John Deere 316, 318 & 420 Lawn and Garden Tractors Service Manual (P/N TM1590)

• Functions as the complete OEM-authorized reference for 1981–1993 John Deere 316, 318, and 420 lawn and garden tractors, mapping out specialized hydrostatic transmission, axle, and differential configurations.
• Official TM1590 publication (published May 17, 1995) featuring 47 exploded-view diagrams and 35 technical specification tables to support daily shop repair and diagnostic workflows.
• 660-page PDF covers every chapter, appendix, chassis detail, and electrical subsystem.
• Details step-by-step procedures for mower gear case rebuilds, mower blade spindle service, drive shaft removals, shoe and drum brake adjustments, manual steering gearbox overhauls, power steering valve testing, front axle maintenance, and dealer fabricated tools.
• Includes essential diagnostic references like wiring diagrams, hydraulic schematics, electrical component location views, metric series torque charts, inch series torque charts, set screw torque charts, and troubleshooting guides.

Document Structure and Workshop Utility

This service publication provides granular technical data for the internal mechanical systems of these classic machines. Organized strictly by functional area, it accelerates the diagnostic process by detailing precise test port locations and baseline pressure readings, preventing unnecessary parts replacement. You start with standard safety procedures and general machine specifications. Working on pressurized hydraulics and heavy tractor powertrains carries inherent physical risks. Always review the integrated safety protocols before securing machinery on jack stands or turning a wrench.

From there, dedicated sections break down front PTO clutch maintenance, power train assemblies, steering calibration, and hydraulic control valve operation. To avoid expensive dealership labor, the manual delivers step-by-step instructions for rebuilding the 50-inch, 60-inch, and 260 rotary mower gear cases, overhauling the manual and hydrostatic power steering systems, and safely bleeding the entire hydraulic circuit. The factory layout allows systematic navigation through complex electrical schematics and diagnostic tests for the infinite-speed hydrostatic drive systems.

Specifications and Technical Preview

While engine overhaul specifications cross-reference to CTM2, this manual houses all machine-level hydraulic and power train data. Need exact torque numbers? The charge pump mounting torque is listed at 70 N·m (52 lb-ft). Differential lock values are documented at 53 N·m (39 lb-ft), and front axle fasteners require 140 N·m (103 lb-ft).

Beyond torque ratings, the publication details critical fluid and pressure parameters. It specifies hydraulic system pressure settings at 5861–6722 kPa (850–975 psi) for the implement relief valve. Transmission capacity is officially rated at 7.1 L (15 U.S. pt) for the 318 and 420 models. Advanced diagnostics are also covered. The steering system leakage test calls out a specific 6.8 N·m (60 lb-in.) applied to the steering wheel nut at slow idle. Relying on this official documentation provides the authoritative specifications required for any major component repair.