removal, oil pump and front support removal, turbine shaft removal, fourth clutch removal, third clutch removal, center support removal, gear unit and main shaft removal, second clutch removal, first clutch removal, governor removal, rear cover and low planetary carrier removal, low clutch removal, adapter housing and first clutch piston removal, transmission housing repair; transmission reassembly; transmission tests and adjustments including oil pressure testing, modulator maintenance, and converter stall test

This manual is designed for direct support and general support maintenance personnel – the intermediate and depot-level mechanics who perform repairs beyond organizational-level troubleshooting. Every procedure includes detailed step-by-step instructions, exploded-view illustrations, torque specifications, wear limits, and inspection criteria. The engine chapter alone spans hundreds of pages covering complete disassembly, component inspection and measurement, and reassembly of the Cummins NHC-250 diesel. The transmission chapter provides the same depth for the Allison MT654CR automatic, including valve body service, clutch pack clearance measurement, and complete calibration procedures on a test stand.

Beyond engine and transmission work, the manual covers the fuel system in exhaustive detail – from pump removal and replacement through complete teardown, calibration, and injector testing. Cooling system maintenance covers the radiator, water manifold, fan drive clutch (with operation check), and water pump with complete repair and replacement standards. The electrical system section includes front and rear wiring harness replacement, front lights cable assembly, and alternator adjustment. The troubleshooting chapter provides symptom-based diagnostics for the entire vehicle, covering everything from engine cranks/fails to start to transmission shift problems to dump body hydraulic issues and medium wrecker crane malfunctions.

Models Covered

• M923, M923A1, M923A2 – Cargo Truck, Dropside, Without Winch
• M924, M924A1, M924A2 – Cargo Truck, Without Winch
• M925, M925A1, M925A2 – Cargo Truck, Dropside, With Winch
• M926, M926A1, M926A2 – Cargo Truck, With Winch
• M927, M927A1, M927A2 – Cargo Truck, XLWB, Without Winch
• M928, M928A1, M928A2 – Cargo Truck, XLWB, With Winch
• M929, M929A1, M929A2 – Dump Truck, Without Winch
• M930, M930A1, M930A2 – Dump Truck, With Winch
• M931, M931A1, M931A2 – Tractor Truck, Without Winch
• M932, M932A1, M932A2 – Tractor Truck, With Winch
• M934, M934A1, M934A2 – Expansible Van, Without Winch
• M935, M935A1, M935A2 – Expansible Van, With Winch (With Hydraulic Lift Gate)
• M936, M936A1, M936A2 – Medium Wrecker, With Winch

What This Manual Enables You to Do

With this M939 M939A1 M939A2 maintenance manual on hand, a qualified mechanic can perform complete direct support and general support maintenance on any M939 series 5-ton truck. That includes removing and replacing the engine, disassembling and rebuilding the Cummins NHC-250, servicing the Allison MT654CR automatic transmission at the component level, calibrating the fuel pump and injectors on a test stand, repairing the cooling system from radiator to water pump, troubleshooting electrical faults, and diagnosing drivability problems across the entire vehicle.

The procedures include the exact torque values, wear limits, and adjustment specifications required to bring components back to serviceable condition. The troubleshooting chapter alone can save hours of diagnostic guesswork by directing you through logical step-by-step tests to isolate the source of a problem – whether it’s low power, rough shifting, overheating, excessive oil consumption, or a crane that won’t swing.

If you own, operate, restore, or maintain an M939 series truck, having the correct procedures and specifications matters. These vehicles are built to military standards, and servicing them with generic repair advice risks costly damage. This M939 M939A1 M939A2 service manual gives you the factory-authorized procedures used by the Army’s own maintenance personnel.

Delivered as an instant PDF download after payment – no shipping, no waiting. Read it on any device, print the pages you need for the shop, and keep the full manual on hand for reference. Whether you’re doing a one-time repair or a full restoration, TM 9-2320-272-34-1 Volume 1 provides the technical foundation you need.